review.tizen.org Git - platform/kernel/linux-starfive.git/log

btrfs: avoid link error with CONFIG_NO_AUTO_INLINE

Note: this patch fixes a problem in a feature outside of btrfs ("kernel
hacking: add a config option to disable compiler auto-inlining") and is
applied ahead of time due to cross-subsystem dependencies.

On 32-bit ARM with gcc-8, I see a link error with the addition of the
CONFIG_NO_AUTO_INLINE option:

fs/btrfs/super.o: In function `btrfs_statfs':
super.c:(.text+0x67b8): undefined reference to `__aeabi_uldivmod'
super.c:(.text+0x67fc): undefined reference to `__aeabi_uldivmod'
super.c:(.text+0x6858): undefined reference to `__aeabi_uldivmod'
super.c:(.text+0x6920): undefined reference to `__aeabi_uldivmod'
super.c:(.text+0x693c): undefined reference to `__aeabi_uldivmod'
fs/btrfs/super.o:super.c:(.text+0x6958): more undefined references to `__aeabi_uldivmod' follow

So far this is the only file that shows the behavior, so I'd propose
to just work around it by marking the functions as 'static inline'
that normally get inlined here.

The reference to __aeabi_uldivmod comes from a div_u64() which has an
optimization for a constant division that uses a straight '/' operator
when the result should be known to the compiler. My interpretation is
that as we turn off inlining, gcc still expects the result to be constant
but fails to use that constant value.

Link: https://lkml.kernel.org/r/20181103153941.1881966-1-arnd@arndb.de
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[ add the note ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: tree-checker: Fix misleading group system information

block_group_err shows the group system as a decimal value with a '0x'
prefix, which is somewhat misleading.

Fix it to print hexadecimal, as was intended.

Fixes: fce466eab7ac6 ("btrfs: tree-checker: Verify block_group_item")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix missing data checksums after a ranged fsync (msync)

Recently we got a massive simplification for fsync, where for the fast
path we no longer log new extents while their respective ordered extents
are still running.

However that simplification introduced a subtle regression for the case
where we use a ranged fsync (msync). Consider the following example:

               CPU 0                                    CPU 1

                                            mmap write to range [2Mb, 4Mb[
  mmap write to range [512Kb, 1Mb[
  msync range [512K, 1Mb[
    --> triggers fast fsync
        (BTRFS_INODE_NEEDS_FULL_SYNC
         not set)
    --> creates extent map A for this
        range and adds it to list of
        modified extents
    --> starts ordered extent A for
        this range
    --> waits for it to complete

                                            writeback triggered for range
                                            [2Mb, 4Mb[
                                              --> create extent map B and
                                                  adds it to the list of
                                                  modified extents
                                              --> creates ordered extent B

    --> start looking for and logging
        modified extents
    --> logs extent maps A and B
    --> finds checksums for extent A
        in the csum tree, but not for
        extent B
  fsync (msync) finishes

                                              --> ordered extent B
                                                  finishes and its
                                                  checksums are added
                                                  to the csum tree

                                <power cut>

After replaying the log, we have the extent covering the range [2Mb, 4Mb[
but do not have the data checksum items covering that file range.

This happens because at the very beginning of an fsync (btrfs_sync_file())
we start and wait for IO in the given range [512Kb, 1Mb[ and therefore
wait for any ordered extents in that range to complete before we start
logging the extents. However if right before we start logging the extent
in our range [512Kb, 1Mb[, writeback is started for any other dirty range,
such as the range [2Mb, 4Mb[ due to memory pressure or a concurrent fsync
or msync (btrfs_sync_file() starts writeback before acquiring the inode's
lock), an ordered extent is created for that other range and a new extent
map is created to represent that range and added to the inode's list of
modified extents.

That means that we will see that other extent in that list when collecting
extents for logging (done at btrfs_log_changed_extents()) and log the
extent before the respective ordered extent finishes - namely before the
checksum items are added to the checksums tree, which is where
log_extent_csums() looks for the checksums, therefore making us log an
extent without logging its checksums. Before that massive simplification
of fsync, this wasn't a problem because besides looking for checkums in
the checksums tree, we also looked for them in any ordered extent still
running.

The consequence of data checksums missing for a file range is that users
attempting to read the affected file range will get -EIO errors and dmesg
reports the following:

[10188.358136] BTRFS info (device sdc): no csum found for inode 297 start 57344
[10188.359278] BTRFS warning (device sdc): csum failed root 5 ino 297 off 57344 csum 0x98f94189 expected csum 0x00000000 mirror 1

So fix this by skipping extents outside of our logging range at
btrfs_log_changed_extents() and leaving them on the list of modified
extents so that any subsequent ranged fsync may collect them if needed.
Also, if we find a hole extent outside of the range still log it, just
to prevent having gaps between extent items after replaying the log,
otherwise fsck will complain when we are not using the NO_HOLES feature
(fstest btrfs/056 triggers such case).

Fixes: e7175a692765 ("btrfs: remove the wait ordered logic in the log_one_extent path")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix pinned underflow after transaction aborted

When running generic/475, we may get the following warning in dmesg:

[ 6902.102154] WARNING: CPU: 3 PID: 18013 at fs/btrfs/extent-tree.c:9776 btrfs_free_block_groups+0x2af/0x3b0 [btrfs]
[ 6902.109160] CPU: 3 PID: 18013 Comm: umount Tainted: G        W  O      4.19.0-rc8+ #8
[ 6902.110971] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
[ 6902.112857] RIP: 0010:btrfs_free_block_groups+0x2af/0x3b0 [btrfs]
[ 6902.118921] RSP: 0018:ffffc9000459bdb0 EFLAGS: 00010286
[ 6902.120315] RAX: ffff880175050bb0 RBX: ffff8801124a8000 RCX: 0000000000170007
[ 6902.121969] RDX: 0000000000000002 RSI: 0000000000170007 RDI: ffffffff8125fb74
[ 6902.123716] RBP: ffff880175055d10 R08: 0000000000000000 R09: 0000000000000000
[ 6902.125417] R10: 0000000000000000 R11: 0000000000000000 R12: ffff880175055d88
[ 6902.127129] R13: ffff880175050bb0 R14: 0000000000000000 R15: dead000000000100
[ 6902.129060] FS:  00007f4507223780(0000) GS:ffff88017ba00000(0000) knlGS:0000000000000000
[ 6902.130996] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6902.132558] CR2: 00005623599cac78 CR3: 000000014b700001 CR4: 00000000003606e0
[ 6902.134270] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 6902.135981] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 6902.137836] Call Trace:
[ 6902.138939]  close_ctree+0x171/0x330 [btrfs]
[ 6902.140181]  ? kthread_stop+0x146/0x1f0
[ 6902.141277]  generic_shutdown_super+0x6c/0x100
[ 6902.142517]  kill_anon_super+0x14/0x30
[ 6902.143554]  btrfs_kill_super+0x13/0x100 [btrfs]
[ 6902.144790]  deactivate_locked_super+0x2f/0x70
[ 6902.146014]  cleanup_mnt+0x3b/0x70
[ 6902.147020]  task_work_run+0x9e/0xd0
[ 6902.148036]  do_syscall_64+0x470/0x600
[ 6902.149142]  ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 6902.150375]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 6902.151640] RIP: 0033:0x7f45077a6a7b
[ 6902.157324] RSP: 002b:00007ffd589f3e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
[ 6902.159187] RAX: 0000000000000000 RBX: 000055e8eec732b0 RCX: 00007f45077a6a7b
[ 6902.160834] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 000055e8eec73490
[ 6902.162526] RBP: 0000000000000000 R08: 000055e8eec734b0 R09: 00007ffd589f26c0
[ 6902.164141] R10: 0000000000000000 R11: 0000000000000246 R12: 000055e8eec73490
[ 6902.165815] R13: 00007f4507ac61a4 R14: 0000000000000000 R15: 00007ffd589f40d8
[ 6902.167553] irq event stamp: 0
[ 6902.168998] hardirqs last  enabled at (0): [<0000000000000000>]           (null)
[ 6902.170731] hardirqs last disabled at (0): [<ffffffff810cd810>] copy_process.part.55+0x3b0/0x1f00
[ 6902.172773] softirqs last  enabled at (0): [<ffffffff810cd810>] copy_process.part.55+0x3b0/0x1f00
[ 6902.174671] softirqs last disabled at (0): [<0000000000000000>]           (null)
[ 6902.176407] ---[ end trace 463138c2986b275c ]---
[ 6902.177636] BTRFS info (device dm-3): space_info 4 has 273465344 free, is not full
[ 6902.179453] BTRFS info (device dm-3): space_info total=276824064, used=4685824, pinned=18446744073708158976, reserved=0, may_use=0, readonly=65536

In the above line there's "pinned=18446744073708158976" which is an
unsigned u64 value of -1392640, an obvious underflow.

When transaction_kthread is running cleanup_transaction(), another
fsstress is running btrfs_commit_transaction(). The
btrfs_finish_extent_commit() may get the same range as
btrfs_destroy_pinned_extent() got, which causes the pinned underflow.

Fixes: d4b450cd4b33 ("Btrfs: fix race between transaction commit and empty block group removal")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix cur_offset in the error case for nocow

When the cow_file_range fails, the related resources are unlocked
according to the range [start..end), so the unlock cannot be repeated in
run_delalloc_nocow.

In some cases (e.g. cur_offset <= end && cow_start != -1), cur_offset is
not updated correctly, so move the cur_offset update before
cow_file_range.

  kernel BUG at mm/page-writeback.c:2663!
  Internal error: Oops - BUG: 0 [#1] SMP
  CPU: 3 PID: 31525 Comm: kworker/u8:7 Tainted: P O
  Hardware name: Realtek_RTD1296 (DT)
  Workqueue: writeback wb_workfn (flush-btrfs-1)
  task: ffffffc076db3380 ti: ffffffc02e9ac000 task.ti: ffffffc02e9ac000
  PC is at clear_page_dirty_for_io+0x1bc/0x1e8
  LR is at clear_page_dirty_for_io+0x14/0x1e8
  pc : [<ffffffc00033c91c>] lr : [<ffffffc00033c774>] pstate: 40000145
  sp : ffffffc02e9af4f0
  Process kworker/u8:7 (pid: 31525, stack limit = 0xffffffc02e9ac020)
  Call trace:
  [<ffffffc00033c91c>] clear_page_dirty_for_io+0x1bc/0x1e8
  [<ffffffbffc514674>] extent_clear_unlock_delalloc+0x1e4/0x210 [btrfs]
  [<ffffffbffc4fb168>] run_delalloc_nocow+0x3b8/0x948 [btrfs]
  [<ffffffbffc4fb948>] run_delalloc_range+0x250/0x3a8 [btrfs]
  [<ffffffbffc514c0c>] writepage_delalloc.isra.21+0xbc/0x1d8 [btrfs]
  [<ffffffbffc516048>] __extent_writepage+0xe8/0x248 [btrfs]
  [<ffffffbffc51630c>] extent_write_cache_pages.isra.17+0x164/0x378 [btrfs]
  [<ffffffbffc5185a8>] extent_writepages+0x48/0x68 [btrfs]
  [<ffffffbffc4f5828>] btrfs_writepages+0x20/0x30 [btrfs]
  [<ffffffc00033d758>] do_writepages+0x30/0x88
  [<ffffffc0003ba0f4>] __writeback_single_inode+0x34/0x198
  [<ffffffc0003ba6c4>] writeback_sb_inodes+0x184/0x3c0
  [<ffffffc0003ba96c>] __writeback_inodes_wb+0x6c/0xc0
  [<ffffffc0003bac20>] wb_writeback+0x1b8/0x1c0
  [<ffffffc0003bb0f0>] wb_workfn+0x150/0x250
  [<ffffffc0002b0014>] process_one_work+0x1dc/0x388
  [<ffffffc0002b02f0>] worker_thread+0x130/0x500
  [<ffffffc0002b6344>] kthread+0x10c/0x110
  [<ffffffc000284590>] ret_from_fork+0x10/0x40
  Code: d503201f a9025bb5 a90363b7 f90023b9 (d4210000)

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Robbie Ko <robbieko@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix use-after-free when dumping free space

We were iterating a block group's free space cache rbtree without locking
first the lock that protects it (the free_space_ctl->free_space_offset
rbtree is protected by the free_space_ctl->tree_lock spinlock).

KASAN reported an use-after-free problem when iterating such a rbtree due
to a concurrent rbtree delete:

[ 9520.359168] ==================================================================
[ 9520.359656] BUG: KASAN: use-after-free in rb_next+0x13/0x90
[ 9520.359949] Read of size 8 at addr ffff8800b7ada500 by task btrfs-transacti/1721
[ 9520.360357]
[ 9520.360530] CPU: 4 PID: 1721 Comm: btrfs-transacti Tainted: G             L    4.19.0-rc8-nbor #555
[ 9520.360990] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 9520.362682] Call Trace:
[ 9520.362887]  dump_stack+0xa4/0xf5
[ 9520.363146]  print_address_description+0x78/0x280
[ 9520.363412]  kasan_report+0x263/0x390
[ 9520.363650]  ? rb_next+0x13/0x90
[ 9520.363873]  __asan_load8+0x54/0x90
[ 9520.364102]  rb_next+0x13/0x90
[ 9520.364380]  btrfs_dump_free_space+0x146/0x160 [btrfs]
[ 9520.364697]  dump_space_info+0x2cd/0x310 [btrfs]
[ 9520.364997]  btrfs_reserve_extent+0x1ee/0x1f0 [btrfs]
[ 9520.365310]  __btrfs_prealloc_file_range+0x1cc/0x620 [btrfs]
[ 9520.365646]  ? btrfs_update_time+0x180/0x180 [btrfs]
[ 9520.365923]  ? _raw_spin_unlock+0x27/0x40
[ 9520.366204]  ? btrfs_alloc_data_chunk_ondemand+0x2c0/0x5c0 [btrfs]
[ 9520.366549]  btrfs_prealloc_file_range_trans+0x23/0x30 [btrfs]
[ 9520.366880]  cache_save_setup+0x42e/0x580 [btrfs]
[ 9520.367220]  ? btrfs_check_data_free_space+0xd0/0xd0 [btrfs]
[ 9520.367518]  ? lock_downgrade+0x2f0/0x2f0
[ 9520.367799]  ? btrfs_write_dirty_block_groups+0x11f/0x6e0 [btrfs]
[ 9520.368104]  ? kasan_check_read+0x11/0x20
[ 9520.368349]  ? do_raw_spin_unlock+0xa8/0x140
[ 9520.368638]  btrfs_write_dirty_block_groups+0x2af/0x6e0 [btrfs]
[ 9520.368978]  ? btrfs_start_dirty_block_groups+0x870/0x870 [btrfs]
[ 9520.369282]  ? do_raw_spin_unlock+0xa8/0x140
[ 9520.369534]  ? _raw_spin_unlock+0x27/0x40
[ 9520.369811]  ? btrfs_run_delayed_refs+0x1b8/0x230 [btrfs]
[ 9520.370137]  commit_cowonly_roots+0x4b9/0x610 [btrfs]
[ 9520.370560]  ? commit_fs_roots+0x350/0x350 [btrfs]
[ 9520.370926]  ? btrfs_run_delayed_refs+0x1b8/0x230 [btrfs]
[ 9520.371285]  btrfs_commit_transaction+0x5e5/0x10e0 [btrfs]
[ 9520.371612]  ? btrfs_apply_pending_changes+0x90/0x90 [btrfs]
[ 9520.371943]  ? start_transaction+0x168/0x6c0 [btrfs]
[ 9520.372257]  transaction_kthread+0x21c/0x240 [btrfs]
[ 9520.372537]  kthread+0x1d2/0x1f0
[ 9520.372793]  ? btrfs_cleanup_transaction+0xb50/0xb50 [btrfs]
[ 9520.373090]  ? kthread_park+0xb0/0xb0
[ 9520.373329]  ret_from_fork+0x3a/0x50
[ 9520.373567]
[ 9520.373738] Allocated by task 1804:
[ 9520.373974]  kasan_kmalloc+0xff/0x180
[ 9520.374208]  kasan_slab_alloc+0x11/0x20
[ 9520.374447]  kmem_cache_alloc+0xfc/0x2d0
[ 9520.374731]  __btrfs_add_free_space+0x40/0x580 [btrfs]
[ 9520.375044]  unpin_extent_range+0x4f7/0x7a0 [btrfs]
[ 9520.375383]  btrfs_finish_extent_commit+0x15f/0x4d0 [btrfs]
[ 9520.375707]  btrfs_commit_transaction+0xb06/0x10e0 [btrfs]
[ 9520.376027]  btrfs_alloc_data_chunk_ondemand+0x237/0x5c0 [btrfs]
[ 9520.376365]  btrfs_check_data_free_space+0x81/0xd0 [btrfs]
[ 9520.376689]  btrfs_delalloc_reserve_space+0x25/0x80 [btrfs]
[ 9520.377018]  btrfs_direct_IO+0x42e/0x6d0 [btrfs]
[ 9520.377284]  generic_file_direct_write+0x11e/0x220
[ 9520.377587]  btrfs_file_write_iter+0x472/0xac0 [btrfs]
[ 9520.377875]  aio_write+0x25c/0x360
[ 9520.378106]  io_submit_one+0xaa0/0xdc0
[ 9520.378343]  __se_sys_io_submit+0xfa/0x2f0
[ 9520.378589]  __x64_sys_io_submit+0x43/0x50
[ 9520.378840]  do_syscall_64+0x7d/0x240
[ 9520.379081]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 9520.379387]
[ 9520.379557] Freed by task 1802:
[ 9520.379782]  __kasan_slab_free+0x173/0x260
[ 9520.380028]  kasan_slab_free+0xe/0x10
[ 9520.380262]  kmem_cache_free+0xc1/0x2c0
[ 9520.380544]  btrfs_find_space_for_alloc+0x4cd/0x4e0 [btrfs]
[ 9520.380866]  find_free_extent+0xa99/0x17e0 [btrfs]
[ 9520.381166]  btrfs_reserve_extent+0xd5/0x1f0 [btrfs]
[ 9520.381474]  btrfs_get_blocks_direct+0x60b/0xbd0 [btrfs]
[ 9520.381761]  __blockdev_direct_IO+0x10ee/0x58a1
[ 9520.382059]  btrfs_direct_IO+0x25a/0x6d0 [btrfs]
[ 9520.382321]  generic_file_direct_write+0x11e/0x220
[ 9520.382623]  btrfs_file_write_iter+0x472/0xac0 [btrfs]
[ 9520.382904]  aio_write+0x25c/0x360
[ 9520.383172]  io_submit_one+0xaa0/0xdc0
[ 9520.383416]  __se_sys_io_submit+0xfa/0x2f0
[ 9520.383678]  __x64_sys_io_submit+0x43/0x50
[ 9520.383927]  do_syscall_64+0x7d/0x240
[ 9520.384165]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 9520.384439]
[ 9520.384610] The buggy address belongs to the object at ffff8800b7ada500
                which belongs to the cache btrfs_free_space of size 72
[ 9520.385175] The buggy address is located 0 bytes inside of
                72-byte region [ffff8800b7ada500, ffff8800b7ada548)
[ 9520.385691] The buggy address belongs to the page:
[ 9520.385957] page:ffffea0002deb680 count:1 mapcount:0 mapping:ffff880108a1d700 index:0x0 compound_mapcount: 0
[ 9520.388030] flags: 0x8100(slab|head)
[ 9520.388281] raw: 0000000000008100 ffffea0002deb608 ffffea0002728808 ffff880108a1d700
[ 9520.388722] raw: 0000000000000000 0000000000130013 00000001ffffffff 0000000000000000
[ 9520.389169] page dumped because: kasan: bad access detected
[ 9520.389473]
[ 9520.389658] Memory state around the buggy address:
[ 9520.389943]  ffff8800b7ada400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 9520.390368]  ffff8800b7ada480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 9520.390796] >ffff8800b7ada500: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc
[ 9520.391223]                    ^
[ 9520.391461]  ffff8800b7ada580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 9520.391885]  ffff8800b7ada600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 9520.392313] ==================================================================
[ 9520.392772] BTRFS critical (device vdc): entry offset 2258497536, bytes 131072, bitmap no
[ 9520.393247] BUG: unable to handle kernel NULL pointer dereference at 0000000000000011
[ 9520.393705] PGD 800000010dbab067 P4D 800000010dbab067 PUD 107551067 PMD 0
[ 9520.394059] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[ 9520.394378] CPU: 4 PID: 1721 Comm: btrfs-transacti Tainted: G    B        L    4.19.0-rc8-nbor #555
[ 9520.394858] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 9520.395350] RIP: 0010:rb_next+0x3c/0x90
[ 9520.396461] RSP: 0018:ffff8801074ff780 EFLAGS: 00010292
[ 9520.396762] RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81b5ac4c
[ 9520.397115] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000011
[ 9520.397468] RBP: ffff8801074ff7a0 R08: ffffed0021d64ccc R09: ffffed0021d64ccc
[ 9520.397821] R10: 0000000000000001 R11: ffffed0021d64ccb R12: ffff8800b91e0000
[ 9520.398188] R13: ffff8800a3ceba48 R14: ffff8800b627bf80 R15: 0000000000020000
[ 9520.398555] FS:  0000000000000000(0000) GS:ffff88010eb00000(0000) knlGS:0000000000000000
[ 9520.399007] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 9520.399335] CR2: 0000000000000011 CR3: 0000000106b52000 CR4: 00000000000006a0
[ 9520.399679] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 9520.400023] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 9520.400400] Call Trace:
[ 9520.400648]  btrfs_dump_free_space+0x146/0x160 [btrfs]
[ 9520.400974]  dump_space_info+0x2cd/0x310 [btrfs]
[ 9520.401287]  btrfs_reserve_extent+0x1ee/0x1f0 [btrfs]
[ 9520.401609]  __btrfs_prealloc_file_range+0x1cc/0x620 [btrfs]
[ 9520.401952]  ? btrfs_update_time+0x180/0x180 [btrfs]
[ 9520.402232]  ? _raw_spin_unlock+0x27/0x40
[ 9520.402522]  ? btrfs_alloc_data_chunk_ondemand+0x2c0/0x5c0 [btrfs]
[ 9520.402882]  btrfs_prealloc_file_range_trans+0x23/0x30 [btrfs]
[ 9520.403261]  cache_save_setup+0x42e/0x580 [btrfs]
[ 9520.403570]  ? btrfs_check_data_free_space+0xd0/0xd0 [btrfs]
[ 9520.403871]  ? lock_downgrade+0x2f0/0x2f0
[ 9520.404161]  ? btrfs_write_dirty_block_groups+0x11f/0x6e0 [btrfs]
[ 9520.404481]  ? kasan_check_read+0x11/0x20
[ 9520.404732]  ? do_raw_spin_unlock+0xa8/0x140
[ 9520.405026]  btrfs_write_dirty_block_groups+0x2af/0x6e0 [btrfs]
[ 9520.405375]  ? btrfs_start_dirty_block_groups+0x870/0x870 [btrfs]
[ 9520.405694]  ? do_raw_spin_unlock+0xa8/0x140
[ 9520.405958]  ? _raw_spin_unlock+0x27/0x40
[ 9520.406243]  ? btrfs_run_delayed_refs+0x1b8/0x230 [btrfs]
[ 9520.406574]  commit_cowonly_roots+0x4b9/0x610 [btrfs]
[ 9520.406899]  ? commit_fs_roots+0x350/0x350 [btrfs]
[ 9520.407253]  ? btrfs_run_delayed_refs+0x1b8/0x230 [btrfs]
[ 9520.407589]  btrfs_commit_transaction+0x5e5/0x10e0 [btrfs]
[ 9520.407925]  ? btrfs_apply_pending_changes+0x90/0x90 [btrfs]
[ 9520.408262]  ? start_transaction+0x168/0x6c0 [btrfs]
[ 9520.408582]  transaction_kthread+0x21c/0x240 [btrfs]
[ 9520.408870]  kthread+0x1d2/0x1f0
[ 9520.409138]  ? btrfs_cleanup_transaction+0xb50/0xb50 [btrfs]
[ 9520.409440]  ? kthread_park+0xb0/0xb0
[ 9520.409682]  ret_from_fork+0x3a/0x50
[ 9520.410508] Dumping ftrace buffer:
[ 9520.410764]    (ftrace buffer empty)
[ 9520.411007] CR2: 0000000000000011
[ 9520.411297] ---[ end trace 01a0863445cf360a ]---
[ 9520.411568] RIP: 0010:rb_next+0x3c/0x90
[ 9520.412644] RSP: 0018:ffff8801074ff780 EFLAGS: 00010292
[ 9520.412932] RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81b5ac4c
[ 9520.413274] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000011
[ 9520.413616] RBP: ffff8801074ff7a0 R08: ffffed0021d64ccc R09: ffffed0021d64ccc
[ 9520.414007] R10: 0000000000000001 R11: ffffed0021d64ccb R12: ffff8800b91e0000
[ 9520.414349] R13: ffff8800a3ceba48 R14: ffff8800b627bf80 R15: 0000000000020000
[ 9520.416074] FS:  0000000000000000(0000) GS:ffff88010eb00000(0000) knlGS:0000000000000000
[ 9520.416536] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 9520.416848] CR2: 0000000000000011 CR3: 0000000106b52000 CR4: 00000000000006a0
[ 9520.418477] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 9520.418846] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 9520.419204] Kernel panic - not syncing: Fatal exception
[ 9520.419666] Dumping ftrace buffer:
[ 9520.419930]    (ftrace buffer empty)
[ 9520.420168] Kernel Offset: disabled
[ 9520.420406] ---[ end Kernel panic - not syncing: Fatal exception ]---

Fix this by acquiring the respective lock before iterating the rbtree.

Reported-by: Nikolay Borisov <nborisov@suse.com>
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix use-after-free during inode eviction

At inode.c:evict_inode_truncate_pages(), when we iterate over the
inode's extent states, we access an extent state record's "state" field
after we unlocked the inode's io tree lock. This can lead to a
use-after-free issue because after we unlock the io tree that extent
state record might have been freed due to being merged into another
adjacent extent state record (a previous inflight bio for a read
operation finished in the meanwhile which unlocked a range in the io
tree and cause a merge of extent state records, as explained in the
comment before the while loop added in commit 6ca0709756710 ("Btrfs: fix
hang during inode eviction due to concurrent readahead")).

Fix this by keeping a copy of the extent state's flags in a local
variable and using it after unlocking the io tree.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201189
Fixes: b9d0b38928e2 ("btrfs: Add handler for invalidate page")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: move the dio_sem higher up the callchain

We're getting a lockdep splat because we take the dio_sem under the
log_mutex.  What we really need is to protect fsync() from logging an
extent map for an extent we never waited on higher up, so just guard the
whole thing with dio_sem.

======================================================
WARNING: possible circular locking dependency detected
4.18.0-rc4-xfstests-00025-g5de5edbaf1d4 #411 Not tainted
------------------------------------------------------
aio-dio-invalid/30928 is trying to acquire lock:
0000000092621cfd (&mm->mmap_sem){++++}, at: get_user_pages_unlocked+0x5a/0x1e0

but task is already holding lock:
00000000cefe6b35 (&ei->dio_sem){++++}, at: btrfs_direct_IO+0x3be/0x400

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #5 (&ei->dio_sem){++++}:
       lock_acquire+0xbd/0x220
       down_write+0x51/0xb0
       btrfs_log_changed_extents+0x80/0xa40
       btrfs_log_inode+0xbaf/0x1000
       btrfs_log_inode_parent+0x26f/0xa80
       btrfs_log_dentry_safe+0x50/0x70
       btrfs_sync_file+0x357/0x540
       do_fsync+0x38/0x60
       __ia32_sys_fdatasync+0x12/0x20
       do_fast_syscall_32+0x9a/0x2f0
       entry_SYSENTER_compat+0x84/0x96

-> #4 (&ei->log_mutex){+.+.}:
       lock_acquire+0xbd/0x220
       __mutex_lock+0x86/0xa10
       btrfs_record_unlink_dir+0x2a/0xa0
       btrfs_unlink+0x5a/0xc0
       vfs_unlink+0xb1/0x1a0
       do_unlinkat+0x264/0x2b0
       do_fast_syscall_32+0x9a/0x2f0
       entry_SYSENTER_compat+0x84/0x96

-> #3 (sb_internal#2){.+.+}:
       lock_acquire+0xbd/0x220
       __sb_start_write+0x14d/0x230
       start_transaction+0x3e6/0x590
       btrfs_evict_inode+0x475/0x640
       evict+0xbf/0x1b0
       btrfs_run_delayed_iputs+0x6c/0x90
       cleaner_kthread+0x124/0x1a0
       kthread+0x106/0x140
       ret_from_fork+0x3a/0x50

-> #2 (&fs_info->cleaner_delayed_iput_mutex){+.+.}:
       lock_acquire+0xbd/0x220
       __mutex_lock+0x86/0xa10
       btrfs_alloc_data_chunk_ondemand+0x197/0x530
       btrfs_check_data_free_space+0x4c/0x90
       btrfs_delalloc_reserve_space+0x20/0x60
       btrfs_page_mkwrite+0x87/0x520
       do_page_mkwrite+0x31/0xa0
       __handle_mm_fault+0x799/0xb00
       handle_mm_fault+0x7c/0xe0
       __do_page_fault+0x1d3/0x4a0
       async_page_fault+0x1e/0x30

-> #1 (sb_pagefaults){.+.+}:
       lock_acquire+0xbd/0x220
       __sb_start_write+0x14d/0x230
       btrfs_page_mkwrite+0x6a/0x520
       do_page_mkwrite+0x31/0xa0
       __handle_mm_fault+0x799/0xb00
       handle_mm_fault+0x7c/0xe0
       __do_page_fault+0x1d3/0x4a0
       async_page_fault+0x1e/0x30

-> #0 (&mm->mmap_sem){++++}:
       __lock_acquire+0x42e/0x7a0
       lock_acquire+0xbd/0x220
       down_read+0x48/0xb0
       get_user_pages_unlocked+0x5a/0x1e0
       get_user_pages_fast+0xa4/0x150
       iov_iter_get_pages+0xc3/0x340
       do_direct_IO+0xf93/0x1d70
       __blockdev_direct_IO+0x32d/0x1c20
       btrfs_direct_IO+0x227/0x400
       generic_file_direct_write+0xcf/0x180
       btrfs_file_write_iter+0x308/0x58c
       aio_write+0xf8/0x1d0
       io_submit_one+0x3a9/0x620
       __ia32_compat_sys_io_submit+0xb2/0x270
       do_int80_syscall_32+0x5b/0x1a0
       entry_INT80_compat+0x88/0xa0

other info that might help us debug this:

Chain exists of:
  &mm->mmap_sem --> &ei->log_mutex --> &ei->dio_sem

Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ei->dio_sem);
                               lock(&ei->log_mutex);
                               lock(&ei->dio_sem);
  lock(&mm->mmap_sem);

*** DEADLOCK ***

1 lock held by aio-dio-invalid/30928:
#0: 00000000cefe6b35 (&ei->dio_sem){++++}, at: btrfs_direct_IO+0x3be/0x400

stack backtrace:
CPU: 0 PID: 30928 Comm: aio-dio-invalid Not tainted 4.18.0-rc4-xfstests-00025-g5de5edbaf1d4 #411
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
Call Trace:
dump_stack+0x7c/0xbb
print_circular_bug.isra.37+0x297/0x2a4
check_prev_add.constprop.45+0x781/0x7a0
? __lock_acquire+0x42e/0x7a0
validate_chain.isra.41+0x7f0/0xb00
__lock_acquire+0x42e/0x7a0
lock_acquire+0xbd/0x220
? get_user_pages_unlocked+0x5a/0x1e0
down_read+0x48/0xb0
? get_user_pages_unlocked+0x5a/0x1e0
get_user_pages_unlocked+0x5a/0x1e0
get_user_pages_fast+0xa4/0x150
iov_iter_get_pages+0xc3/0x340
do_direct_IO+0xf93/0x1d70
? __alloc_workqueue_key+0x358/0x490
? __blockdev_direct_IO+0x14b/0x1c20
__blockdev_direct_IO+0x32d/0x1c20
? btrfs_run_delalloc_work+0x40/0x40
? can_nocow_extent+0x490/0x490
? kvm_clock_read+0x1f/0x30
? can_nocow_extent+0x490/0x490
? btrfs_run_delalloc_work+0x40/0x40
btrfs_direct_IO+0x227/0x400
? btrfs_run_delalloc_work+0x40/0x40
generic_file_direct_write+0xcf/0x180
btrfs_file_write_iter+0x308/0x58c
aio_write+0xf8/0x1d0
? kvm_clock_read+0x1f/0x30
? __might_fault+0x3e/0x90
io_submit_one+0x3a9/0x620
? io_submit_one+0xe5/0x620
__ia32_compat_sys_io_submit+0xb2/0x270
do_int80_syscall_32+0x5b/0x1a0
entry_INT80_compat+0x88/0xa0

CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: don't run delayed_iputs in commit

This could result in a really bad case where we do something like

evict
  evict_refill_and_join
    btrfs_commit_transaction
      btrfs_run_delayed_iputs
        evict
          evict_refill_and_join
            btrfs_commit_transaction
... forever

We have plenty of other places where we run delayed iputs that are much
safer, let those do the work.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix insert_reserved error handling

We were not handling the reserved byte accounting properly for data
references. Metadata was fine, if it errored out the error paths would
free the bytes_reserved count and pin the extent, but it even missed one
of the error cases. So instead move this handling up into
run_one_delayed_ref so we are sure that both cases are properly cleaned
up in case of a transaction abort.

CC: stable@vger.kernel.org # 4.18+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: only free reserved extent if we didn't insert it

When we insert the file extent once the ordered extent completes we free
the reserved extent reservation as it'll have been migrated to the
bytes_used counter. However if we error out after this step we'll still
clear the reserved extent reservation, resulting in a negative
accounting of the reserved bytes for the block group and space info.
Fix this by only doing the free if we didn't successfully insert a file
extent for this extent.

CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: don't use ctl->free_space for max_extent_size

max_extent_size is supposed to be the largest contiguous range for the
space info, and ctl->free_space is the total free space in the block
group. We need to keep track of these separately and _only_ use the
max_free_space if we don't have a max_extent_size, as that means our
original request was too large to search any of the block groups for and
therefore wouldn't have a max_extent_size set.

CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: set max_extent_size properly

We can't use entry->bytes if our entry is a bitmap entry, we need to use
entry->max_extent_size in that case. Fix up all the logic to make this
consistent.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: reset max_extent_size properly

If we use up our block group before allocating a new one we'll easily
get a max_extent_size that's set really really low, which will result in
a lot of fragmentation. We need to make sure we're resetting the
max_extent_size when we add a new chunk or add new space.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

MAINTAINERS: update my email address for btrfs

My work email is completely useless, switch it to my personal address so
I get emails on a account I actually pay attention to.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: delayed-ref: extract find_first_ref_head from find_ref_head

The find_ref_head shouldn't return the first entry even if no exact match
is found. So move the hidden behavior to higher level.

Besides, remove the useless local variables in the btrfs_select_ref_head.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
[ reformat comment ]
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix deadlock when writing out free space caches

When writing out a block group free space cache we can end deadlocking
with ourselves on an extent buffer lock resulting in a warning like the
following:

  [245043.379979] WARNING: CPU: 4 PID: 2608 at fs/btrfs/locking.c:251 btrfs_tree_lock+0x1be/0x1d0 [btrfs]
  [245043.392792] CPU: 4 PID: 2608 Comm: btrfs-transacti Tainted: G
    W I      4.16.8 #1
  [245043.395489] RIP: 0010:btrfs_tree_lock+0x1be/0x1d0 [btrfs]
  [245043.396791] RSP: 0018:ffffc9000424b840 EFLAGS: 00010246
  [245043.398093] RAX: 0000000000000a30 RBX: ffff8807e20a3d20 RCX: 0000000000000001
  [245043.399414] RDX: 0000000000000001 RSI: 0000000000000002 RDI: ffff8807e20a3d20
  [245043.400732] RBP: 0000000000000001 R08: ffff88041f39a700 R09: ffff880000000000
  [245043.402021] R10: 0000000000000040 R11: ffff8807e20a3d20 R12: ffff8807cb220630
  [245043.403296] R13: 0000000000000001 R14: ffff8807cb220628 R15: ffff88041fbdf000
  [245043.404780] FS:  0000000000000000(0000) GS:ffff88082fc80000(0000) knlGS:0000000000000000
  [245043.406050] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [245043.407321] CR2: 00007fffdbdb9f10 CR3: 0000000001c09005 CR4: 00000000000206e0
  [245043.408670] Call Trace:
  [245043.409977]  btrfs_search_slot+0x761/0xa60 [btrfs]
  [245043.411278]  btrfs_insert_empty_items+0x62/0xb0 [btrfs]
  [245043.412572]  btrfs_insert_item+0x5b/0xc0 [btrfs]
  [245043.413922]  btrfs_create_pending_block_groups+0xfb/0x1e0 [btrfs]
  [245043.415216]  do_chunk_alloc+0x1e5/0x2a0 [btrfs]
  [245043.416487]  find_free_extent+0xcd0/0xf60 [btrfs]
  [245043.417813]  btrfs_reserve_extent+0x96/0x1e0 [btrfs]
  [245043.419105]  btrfs_alloc_tree_block+0xfb/0x4a0 [btrfs]
  [245043.420378]  __btrfs_cow_block+0x127/0x550 [btrfs]
  [245043.421652]  btrfs_cow_block+0xee/0x190 [btrfs]
  [245043.422979]  btrfs_search_slot+0x227/0xa60 [btrfs]
  [245043.424279]  ? btrfs_update_inode_item+0x59/0x100 [btrfs]
  [245043.425538]  ? iput+0x72/0x1e0
  [245043.426798]  write_one_cache_group.isra.49+0x20/0x90 [btrfs]
  [245043.428131]  btrfs_start_dirty_block_groups+0x102/0x420 [btrfs]
  [245043.429419]  btrfs_commit_transaction+0x11b/0x880 [btrfs]
  [245043.430712]  ? start_transaction+0x8e/0x410 [btrfs]
  [245043.432006]  transaction_kthread+0x184/0x1a0 [btrfs]
  [245043.433341]  kthread+0xf0/0x130
  [245043.434628]  ? btrfs_cleanup_transaction+0x4e0/0x4e0 [btrfs]
  [245043.435928]  ? kthread_create_worker_on_cpu+0x40/0x40
  [245043.437236]  ret_from_fork+0x1f/0x30
  [245043.441054] ---[ end trace 15abaa2aaf36827f ]---

This is because at write_one_cache_group() when we are COWing a leaf from
the extent tree we end up allocating a new block group (chunk) and,
because we have hit a threshold on the number of bytes reserved for system
chunks, we attempt to finalize the creation of new block groups from the
current transaction, by calling btrfs_create_pending_block_groups().
However here we also need to modify the extent tree in order to insert
a block group item, and if the location for this new block group item
happens to be in the same leaf that we were COWing earlier, we deadlock
since btrfs_search_slot() tries to write lock the extent buffer that we
locked before at write_one_cache_group().

We have already hit similar cases in the past and commit d9a0540a79f8
("Btrfs: fix deadlock when finalizing block group creation") fixed some
of those cases by delaying the creation of pending block groups at the
known specific spots that could lead to a deadlock. This change reworks
that commit to be more generic so that we don't have to add similar logic
to every possible path that can lead to a deadlock. This is done by
making __btrfs_cow_block() disallowing the creation of new block groups
(setting the transaction's can_flush_pending_bgs to false) before it
attempts to allocate a new extent buffer for either the extent, chunk or
device trees, since those are the trees that pending block creation
modifies. Once the new extent buffer is allocated, it allows creation of
pending block groups to happen again.

This change depends on a recent patch from Josef which is not yet in
Linus' tree, named "btrfs: make sure we create all new block groups" in
order to avoid occasional warnings at btrfs_trans_release_chunk_metadata().

Fixes: d9a0540a79f8 ("Btrfs: fix deadlock when finalizing block group creation")
CC: stable@vger.kernel.org # 4.4+
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199753
Link: https://lore.kernel.org/linux-btrfs/CAJtFHUTHna09ST-_EEiyWmDH6gAqS6wa=zMNMBsifj8ABu99cw@mail.gmail.com/
Reported-by: E V <eliventer@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix assertion on fsync of regular file when using no-holes feature

When using the NO_HOLES feature and logging a regular file, we were
expecting that if we find an inline extent, that either its size in RAM
(uncompressed and unenconded) matches the size of the file or if it does
not, that it matches the sector size and it represents compressed data.
This assertion does not cover a case where the length of the inline extent
is smaller than the sector size and also smaller the file's size, such
case is possible through fallocate. Example:

  $ mkfs.btrfs -f -O no-holes /dev/sdb
  $ mount /dev/sdb /mnt

  $ xfs_io -f -c "pwrite -S 0xb60 0 21" /mnt/foobar
  $ xfs_io -c "falloc 40 40" /mnt/foobar
  $ xfs_io -c "fsync" /mnt/foobar

In the above example we trigger the assertion because the inline extent's
length is 21 bytes while the file size is 80 bytes. The fallocate() call
merely updated the file's size and did not touch the existing inline
extent, as expected.

So fix this by adjusting the assertion so that an inline extent length
smaller than the file size is valid if the file size is smaller than the
filesystem's sector size.

A test case for fstests follows soon.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Fixes: a89ca6f24ffe ("Btrfs: fix fsync after truncate when no_holes feature is enabled")
CC: stable@vger.kernel.org # 4.14+
Link: https://lore.kernel.org/linux-btrfs/CAE5jQCfRSBC7n4pUTFJcmHh109=gwyT9mFkCOL+NKfzswmR=_Q@mail.gmail.com/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix null pointer dereference on compressed write path error

At inode.c:compress_file_range(), under the "free_pages_out" label, we can
end up dereferencing the "pages" pointer when it has a NULL value. This
case happens when "start" has a value of 0 and we fail to allocate memory
for the "pages" pointer. When that happens we jump to the "cont" label and
then enter the "if (start == 0)" branch where we immediately call the
cow_file_range_inline() function. If that function returns 0 (success
creating an inline extent) or an error (like -ENOMEM for example) we jump
to the "free_pages_out" label and then access "pages[i]" leading to a NULL
pointer dereference, since "nr_pages" has a value greater than zero at
that point.

Fix this by setting "nr_pages" to 0 when we fail to allocate memory for
the "pages" pointer.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201119
Fixes: 771ed689d2cd ("Btrfs: Optimize compressed writeback and reads")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: switch return_bigger to bool in find_ref_head

Using bool is more suitable than int here, and add the comment about the
return_bigger.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove fs_info from btrfs_should_throttle_delayed_refs

The avg_delayed_ref_runtime can be referenced from the transaction
handle.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove fs_info from btrfs_check_space_for_delayed_refs

It can be referenced from the transaction handle.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: delayed-ref: pass delayed_refs directly to btrfs_delayed_ref_lock

Since trans is only used for referring to delayed_refs, there is no need
to pass it instead of delayed_refs to btrfs_delayed_ref_lock().

No functional change.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: delayed-ref: pass delayed_refs directly to btrfs_select_ref_head

Since trans is only used for referring to delayed_refs, there is no need
to pass it instead of delayed_refs to btrfs_select_ref_head(). No
functional change.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: qgroup: move the qgroup->members check out from (!qgroup)'s else branch

There is no reason to put this check in (!qgroup)'s else branch because
if qgroup is null, it will goto out directly. So move it out to reduce
indentation level. No functional change.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: relocation: Remove redundant tree level check

Commit 581c1760415c ("btrfs: Validate child tree block's level and first
key") has made tree block level check mandatory.

So if tree block level doesn't match, we won't get a valid extent
buffer. The extra WARN_ON() check can be removed completely.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: relocation: Cleanup while loop using rbtree_postorder_for_each_entry_safe

And add one line comment explaining what we're doing for each loop.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: qgroup: Avoid calling qgroup functions if qgroup is not enabled

Some qgroup trace events like btrfs_qgroup_release_data() and
btrfs_qgroup_free_delayed_ref() can still be triggered even if qgroup is
not enabled.

This is caused by the lack of qgroup status check before calling some
qgroup functions.  Thankfully the functions can handle quota disabled
case well and just do nothing for qgroup disabled case.

This patch will do earlier check before triggering related trace events.

And for enabled <-> disabled race case:

1) For enabled->disabled case
   Disable will wipe out all qgroups data including reservation and
   excl/rfer. Even if we leak some reservation or numbers, it will
   still be cleared, so nothing will go wrong.

2) For disabled -> enabled case
   Current btrfs_qgroup_release_data() will use extent_io tree to ensure
   we won't underflow reservation. And for delayed_ref we use
   head->qgroup_reserved to record the reserved space, so in that case
   head->qgroup_reserved should be 0 and we won't underflow.

CC: stable@vger.kernel.org # 4.14+
Reported-by: Chris Murphy <lists@colorremedies.com>
Link: https://lore.kernel.org/linux-btrfs/CAJCQCtQau7DtuUUeycCkZ36qjbKuxNzsgqJ7+sJ6W0dK_NLE3w@mail.gmail.com/
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix wrong dentries after fsync of file that got its parent replaced

In a scenario like the following:

  mkdir /mnt/A               # inode 258
  mkdir /mnt/B               # inode 259
  touch /mnt/B/bar           # inode 260

  sync

  mv /mnt/B/bar /mnt/A/bar
  mv -T /mnt/A /mnt/B
  fsync /mnt/B/bar

  <power fail>

After replaying the log we end up with file bar having 2 hard links, both
with the name 'bar' and one in the directory with inode number 258 and the
other in the directory with inode number 259. Also, we end up with the
directory inode 259 still existing and with the directory inode 258 still
named as 'A', instead of 'B'. In this scenario, file 'bar' should only
have one hard link, located at directory inode 258, the directory inode
259 should not exist anymore and the name for directory inode 258 should
be 'B'.

This incorrect behaviour happens because when attempting to log the old
parents of an inode, we skip any parents that no longer exist. Fix this
by forcing a full commit if an old parent no longer exists.

A test case for fstests follows soon.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix warning when replaying log after fsync of a tmpfile

When replaying a log which contains a tmpfile (which necessarily has a
link count of 0) we end up calling inc_nlink(), at
fs/btrfs/tree-log.c:replay_one_buffer(), which produces a warning like
the following:

  [195191.943673] WARNING: CPU: 0 PID: 6924 at fs/inode.c:342 inc_nlink+0x33/0x40
  [195191.943723] CPU: 0 PID: 6924 Comm: mount Not tainted 4.19.0-rc6-btrfs-next-38 #1
  [195191.943724] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
  [195191.943726] RIP: 0010:inc_nlink+0x33/0x40
  [195191.943728] RSP: 0018:ffffb96e425e3870 EFLAGS: 00010246
  [195191.943730] RAX: 0000000000000000 RBX: ffff8c0d1e6af4f0 RCX: 0000000000000006
  [195191.943731] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8c0d1e6af4f0
  [195191.943731] RBP: 0000000000000097 R08: 0000000000000001 R09: 0000000000000000
  [195191.943732] R10: 0000000000000000 R11: 0000000000000000 R12: ffffb96e425e3a60
  [195191.943733] R13: ffff8c0d10cff0c8 R14: ffff8c0d0d515348 R15: ffff8c0d78a1b3f8
  [195191.943735] FS:  00007f570ee24480(0000) GS:ffff8c0dfb200000(0000) knlGS:0000000000000000
  [195191.943736] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [195191.943737] CR2: 00005593286277c8 CR3: 00000000bb8f2006 CR4: 00000000003606f0
  [195191.943739] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  [195191.943740] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  [195191.943741] Call Trace:
  [195191.943778]  replay_one_buffer+0x797/0x7d0 [btrfs]
  [195191.943802]  walk_up_log_tree+0x1c1/0x250 [btrfs]
  [195191.943809]  ? rcu_read_lock_sched_held+0x3f/0x70
  [195191.943825]  walk_log_tree+0xae/0x1d0 [btrfs]
  [195191.943840]  btrfs_recover_log_trees+0x1d7/0x4d0 [btrfs]
  [195191.943856]  ? replay_dir_deletes+0x280/0x280 [btrfs]
  [195191.943870]  open_ctree+0x1c3b/0x22a0 [btrfs]
  [195191.943887]  btrfs_mount_root+0x6b4/0x800 [btrfs]
  [195191.943894]  ? rcu_read_lock_sched_held+0x3f/0x70
  [195191.943899]  ? pcpu_alloc+0x55b/0x7c0
  [195191.943906]  ? mount_fs+0x3b/0x140
  [195191.943908]  mount_fs+0x3b/0x140
  [195191.943912]  ? __init_waitqueue_head+0x36/0x50
  [195191.943916]  vfs_kern_mount+0x62/0x160
  [195191.943927]  btrfs_mount+0x134/0x890 [btrfs]
  [195191.943936]  ? rcu_read_lock_sched_held+0x3f/0x70
  [195191.943938]  ? pcpu_alloc+0x55b/0x7c0
  [195191.943943]  ? mount_fs+0x3b/0x140
  [195191.943952]  ? btrfs_remount+0x570/0x570 [btrfs]
  [195191.943954]  mount_fs+0x3b/0x140
  [195191.943956]  ? __init_waitqueue_head+0x36/0x50
  [195191.943960]  vfs_kern_mount+0x62/0x160
  [195191.943963]  do_mount+0x1f9/0xd40
  [195191.943967]  ? memdup_user+0x4b/0x70
  [195191.943971]  ksys_mount+0x7e/0xd0
  [195191.943974]  __x64_sys_mount+0x21/0x30
  [195191.943977]  do_syscall_64+0x60/0x1b0
  [195191.943980]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [195191.943983] RIP: 0033:0x7f570e4e524a
  [195191.943986] RSP: 002b:00007ffd83589478 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
  [195191.943989] RAX: ffffffffffffffda RBX: 0000563f335b2060 RCX: 00007f570e4e524a
  [195191.943990] RDX: 0000563f335b2240 RSI: 0000563f335b2280 RDI: 0000563f335b2260
  [195191.943992] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000020
  [195191.943993] R10: 00000000c0ed0000 R11: 0000000000000206 R12: 0000563f335b2260
  [195191.943994] R13: 0000563f335b2240 R14: 0000000000000000 R15: 00000000ffffffff
  [195191.944002] irq event stamp: 8688
  [195191.944010] hardirqs last  enabled at (8687): [<ffffffff9cb004c3>] console_unlock+0x503/0x640
  [195191.944012] hardirqs last disabled at (8688): [<ffffffff9ca037dd>] trace_hardirqs_off_thunk+0x1a/0x1c
  [195191.944018] softirqs last  enabled at (8638): [<ffffffff9cc0a5d1>] __set_page_dirty_nobuffers+0x101/0x150
  [195191.944020] softirqs last disabled at (8634): [<ffffffff9cc26bbe>] wb_wakeup_delayed+0x2e/0x60
  [195191.944022] ---[ end trace 5d6e873a9a0b811a ]---

This happens because the inode does not have the flag I_LINKABLE set,
which is a runtime only flag, not meant to be persisted, set when the
inode is created through open(2) if the flag O_EXCL is not passed to it.
Except for the warning, there are no other consequences (like corruptions
or metadata inconsistencies).

Since it's pointless to replay a tmpfile as it would be deleted in a
later phase of the log replay procedure (it has a link count of 0), fix
this by not logging tmpfiles and if a tmpfile is found in a log (created
by a kernel without this change), skip the replay of the inode.

A test case for fstests follows soon.

Fixes: 471d557afed1 ("Btrfs: fix loss of prealloc extents past i_size after fsync log replay")
CC: stable@vger.kernel.org # 4.18+
Reported-by: Martin Steigerwald <martin@lichtvoll.de>
Link: https://lore.kernel.org/linux-btrfs/3666619.NTnn27ZJZE@merkaba/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: drop min_size from evict_refill_and_join

We don't need it, rsv->size is set once and never changes throughout
its lifetime, so just use that for the reserve size.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: assert on non-empty delayed iputs

I ran into an issue where there was some reference being held on an
inode that I couldn't track. This assert wasn't triggered, but it at
least rules out we're doing something stupid.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: make sure we create all new block groups

Allocating new chunks modifies both the extent and chunk tree, which can
trigger new chunk allocations. So instead of doing list_for_each_safe,
just do while (!list_empty()) so we make sure we don't exit with other
pending bg's still on our list.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: reset max_extent_size on clear in a bitmap

We need to clear the max_extent_size when we clear bits from a bitmap
since it could have been from the range that contains the
max_extent_size.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: protect space cache inode alloc with GFP_NOFS

If we're allocating a new space cache inode it's likely going to be
under a transaction handle, so we need to use memalloc_nofs_save() in
order to avoid deadlocks, and more importantly lockdep messages that
make xfstests fail.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: release metadata before running delayed refs

We want to release the unused reservation we have since it refills the
delayed refs reserve, which will make everything go smoother when
running the delayed refs if we're short on our reservation.

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: kill btrfs_clear_path_blocking

Btrfs's btree locking has two modes, spinning mode and blocking mode,
while searching btree, locking is always acquired in spinning mode and
then converted to blocking mode if necessary, and in some hot paths we may
switch the locking back to spinning mode by btrfs_clear_path_blocking().

When acquiring locks, both of reader and writer need to wait for blocking
readers and writers to complete before doing read_lock()/write_lock().

The problem is that btrfs_clear_path_blocking() needs to switch nodes
in the path to blocking mode at first (by btrfs_set_path_blocking) to
make lockdep happy before doing its actual clearing blocking job.

When switching to blocking mode from spinning mode, it consists of

step 1) bumping up blocking readers counter and
step 2) read_unlock()/write_unlock(),

this has caused serious ping-pong effect if there're a great amount of
concurrent readers/writers, as waiters will be woken up and go to
sleep immediately.

1) Killing this kind of ping-pong results in a big improvement in my 1600k
files creation script,

MNT=/mnt/btrfs
mkfs.btrfs -f /dev/sdf
mount /dev/def $MNT
time fsmark  -D  10000  -S0  -n  100000  -s  0  -L  1 -l /tmp/fs_log.txt \
        -d  $MNT/0  -d  $MNT/1 \
        -d  $MNT/2  -d  $MNT/3 \
        -d  $MNT/4  -d  $MNT/5 \
        -d  $MNT/6  -d  $MNT/7 \
        -d  $MNT/8  -d  $MNT/9 \
        -d  $MNT/10  -d  $MNT/11 \
        -d  $MNT/12  -d  $MNT/13 \
        -d  $MNT/14  -d  $MNT/15

w/o patch:
real    2m27.307s
user    0m12.839s
sys     13m42.831s

w/ patch:
real    1m2.273s
user    0m15.802s
sys     8m16.495s

1.1) latency histogram from funclatency[1]

Overall with the patch, there're ~50% less write lock acquisition and
the 95% max latency that write lock takes also reduces to ~100ms from
>500ms.

--------------------------------------------
w/o patch:
--------------------------------------------
Function = btrfs_tree_lock
     msecs               : count     distribution
         0 -> 1          : 2385222  |****************************************|
         2 -> 3          : 37147    |                                        |
         4 -> 7          : 20452    |                                        |
         8 -> 15         : 13131    |                                        |
        16 -> 31         : 3877     |                                        |
        32 -> 63         : 3900     |                                        |
        64 -> 127        : 2612     |                                        |
       128 -> 255        : 974      |                                        |
       256 -> 511        : 165      |                                        |
       512 -> 1023       : 13       |                                        |

Function = btrfs_tree_read_lock
     msecs               : count     distribution
         0 -> 1          : 6743860  |****************************************|
         2 -> 3          : 2146     |                                        |
         4 -> 7          : 190      |                                        |
         8 -> 15         : 38       |                                        |
        16 -> 31         : 4        |                                        |

--------------------------------------------
w/ patch:
--------------------------------------------
Function = btrfs_tree_lock
     msecs               : count     distribution
         0 -> 1          : 1318454  |****************************************|
         2 -> 3          : 6800     |                                        |
         4 -> 7          : 3664     |                                        |
         8 -> 15         : 2145     |                                        |
        16 -> 31         : 809      |                                        |
        32 -> 63         : 219      |                                        |
        64 -> 127        : 10       |                                        |

Function = btrfs_tree_read_lock
     msecs               : count     distribution
         0 -> 1          : 6854317  |****************************************|
         2 -> 3          : 2383     |                                        |
         4 -> 7          : 601      |                                        |
         8 -> 15         : 92       |                                        |

2) dbench also proves the improvement,
dbench -t 120 -D /mnt/btrfs 16

w/o patch:
Throughput 158.363 MB/sec

w/ patch:
Throughput 449.52 MB/sec

3) xfstests didn't show any additional failures.

One thing to note is that callers may set path->leave_spinning to have
all nodes in the path stay in spinning mode, which means callers are
ready to not sleep before releasing the path, but it won't cause
problems if they don't want to sleep in blocking mode.

[1]: https://github.com/iovisor/bcc/blob/master/tools/funclatency.py

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: dev-replace: remove pointless assert in write unlock

The value of blocking_readers is increased only when the lock is taken
for read, no way we can fail the condition with the write lock.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: dev-replace: move replace members out of fs_info

The replace_wait and bio_counter were mistakenly added to fs_info in
commit c404e0dc2c843b154f ("Btrfs: fix use-after-free in the finishing
procedure of the device replace"), but they logically belong to
fs_info::dev_replace. Besides, bio_counter is a very generic name and is
confusing in bare fs_info context.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: dev-replace: avoid useless lock on error handling path

The exit sequence in btrfs_dev_replace_start does not allow to simply
add a label to the right place so the error handling after starting
transaction failure jumps there. Currently there's a lock that pairs
with the unlock in the section, which is unnecessary and only raises
questions. Add a variable to track the locking status and avoid the
extra locking.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: open code btrfs_after_dev_replace_commit

Too trivial, the purpose can be simply documented in a comment.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: open code btrfs_dev_replace_stats_inc

The wrapper is too trivial, open coding does not make it less readable.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: open code btrfs_dev_replace_clear_lock_blocking

There's a single caller and the function name does not say it's actually
taking the lock, so open coding makes it more explicit.

For now, btrfs_dev_replace_read_lock is used instead of read_lock so
it's paired with the unlocking wrapper in the same block.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove btrfs_dev_replace::read_locks

This member seems to be copied from the extent_buffer locking scheme and
is at least used to assert that the read lock/unlock is properly nested.
In some way. While the _inc/_dec are called inside the read lock
section, the asserts are both inside and outside, so the ordering is not
guaranteed and we can see read/inc/dec ordered in any way
(theoretically).

A missing call of btrfs_dev_replace_clear_lock_blocking could cause
unexpected read_locks count, so this at least looks like a valid
assertion, but this will become unnecessary with later updates.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: tree-checker: Check level for leaves and nodes

Although we have tree level check at tree read runtime, it's completely
based on its parent level.
We still need to do accurate level check to avoid invalid tree blocks
sneak into kernel space.

The check itself is simple, for leaf its level should always be 0.
For nodes its level should be in range [1, BTRFS_MAX_LEVEL - 1].

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: qgroup: Only trace data extents in leaves if we're relocating data block group

For qgroup_trace_extent_swap(), if we find one leaf that needs to be
traced, we will also iterate all file extents and trace them.

This is OK if we're relocating data block groups, but if we're
relocating metadata block groups, balance code itself has ensured that
both subtree of file tree and reloc tree contain the same contents.

That's to say, if we're relocating metadata block groups, all file
extents in reloc and file tree should match, thus no need to trace them.
This should reduce the total number of dirty extents processed in metadata
block group balance.

[[Benchmark]] (with all previous enhancement)
Hardware:
VM 4G vRAM, 8 vCPUs,
disk is using 'unsafe' cache mode,
backing device is SAMSUNG 850 evo SSD.
Host has 16G ram.

Mkfs parameter:
--nodesize 4K (To bump up tree size)

Initial subvolume contents:
4G data copied from /usr and /lib.
(With enough regular small files)

Snapshots:
16 snapshots of the original subvolume.
each snapshot has 3 random files modified.

balance parameter:
-m

So the content should be pretty similar to a real world root fs layout.

                     | v4.19-rc1    | w/ patchset    | diff (*)
---------------------------------------------------------------
relocated extents    | 22929        | 22851          | -0.3%
qgroup dirty extents | 227757       | 140886         | -38.1%
time (sys)           | 65.253s      | 37.464s        | -42.6%
time (real)          | 74.032s      | 44.722s        | -39.6%

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: qgroup: Don't trace subtree if we're dropping reloc tree

Reloc tree doesn't contribute to qgroup numbers, as we have accounted
them at balance time (see replace_path()).

Skipping the unneeded subtree tracing should reduce the overhead.

[[Benchmark]]
Hardware:
VM 4G vRAM, 8 vCPUs,
disk is using 'unsafe' cache mode,
backing device is SAMSUNG 850 evo SSD.
Host has 16G ram.

Mkfs parameter:
--nodesize 4K (To bump up tree size)

Initial subvolume contents:
4G data copied from /usr and /lib.
(With enough regular small files)

Snapshots:
16 snapshots of the original subvolume.
each snapshot has 3 random files modified.

balance parameter:
-m

So the content should be pretty similar to a real world root fs layout.

                     | v4.19-rc1    | w/ patchset    | diff (*)
---------------------------------------------------------------
relocated extents    | 22929        | 22900          | -0.1%
qgroup dirty extents | 227757       | 167139         | -26.6%
time (sys)           | 65.253s      | 50.123s        | -23.2%
time (real)          | 74.032s      | 52.551s        | -29.0%

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: qgroup: Use generation-aware subtree swap to mark dirty extents

Before this patch, with quota enabled during balance, we need to mark
the whole subtree dirty for quota.

E.g.
OO = Old tree blocks (from file tree)
NN = New tree blocks (from reloc tree)

        File tree (src)           Reloc tree (dst)
            OO (a)                              NN (a)
           /  \                                /  \
     (b) OO    OO (c)                    (b) NN    NN (c)
        /  \  /  \                          /  \  /  \
       OO  OO OO OO (d)                    OO  OO OO NN (d)

For old balance + quota case, quota will mark the whole src and dst tree
dirty, including all the 3 old tree blocks in reloc tree.

It's doable for small file tree or new tree blocks are all located at
lower level.

But for large file tree or new tree blocks are all located at higher
level, this will lead to mark the whole tree dirty, and be unbelievably
slow.

This patch will change how we handle such balance with quota enabled
case.

Now we will search from (b) and (c) for any new tree blocks whose
generation is equal to @last_snapshot, and only mark them dirty.

In above case, we only need to trace tree blocks NN(b), NN(c) and NN(d).
(NN(a) will be traced when COW happens for nodeptr modification).  And
also for tree blocks OO(b), OO(c), OO(d). (OO(a) will be traced when COW
happens for nodeptr modification.)

For above case, we could skip 3 tree blocks, but for larger tree, we can
skip tons of unmodified tree blocks, and hugely speed up balance.

This patch will introduce a new function,
btrfs_qgroup_trace_subtree_swap(), which will do the following main
work:

1) Read out real root eb
   And setup basic dst_path for later calls
2) Call qgroup_trace_new_subtree_blocks()
   To trace all new tree blocks in reloc tree and their counter
   parts in the file tree.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: qgroup: Introduce function to find all new tree blocks of reloc tree

Introduce new function, qgroup_trace_new_subtree_blocks(), to iterate
all new tree blocks in a reloc tree.
So that qgroup could skip unrelated tree blocks during balance, which
should hugely speedup balance speed when quota is enabled.

The function qgroup_trace_new_subtree_blocks() itself only cares about
new tree blocks in reloc tree.

All its main works are:

1) Read out tree blocks according to parent pointers

2) Do recursive depth-first search
   Will call the same function on all its children tree blocks, with
   search level set to current level -1.
   And will also skip all children whose generation is smaller than
   @last_snapshot.

3) Call qgroup_trace_extent_swap() to trace tree blocks

So although we have parameter list related to source file tree, it's not
used at all, but only passed to qgroup_trace_extent_swap().
Thus despite the tree read code, the core should be pretty short and all
about recursive depth-first search.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: qgroup: Introduce function to trace two swaped extents

Introduce a new function, qgroup_trace_extent_swap(), which will be used
later for balance qgroup speedup.

The basis idea of balance is swapping tree blocks between reloc tree and
the real file tree.

The swap will happen in highest tree block, but there may be a lot of
tree blocks involved.

For example:
OO = Old tree blocks
NN = New tree blocks allocated during balance

          File tree (257)                  Reloc tree for 257
L2              OO                                NN
              /    \                            /    \
L1          OO      OO (a)                    OO      NN (a)
           / \     / \                       / \     / \
L0       OO   OO OO   OO                   OO   OO NN   NN
                 (b)  (c)                          (b)  (c)

When calling qgroup_trace_extent_swap(), we will pass:
@src_eb = OO(a)
@dst_path = [ nodes[1] = NN(a), nodes[0] = NN(c) ]
@dst_level = 0
@root_level = 1

In that case, qgroup_trace_extent_swap() will search from OO(a) to
reach OO(c), then mark both OO(c) and NN(c) as qgroup dirty.

The main work of qgroup_trace_extent_swap() can be split into 3 parts:

1) Tree search from @src_eb
   It should acts as a simplified btrfs_search_slot().
   The key for search can be extracted from @dst_path->nodes[dst_level]
   (first key).

2) Mark the final tree blocks in @src_path and @dst_path qgroup dirty
   NOTE: In above case, OO(a) and NN(a) won't be marked qgroup dirty.
   They should be marked during preivous (@dst_level = 1) iteration.

3) Mark file extents in leaves dirty
   We don't have good way to pick out new file extents only.
   So we still follow the old method by scanning all file extents in
   the leave.

This function can free us from keeping two pathes, thus later we only need
to care about how to iterate all new tree blocks in reloc tree.

Signed-off-by: Qu Wenruo <wqu@suse.com>
[ copy changelog to function comment ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: qgroup: Introduce trace event to analyse the number of dirty extents accounted

Number of qgroup dirty extents is directly linked to the performance
overhead, so add a new trace event, trace_qgroup_num_dirty_extents(), to
record how many dirty extents is processed in
btrfs_qgroup_account_extents().

This will be pretty handy to analyze later balance performance
improvement.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: relocation: Add basic extent backref related comments for build_backref_tree

fs/btrfs/relocation.c:build_backref_tree() is some code from 2009 era,
although it works pretty fine, it's not that easy to understand.
Especially combined with the complex btrfs backref format.

This patch adds some basic comment for the backref build part of the
code, making it less hard to read, at least for backref searching part.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: get rid of btrfs_symlink_aops

The only aops we define for symlinks are identical to the aops for
regular files. This has been the case since symlink support was added in
commit 2b8d99a723a3 ("Btrfs: symlinks and hard links"). As far as I can
tell, there wasn't a good reason to have separate aops then, and there
isn't now, so let's just do what most other filesystems do and reuse the
same structure.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: don't clean dirty pages during buffered writes

During buffered writes, we follow this basic series of steps:

again:
lock all the pages
wait for writeback on all the pages
Take the extent range lock
wait for ordered extents on the whole range
clean all the pages

if (copy_from_user_in_atomic() hits a fault) {
drop our locks
goto again;
}

dirty all the pages
release all the locks

The extra waiting, cleaning and locking are there to make sure we don't
modify pages in flight to the drive, after they've been crc'd.

If some of the pages in the range were already dirty when the write
began, and we need to goto again, we create a window where a dirty page
has been cleaned and unlocked. It may be reclaimed before we're able to
lock it again, which means we'll read the old contents off the drive and
lose any modifications that had been pending writeback.

We don't actually need to clean the pages. All of the other locking in
place makes sure we don't start IO on the pages, so we can just leave
them dirty for the duration of the write.

Fixes: 73d59314e6ed (the original btrfs merge)
CC: stable@vger.kernel.org # v4.4+
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: use common helper instead of open coding a bit test

The helper does the same math and we take care about the special case
when flags is 0 too.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: refactor __btrfs_run_delayed_refs loop

Refactor the delayed refs loop by using the newly introduced
btrfs_run_delayed_refs_for_head function. This greatly simplifies
__btrfs_run_delayed_refs and makes it more obvious what is happening.

We now have 1 loop which iterates the existing delayed_heads and then
each selected ref head is processed by the new helper. All existing
semantics of the code are preserved so no functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Factor out loop processing all refs of a head

This patch introduces a new helper encompassing the implicit inner loop
in __btrfs_run_delayed_refs which processes all the refs for a given
head. The code is mostly copy/paste, the only difference is that if we
detect a newer reference then -EAGAIN is returned so that callers can
react correctly.

Also, at the end of the loop the head is relocked and
btrfs_merge_delayed_refs is run again to retain the pre-refactoring
semantics.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Factor out ref head locking code in __btrfs_run_delayed_refs

This is in preparation to refactor the giant loop in
__btrfs_run_delayed_refs. As a first step define a new function
which implements acquiring a reference to a btrfs_delayed_refs_head and
use it. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: tests: polish ifdefs around testing helper

Avoid the inline ifdefs and use two sections for self-tests enabled and
disabled.

Though there could be no ifdef and unconditional test_bit of
BTRFS_FS_STATE_DUMMY_FS_INFO, the static inline can help to optimize out
any code that would depend on conditions using btrfs_is_testing.

As this is only for the testing code, drop unlikely().

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: tests: group declarations of self-test helpers

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: tests: move testing members of struct btrfs_root to the end

The data used only for tests are better placed at the end of the
structure so that they don't change the structure layout. All new
members of btrfs_root should be placed before.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: tests: add separate stub for find_lock_delalloc_range

The helper find_lock_delalloc_range is now conditionally built static,
dpending on whether the self-tests are enabled or not. There's a macro
that is supposed to hide the export, used only once. To discourage
further use, drop it an add a public wrapper for the helper needed by
tests.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: preftree: use rb_first_cached

rb_first_cached() trades an extra pointer "leftmost" for doing the same
job as rb_first() but in O(1).

While resolving indirect refs and missing refs, it always looks for the
first rb entry in a while loop, it's helpful to use rb_first_cached
instead.

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: extent_map: use rb_first_cached

rb_first_cached() trades an extra pointer "leftmost" for doing the
same job as rb_first() but in O(1).

As evict_inode_truncate_pages() removes all extent mapping by always
looking for the first rb entry, it's helpful to use rb_first_cached
instead.

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: delayed-inode: use rb_first_cached for ins_root and del_root

rb_first_cached() trades an extra pointer "leftmost" for doing the same job as
rb_first() but in O(1).

Functions manipulating delayed_item need to get the first entry, this converts
it to use rb_first_cached().

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: delayed-refs: use rb_first_cached for ref_tree

rb_first_cached() trades an extra pointer "leftmost" for doing the same
job as rb_first() but in O(1).

Functions manipulating href->ref_tree need to get the first entry, this
converts href->ref_tree to use rb_first_cached().

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: delayed-refs: use rb_first_cached for href_root

rb_first_cached() trades an extra pointer "leftmost" for doing the same
job as rb_first() but in O(1).

Functions manipulating href_root need to get the first entry, this
converts href_root to use rb_first_cached().

This patch is first in the sequenct of similar updates to other rbtrees
and this is analysis of the expected behaviour and improvements.

There's a common pattern:

while (node = rb_first) {
        entry = rb_entry(node)
        next = rb_next(node)
        rb_erase(node)
        cleanup(entry)
}

rb_first needs to traverse the tree up to logN depth, rb_erase can
completely reshuffle the tree. With the caching we'll skip the traversal
in rb_first.  That's a cached memory access vs looped pointer
dereference trade-off that IMHO has a clear winner.

Measurements show there's not much difference in a sample tree with
10000 nodes: 4.5s / rb_first and 4.8s / rb_first_cached. Real effects of
caching and pointer chasing are unpredictable though.

Further optimzations can be done to avoid the expensive rb_erase step.
In some cases it's ok to process the nodes in any order, so the tree can
be traversed in post-order, not rebalancing the children nodes and just
calling free. Care must be taken regarding the next node.

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog from mail discussions ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: wait on caching when putting the bg cache

While testing my backport I noticed there was a panic if I ran
generic/416 generic/417 generic/418 all in a row.  This just happened to
uncover a race where we had outstanding IO after we destroy all of our
workqueues, and then we'd go to queue the endio work on those free'd
workqueues.

This is because we aren't waiting for the caching threads to be done
before freeing everything up, so to fix this make sure we wait on any
outstanding caching that's being done before we free up the block group,
so we're sure to be done with all IO by the time we get to
btrfs_stop_all_workers().  This fixes the panic I was seeing
consistently in testing.

------------[ cut here ]------------
kernel BUG at fs/btrfs/volumes.c:6112!
SMP PTI
Modules linked in:
CPU: 1 PID: 27165 Comm: kworker/u4:7 Not tainted 4.16.0-02155-g3553e54a578d-dirty #875
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
Workqueue: btrfs-cache btrfs_cache_helper
RIP: 0010:btrfs_map_bio+0x346/0x370
RSP: 0000:ffffc900061e79d0 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff880071542e00 RCX: 0000000000533000
RDX: ffff88006bb74380 RSI: 0000000000000008 RDI: ffff880078160000
RBP: 0000000000000001 R08: ffff8800781cd200 R09: 0000000000503000
R10: ffff88006cd21200 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8800781cd200 R15: ffff880071542e00
FS:  0000000000000000(0000) GS:ffff88007fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000817ffc4 CR3: 0000000078314000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btree_submit_bio_hook+0x8a/0xd0
submit_one_bio+0x5d/0x80
read_extent_buffer_pages+0x18a/0x320
btree_read_extent_buffer_pages+0xbc/0x200
? alloc_extent_buffer+0x359/0x3e0
read_tree_block+0x3d/0x60
read_block_for_search.isra.30+0x1a5/0x360
btrfs_search_slot+0x41b/0xa10
btrfs_next_old_leaf+0x212/0x470
caching_thread+0x323/0x490
normal_work_helper+0xc5/0x310
process_one_work+0x141/0x340
worker_thread+0x44/0x3c0
kthread+0xf8/0x130
? process_one_work+0x340/0x340
? kthread_bind+0x10/0x10
ret_from_fork+0x35/0x40
RIP: btrfs_map_bio+0x346/0x370 RSP: ffffc900061e79d0
---[ end trace 827eb13e50846033 ]---
Kernel panic - not syncing: Fatal exception
Kernel Offset: disabled
---[ end Kernel panic - not syncing: Fatal exception

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: keep trim from interfering with transaction commits

Commit 499f377f49f08 (btrfs: iterate over unused chunk space in FITRIM)
fixed free space trimming, but introduced latency when it was running.
This is due to it pinning the transaction using both a incremented
refcount and holding the commit root sem for the duration of a single
trim operation.

This was to ensure safety but it's unnecessary.  We already hold the the
chunk mutex so we know that the chunk we're using can't be allocated
while we're trimming it.

In order to check against chunks allocated already in this transaction,
we need to check the pending chunks list.  To to that safely without
joining the transaction (or attaching than then having to commit it) we
need to ensure that the dev root's commit root doesn't change underneath
us and the pending chunk lists stays around until we're done with it.

We can ensure the former by holding the commit root sem and the latter
by pinning the transaction.  We do this now, but the critical section
covers the trim operation itself and we don't need to do that.

This patch moves the pinning and unpinning logic into helpers and unpins
the transaction after performing the search and check for pending
chunks.

Limiting the critical section of the transaction pinning improves the
latency substantially on slower storage (e.g. image files over NFS).

Fixes: 499f377f49f08 ("btrfs: iterate over unused chunk space in FITRIM")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: don't attempt to trim devices that don't support it

We check whether any device the file system is using supports discard in
the ioctl call, but then we attempt to trim free extents on every device
regardless of whether discard is supported. Due to the way we mask off
EOPNOTSUPP, we can end up issuing the trim operations on each free range
on devices that don't support it, just wasting time.

Fixes: 499f377f49f08 ("btrfs: iterate over unused chunk space in FITRIM")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: iterate all devices during trim, instead of fs_devices::alloc_list

btrfs_trim_fs iterates over the fs_devices->alloc_list while holding the
device_list_mutex.  The problem is that ->alloc_list is protected by the
chunk mutex.  We don't want to hold the chunk mutex over the trim of the
entire file system.  Fortunately, the ->dev_list list is protected by
the dev_list mutex and while it will give us all devices, including
read-only devices, we already just skip the read-only devices.  Then we
can continue to take and release the chunk mutex while scanning each
device.

Fixes: 499f377f49f ("btrfs: iterate over unused chunk space in FITRIM")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Ensure btrfs_trim_fs can trim the whole filesystem

[BUG]
fstrim on some btrfs only trims the unallocated space, not trimming any
space in existing block groups.

[CAUSE]
Before fstrim_range passed to btrfs_trim_fs(), it gets truncated to
range [0, super->total_bytes). So later btrfs_trim_fs() will only be
able to trim block groups in range [0, super->total_bytes).

While for btrfs, any bytenr aligned to sectorsize is valid, since btrfs
uses its logical address space, there is nothing limiting the location
where we put block groups.

For filesystem with frequent balance, it's quite easy to relocate all
block groups and bytenr of block groups will start beyond
super->total_bytes.

In that case, btrfs will not trim existing block groups.

[FIX]
Just remove the truncation in btrfs_ioctl_fitrim(), so btrfs_trim_fs()
can get the unmodified range, which is normally set to [0, U64_MAX].

Reported-by: Chris Murphy <lists@colorremedies.com>
Fixes: f4c697e6406d ("btrfs: return EINVAL if start > total_bytes in fitrim ioctl")
CC: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Enhance btrfs_trim_fs function to handle error better

Function btrfs_trim_fs() doesn't handle errors in a consistent way. If
error happens when trimming existing block groups, it will skip the
remaining blocks and continue to trim unallocated space for each device.

The return value will only reflect the final error from device trimming.

This patch will fix such behavior by:

1) Recording the last error from block group or device trimming
   The return value will also reflect the last error during trimming.
   Make developer more aware of the problem.

2) Continuing trimming if possible
   If we failed to trim one block group or device, we could still try
   the next block group or device.

3) Report number of failures during block group and device trimming
   It would be less noisy, but still gives user a brief summary of
   what's going wrong.

Such behavior can avoid confusion for cases like failure to trim the
first block group and then only unallocated space is trimmed.

Reported-by: Chris Murphy <lists@colorremedies.com>
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add bg_ret and dev_ret to the messages ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix error handling in btrfs_dev_replace_start

When we fail to start a transaction in btrfs_dev_replace_start, we leave
dev_replace->replace_start set to STARTED but clear ->srcdev and
->tgtdev.  Later, that can result in an Oops in
btrfs_dev_replace_progress when having state set to STARTED or SUSPENDED
implies that ->srcdev is valid.

Also fix error handling when the state is already STARTED or SUSPENDED
while starting.  That, too, will clear ->srcdev and ->tgtdev even though
it doesn't own them.  This should be an impossible case to hit since we
should be protected by the BTRFS_FS_EXCL_OP bit being set.  Let's add an
ASSERT there while we're at it.

Fixes: e93c89c1aaaaa (Btrfs: add new sources for device replace code)
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: change remove_extent_mapping to return void

remove_extent_mapping uses the variable "ret" for return value, but it
is not modified after initialzation. Further, I find that any of the
callers do not handle the return value and the callees are only simple
functions so the return values does not need to be passed.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: handle error of get_old_root

In btrfs_search_old_slot get_old_root is always used with the assumption
it cannot fail. However, this is not true in rare circumstance it can
fail and return null. This will lead to null point dereference when the
header is read. Fix this by checking the return value and properly
handling NULL by setting ret to -EIO and returning gracefully.

Coverity-id: 1087503
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Remove logically dead code from btrfs_orphan_cleanup

In btrfs_orphan_cleanup the final 'if (ret) goto out' cannot ever be
executed. This is due to the last assignment to 'ret' depending on the
return value of btrfs_iget. If an error other than -ENOENT is returned
then the loop is prematurely terminated by 'goto out'. On the other
hand, if the error value is ENOENT then a subsequent if branch is
executed that always re-assigns 'ret' and in case it's an error just
terminates the loop. No functional changes.

Coverity-id: 1437392
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: remove wait_ordered_range in btrfs_evict_inode

When we delete an inode,

btrfs_evict_inode() {
    truncate_inode_pages_final()
        truncate_inode_pages_range()
            lock_page()
            truncate_cleanup_page()
                 btrfs_invalidatepage()
                      wait_on_page_writeback
                           btrfs_lookup_ordered_range()
                 cancel_dirty_page()
           unlock_page()
     ...
     btrfs_wait_ordered_range()
     ...

As VFS has called ->invalidatepage() to get all ordered extents done (if
there are any) and truncated all page cache pages (no dirty pages to
writeback after this step), wait_ordered_range() is just a noop.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: skip set_page_dirty if eb pages are already dirty

As long as @eb is marked with EXTENT_BUFFER_DIRTY, all of its pages
are dirty, so no need to set pages dirty again.

Ftrace showed that the loop took 10us on my dev box, so removing this
can save us at least 10us if eb is already dirty and otherwise avoid a
potentially expensive calls to set_page_dirty.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: assert page dirty bit on extent buffer pages

Just in case that someone breaks the rule that pages are dirty as long
as eb is dirty. The next patch will dirty the pages conditionally.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: remove unnecessary level check in balance_level

In the callchain:

btrfs_search_slot()
   if (level != 0)
      setup_nodes_for_search()
          balance_level()

It is just impossible to have level=0 in balance_level, we can drop the
check.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: unify error handling of btrfs_lookup_dir_item

Unify the error handling of directory item lookups using IS_ERR_OR_NULL.
No functional changes.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: use args in the correct order for kcalloc in btrfsic_read_block

kcalloc is defined as:

kcalloc(size_t n, size_t size, gfp_t flags)

Although this won't cause problems in practice, btrfsic_read_block()
uses kcalloc with n and size in the opposite order.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Make btrfs_find_device_by_devspec return btrfs_device directly

Instead of returning an error value and using one of the parameters for
returning the actual object we are interested in just refactor the
function to directly return btrfs_device *. Also bubble up the error
handling for the special BTRFS_ERROR_DEV_MISSING_NOT_FOUND value into
btrfs_rm_device. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Make btrfs_find_device_missing_or_by_path return directly a device

This function returns a numeric error value and additionally the
device found in one of its input parameters. Simplify this by making
the function directly return a pointer to btrfs_device. Additionally
adjust the caller to handle the case when we want to remove the
'missing' device and ENOENT is returned to return the expected
positive error value, parsed by progs. Finally, unexport the function
since it's not called outside of volume.c. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Make btrfs_find_device_by_path return struct btrfs_device

Currently this function returns an error code as well as uses one of
its arguments as a return value for struct btrfs_device. Change the
function so that it returns btrfs_device directly and use the usual
"encode error in pointer" mechanics if something goes wrong. No
functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: fix error handling in free_log_tree

When we hit an I/O error in free_log_tree->walk_log_tree during file system
shutdown we can crash due to there not being a valid transaction handle.

Use btrfs_handle_fs_error when there's no transaction handle to use.

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000060
  IP: free_log_tree+0xd2/0x140 [btrfs]
  PGD 0 P4D 0
  Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
  Modules linked in: <modules>
  CPU: 2 PID: 23544 Comm: umount Tainted: G        W        4.12.14-kvmsmall #9 SLE15 (unreleased)
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
  task: ffff96bfd3478880 task.stack: ffffa7cf40d78000
  RIP: 0010:free_log_tree+0xd2/0x140 [btrfs]
  RSP: 0018:ffffa7cf40d7bd10 EFLAGS: 00010282
  RAX: 00000000fffffffb RBX: 00000000fffffffb RCX: 0000000000000002
  RDX: 0000000000000000 RSI: ffff96c02f07d4c8 RDI: 0000000000000282
  RBP: ffff96c013cf1000 R08: ffff96c02f07d4c8 R09: ffff96c02f07d4d0
  R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000000
  R13: ffff96c005e800c0 R14: ffffa7cf40d7bdb8 R15: 0000000000000000
  FS:  00007f17856bcfc0(0000) GS:ffff96c03f600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000060 CR3: 0000000045ed6002 CR4: 00000000003606e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   ? wait_for_writer+0xb0/0xb0 [btrfs]
   btrfs_free_log+0x17/0x30 [btrfs]
   btrfs_drop_and_free_fs_root+0x9a/0xe0 [btrfs]
   btrfs_free_fs_roots+0xc0/0x130 [btrfs]
   ? wait_for_completion+0xf2/0x100
   close_ctree+0xea/0x2e0 [btrfs]
   ? kthread_stop+0x161/0x260
   generic_shutdown_super+0x6c/0x120
   kill_anon_super+0xe/0x20
   btrfs_kill_super+0x13/0x100 [btrfs]
   deactivate_locked_super+0x3f/0x70
   cleanup_mnt+0x3b/0x70
   task_work_run+0x78/0x90
   exit_to_usermode_loop+0x77/0xa6
   do_syscall_64+0x1c5/0x1e0
   entry_SYSCALL_64_after_hwframe+0x42/0xb7
  RIP: 0033:0x7f1784f90827
  RSP: 002b:00007ffdeeb03118 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
  RAX: 0000000000000000 RBX: 0000556a60c62970 RCX: 00007f1784f90827
  RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000556a60c62b50
  RBP: 0000000000000000 R08: 0000000000000005 R09: 00000000ffffffff
  R10: 0000556a60c63900 R11: 0000000000000246 R12: 0000556a60c62b50
  R13: 00007f17854a81c4 R14: 0000000000000000 R15: 0000000000000000
  RIP: free_log_tree+0xd2/0x140 [btrfs] RSP: ffffa7cf40d7bd10
  CR2: 0000000000000060

Fixes: 681ae50917df9 ("Btrfs: cleanup reserved space when freeing tree log on error")
CC: <stable@vger.kernel.org> # v3.13
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove redundant variable from btrfs_cross_ref_exist

Since commit d7df2c796d7e ("Btrfs attach delayed ref updates to delayed
ref heads"), check_delayed_ref() won't return -ENOENT.

In btrfs_cross_ref_exist(), two variables 'ret' and 'ret2' are
originally used to handle -ENOENT error case. Since the code is not
needed anymore, let's just remove 'ret2'.

Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: set leave_spinning in btrfs_get_extent

Unless it's going to read inline extents from btree leaf to page,
btrfs_get_extent won't sleep during the period of holding path lock.

This sets leave_spinning at first and sets path to blocking mode right
before reading inline extent if that's the case. The benefit is that a
path in spinning mode typically has lower impact (faster) on waiters
rather than that in the blocking mode.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: fix alignment in declaration and prototype of btrfs_get_extent

This fixes btrfs_get_extent to be consistent with our existing
declaration style.

Note: For the record, indentation styles that are accepted are both,
aligning under the opening ( and tab or double tab indentation on the
next line. Preferrably not spliting the type or long expressions in the
argument lists.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
[ add note ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove unused pointer 'tree' in btrfs_submit_compressed_read

Pointer 'tree' is being assigned but is never used hence it is redundant
and can be removed. This is a leftover from cleanup patch
00032d38eaa89c76de7 ("btrfs: drop extent_io_ops::merge_bio_hook
callback").

Cleans up clang warning:

warning: variable 'tree' set but not used [-Wunused-but-set-variable]

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove unused pointer inode in relink_file_extents

Pointer inode is being assigned but is never used hence it is redundant
and can be removed. It's been unused since the introduction in
38c227d87c49a ("Btrfs: snapshot-aware defrag").

Cleans up clang warning:

variable ‘inode’ set but not used [-Wunused-but-set-variable]

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: defrag: use btrfs_mod_outstanding_extents in cluster_pages_for_defrag

Since commit 8b62f87bad9c ("Btrfs: rework outstanding_extents"),
manual operations of outstanding_extent in btrfs_inode are replaced by
btrfs_mod_outstanding_extents().
The one in cluster_pages_for_defrag seems to be lost, so replace it
of btrfs_mod_outstanding_extents().

Fixes: 8b62f87bad9c ("Btrfs: rework outstanding_extents")
Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: remove confusing tracepoint in btrfs_add_reserved_bytes

Here we're not releasing any space, but transferring bytes from
->bytes_may_use to ->bytes_reserved. The last change to the code in
commit 18513091af9483ba8 ("btrfs: update btrfs_space_info's
bytes_may_use timely") removed a conditional tracepoint and the logic
changed too but the tracepiont remained.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: free path at an earlier point in btrfs_get_extent

trace_btrfs_get_extent() has nothing to do with path, place
btrfs_free_path ahead so that we can unlock path on error.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Btrfs: use next_state in find_first_extent_bit

As next_state() is already defined to get the next state, use it in
find_first_extent_bit. No functional changes.

Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: locking: Add extra check in btrfs_init_new_buffer() to avoid deadlock

[BUG]
For certain crafted image, whose csum root leaf has missing backref, if
we try to trigger write with data csum, it could cause deadlock with the
following kernel WARN_ON():

  WARNING: CPU: 1 PID: 41 at fs/btrfs/locking.c:230 btrfs_tree_lock+0x3e2/0x400
  CPU: 1 PID: 41 Comm: kworker/u4:1 Not tainted 4.18.0-rc1+ #8
  Workqueue: btrfs-endio-write btrfs_endio_write_helper
  RIP: 0010:btrfs_tree_lock+0x3e2/0x400
  Call Trace:
   btrfs_alloc_tree_block+0x39f/0x770
   __btrfs_cow_block+0x285/0x9e0
   btrfs_cow_block+0x191/0x2e0
   btrfs_search_slot+0x492/0x1160
   btrfs_lookup_csum+0xec/0x280
   btrfs_csum_file_blocks+0x2be/0xa60
   add_pending_csums+0xaf/0xf0
   btrfs_finish_ordered_io+0x74b/0xc90
   finish_ordered_fn+0x15/0x20
   normal_work_helper+0xf6/0x500
   btrfs_endio_write_helper+0x12/0x20
   process_one_work+0x302/0x770
   worker_thread+0x81/0x6d0
   kthread+0x180/0x1d0
   ret_from_fork+0x35/0x40

[CAUSE]
That crafted image has missing backref for csum tree root leaf.  And
when we try to allocate new tree block, since there is no
EXTENT/METADATA_ITEM for csum tree root, btrfs consider it's free slot
and use it.

The extent tree of the image looks like:

  Normal image                      |       This fuzzed image
  ----------------------------------+--------------------------------
  BG 29360128                       | BG 29360128
   One empty slot                   |  One empty slot
  29364224: backref to UUID tree    | 29364224: backref to UUID tree
   Two empty slots                  |  Two empty slots
  29376512: backref to CSUM tree    |  One empty slot (bad type) <<<
  29380608: backref to D_RELOC tree | 29380608: backref to D_RELOC tree
  ...                               | ...

Since bytenr 29376512 has no METADATA/EXTENT_ITEM, when btrfs try to
alloc tree block, it's an valid slot for btrfs.

And for finish_ordered_write, when we need to insert csum, we try to CoW
csum tree root.

By accident, empty slots at bytenr BG_OFFSET, BG_OFFSET + 8K,
BG_OFFSET + 12K is already used by tree block COW for other trees, the
next empty slot is BG_OFFSET + 16K, which should be the backref for CSUM
tree.

But due to the bad type, btrfs can recognize it and still consider it as
an empty slot, and will try to use it for csum tree CoW.

Then in the following call trace, we will try to lock the new tree
block, which turns out to be the old csum tree root which is already
locked:

btrfs_search_slot() called on csum tree root, which is at 29376512
|- btrfs_cow_block()
   |- btrfs_set_lock_block()
   |  |- Now locks tree block 29376512 (old csum tree root)
   |- __btrfs_cow_block()
      |- btrfs_alloc_tree_block()
         |- btrfs_reserve_extent()
            | Now it returns tree block 29376512, which extent tree
            | shows its empty slot, but it's already hold by csum tree
            |- btrfs_init_new_buffer()
               |- btrfs_tree_lock()
                  | Triggers WARN_ON(eb->lock_owner == current->pid)
                  |- wait_event()
                     Wait lock owner to release the lock, but it's
                     locked by ourself, so it will deadlock

[FIX]
This patch will do the lock_owner and current->pid check at
btrfs_init_new_buffer().
So above deadlock can be avoided.

Since such problem can only happen in crafted image, we will still
trigger kernel warning for later aborted transaction, but with a little
more meaningful warning message.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=200405
Reported-by: Xu Wen <wen.xu@gatech.edu>
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Handle owner mismatch gracefully when walking up tree

[BUG]
When mounting certain crafted image, btrfs will trigger kernel BUG_ON()
when trying to recover balance:

  kernel BUG at fs/btrfs/extent-tree.c:8956!
  invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 1 PID: 662 Comm: mount Not tainted 4.18.0-rc1-custom+ #10
  RIP: 0010:walk_up_proc+0x336/0x480 [btrfs]
  RSP: 0018:ffffb53540c9b890 EFLAGS: 00010202
  Call Trace:
   walk_up_tree+0x172/0x1f0 [btrfs]
   btrfs_drop_snapshot+0x3a4/0x830 [btrfs]
   merge_reloc_roots+0xe1/0x1d0 [btrfs]
   btrfs_recover_relocation+0x3ea/0x420 [btrfs]
   open_ctree+0x1af3/0x1dd0 [btrfs]
   btrfs_mount_root+0x66b/0x740 [btrfs]
   mount_fs+0x3b/0x16a
   vfs_kern_mount.part.9+0x54/0x140
   btrfs_mount+0x16d/0x890 [btrfs]
   mount_fs+0x3b/0x16a
   vfs_kern_mount.part.9+0x54/0x140
   do_mount+0x1fd/0xda0
   ksys_mount+0xba/0xd0
   __x64_sys_mount+0x21/0x30
   do_syscall_64+0x60/0x210
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

[CAUSE]
Extent tree corruption.  In this particular case, reloc tree root's
owner is DATA_RELOC_TREE (should be TREE_RELOC), thus its backref is
corrupted and we failed the owner check in walk_up_tree().

[FIX]
It's pretty hard to take care of every extent tree corruption, but at
least we can remove such BUG_ON() and exit more gracefully.

And since in this particular image, DATA_RELOC_TREE and TREE_RELOC share
the same root (which is obviously invalid), we needs to make
__del_reloc_root() more robust to detect such invalid sharing to avoid
possible NULL dereference as root->node can be NULL in this case.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=200411
Reported-by: Xu Wen <wen.xu@gatech.edu>
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: change btrfs_pin_log_trans to return void

btrfs_pin_log_trans defines the variable "ret" for return value, but it
is not modified after initialization. Further, I find that none of the
callers do handles the return value, so it is safe to drop the unneeded
"ret" and make it return void.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: change btrfs_free_reserved_bytes to return void

btrfs_free_reserved_bytes uses the variable "ret" for return value,
but it is not modified after initialzation. Further, I find that any of
the callers do not handle the return value, so it is safe to drop the
unneeded "ret" and return void. There are no callees that would need the
function to handle or pass the value either.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>