From 5bd88d153998c1b189fdeb8b8bd4cce36b5acf62 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 21 Jun 2018 23:26:57 -0700 Subject: [PATCH] xfs: recheck reflink state after grabbing ILOCK_SHARED for a write The reflink iflag could have changed since the earlier unlocked check, so if we got ILOCK_SHARED for a write and but we're now a reflink inode we have to switch to ILOCK_EXCL and relock. This helps us avoid blowing lock assertions in things like generic/166: XFS: Assertion failed: xfs_isilocked(ip, XFS_ILOCK_EXCL), file: fs/xfs/xfs_reflink.c, line: 383 WARNING: CPU: 1 PID: 24707 at fs/xfs/xfs_message.c:104 assfail+0x25/0x30 [xfs] Modules linked in: deadline_iosched dm_snapshot dm_bufio ext4 mbcache jbd2 dm_flakey xfs libcrc32c dax_pmem device_dax nd_pmem sch_fq_codel af_packet [last unloaded: scsi_debug] CPU: 1 PID: 24707 Comm: xfs_io Not tainted 4.18.0-rc1-djw #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1ubuntu1 04/01/2014 RIP: 0010:assfail+0x25/0x30 [xfs] Code: ff 0f 0b c3 90 66 66 66 66 90 48 89 f1 41 89 d0 48 c7 c6 e8 ef 1b a0 48 89 fa 31 ff e8 54 f9 ff ff 80 3d fd ba 0f 00 00 75 03 <0f> 0b c3 0f 0b 66 0f 1f 44 00 00 66 66 66 66 90 48 63 f6 49 89 f9 RSP: 0018:ffffc90006423ad8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff880030b65e80 RCX: 0000000000000000 RDX: 00000000ffffffc0 RSI: 000000000000000a RDI: ffffffffa01b0447 RBP: ffffc90006423c10 R08: 0000000000000000 R09: 0000000000000000 R10: ffff88003d43fc30 R11: f000000000000000 R12: ffff880077cda000 R13: 0000000000000000 R14: ffffc90006423c30 R15: ffffc90006423bf9 FS: 00007feba8986800(0000) GS:ffff88003ec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000138ab58 CR3: 000000003d40a000 CR4: 00000000000006a0 Call Trace: xfs_reflink_allocate_cow+0x24c/0x3d0 [xfs] xfs_file_iomap_begin+0x6d2/0xeb0 [xfs] ? iomap_to_fiemap+0x80/0x80 iomap_apply+0x5e/0x130 iomap_dio_rw+0x2e0/0x400 ? iomap_to_fiemap+0x80/0x80 ? xfs_file_dio_aio_write+0x133/0x4a0 [xfs] xfs_file_dio_aio_write+0x133/0x4a0 [xfs] xfs_file_write_iter+0x7b/0xb0 [xfs] __vfs_write+0x16f/0x1f0 vfs_write+0xc8/0x1c0 ksys_pwrite64+0x74/0x90 do_syscall_64+0x56/0x180 entry_SYSCALL_64_after_hwframe+0x49/0xbe Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_iomap.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 49f5492eed3b..55876dd02f0c 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -963,12 +963,13 @@ xfs_ilock_for_iomap( unsigned *lockmode) { unsigned mode = XFS_ILOCK_SHARED; + bool is_write = flags & (IOMAP_WRITE | IOMAP_ZERO); /* * COW writes may allocate delalloc space or convert unwritten COW * extents, so we need to make sure to take the lock exclusively here. */ - if (xfs_is_reflink_inode(ip) && (flags & (IOMAP_WRITE | IOMAP_ZERO))) { + if (xfs_is_reflink_inode(ip) && is_write) { /* * FIXME: It could still overwrite on unshared extents and not * need allocation. @@ -989,6 +990,7 @@ xfs_ilock_for_iomap( mode = XFS_ILOCK_EXCL; } +relock: if (flags & IOMAP_NOWAIT) { if (!xfs_ilock_nowait(ip, mode)) return -EAGAIN; @@ -996,6 +998,17 @@ xfs_ilock_for_iomap( xfs_ilock(ip, mode); } + /* + * The reflink iflag could have changed since the earlier unlocked + * check, so if we got ILOCK_SHARED for a write and but we're now a + * reflink inode we have to switch to ILOCK_EXCL and relock. + */ + if (mode == XFS_ILOCK_SHARED && is_write && xfs_is_reflink_inode(ip)) { + xfs_iunlock(ip, mode); + mode = XFS_ILOCK_EXCL; + goto relock; + } + *lockmode = mode; return 0; } -- 2.34.1