btrfs: zoned: extend zoned allocator to use dedicated tree-log block group

This is the 1/3 patch to enable tree log on zoned filesystems.

The tree-log feature does not work on a zoned filesystem as is. Blocks for
a tree-log tree are allocated mixed with other metadata blocks and btrfs
writes and syncs the tree-log blocks to devices at the time of fsync(),
which has a different timing than a global transaction commit. As a
result, both writing tree-log blocks and writing other metadata blocks
become non-sequential writes that zoned filesystems must avoid.

Introduce a dedicated block group for tree-log blocks, so that tree-log
blocks and other metadata blocks can be separate write streams.  As a
result, each write stream can now be written to devices separately.
"fs_info->treelog_bg" tracks the dedicated block group and assigns
"treelog_bg" on-demand on tree-log block allocation time.

This commit extends the zoned block allocator to use the block group.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index f5e9f56..5064be5 100644 (file)
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -901,6 +901,8 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
        btrfs_return_cluster_to_free_space(block_group, cluster);
        spin_unlock(&cluster->refill_lock);
 
+       btrfs_clear_treelog_bg(block_group);
+
        path = btrfs_alloc_path();
        if (!path) {
                ret = -ENOMEM;

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1bb4f76..6f4b493 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -976,6 +976,8 @@ struct btrfs_fs_info {
        /* Max size to emit ZONE_APPEND write command */
        u64 max_zone_append_size;
        struct mutex zoned_meta_io_lock;
+       spinlock_t treelog_bg_lock;
+       u64 treelog_bg;
 
 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
        spinlock_t ref_verify_lock;

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d2fa925..84c6650 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2787,6 +2787,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
        spin_lock_init(&fs_info->super_lock);
        spin_lock_init(&fs_info->buffer_lock);
        spin_lock_init(&fs_info->unused_bgs_lock);
+       spin_lock_init(&fs_info->treelog_bg_lock);
        rwlock_init(&fs_info->tree_mod_log_lock);
        mutex_init(&fs_info->unused_bg_unpin_mutex);
        mutex_init(&fs_info->delete_unused_bgs_mutex);

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index cd308bf..78ad31a 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3497,6 +3497,9 @@ struct find_free_extent_ctl {
        bool have_caching_bg;
        bool orig_have_caching_bg;
 
+       /* Allocation is called for tree-log */
+       bool for_treelog;
+
        /* RAID index, converted from flags */
        int index;
 
@@ -3726,6 +3729,22 @@ static int do_allocation_clustered(struct btrfs_block_group *block_group,
 }
 
 /*
+ * Tree-log block group locking
+ * ============================
+ *
+ * fs_info::treelog_bg_lock protects the fs_info::treelog_bg which
+ * indicates the starting address of a block group, which is reserved only
+ * for tree-log metadata.
+ *
+ * Lock nesting
+ * ============
+ *
+ * space_info::lock
+ *   block_group::lock
+ *     fs_info::treelog_bg_lock
+ */
+
+/*
  * Simple allocator for sequential-only block group. It only allows sequential
  * allocation. No need to play with trees. This function also reserves the
  * bytes as in btrfs_add_reserved_bytes.
@@ -3734,23 +3753,54 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group,
                               struct find_free_extent_ctl *ffe_ctl,
                               struct btrfs_block_group **bg_ret)
 {
+       struct btrfs_fs_info *fs_info = block_group->fs_info;
        struct btrfs_space_info *space_info = block_group->space_info;
        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
        u64 start = block_group->start;
        u64 num_bytes = ffe_ctl->num_bytes;
        u64 avail;
+       u64 bytenr = block_group->start;
+       u64 log_bytenr;
        int ret = 0;
+       bool skip;
 
        ASSERT(btrfs_is_zoned(block_group->fs_info));
 
+       /*
+        * Do not allow non-tree-log blocks in the dedicated tree-log block
+        * group, and vice versa.
+        */
+       spin_lock(&fs_info->treelog_bg_lock);
+       log_bytenr = fs_info->treelog_bg;
+       skip = log_bytenr && ((ffe_ctl->for_treelog && bytenr != log_bytenr) ||
+                             (!ffe_ctl->for_treelog && bytenr == log_bytenr));
+       spin_unlock(&fs_info->treelog_bg_lock);
+       if (skip)
+               return 1;
+
        spin_lock(&space_info->lock);
        spin_lock(&block_group->lock);
+       spin_lock(&fs_info->treelog_bg_lock);
+
+       ASSERT(!ffe_ctl->for_treelog ||
+              block_group->start == fs_info->treelog_bg ||
+              fs_info->treelog_bg == 0);
 
        if (block_group->ro) {
                ret = 1;
                goto out;
        }
 
+       /*
+        * Do not allow currently using block group to be tree-log dedicated
+        * block group.
+        */
+       if (ffe_ctl->for_treelog && !fs_info->treelog_bg &&
+           (block_group->used || block_group->reserved)) {
+               ret = 1;
+               goto out;
+       }
+
        avail = block_group->length - block_group->alloc_offset;
        if (avail < num_bytes) {
                if (ffe_ctl->max_extent_size < avail) {
@@ -3765,6 +3815,9 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group,
                goto out;
        }
 
+       if (ffe_ctl->for_treelog && !fs_info->treelog_bg)
+               fs_info->treelog_bg = block_group->start;
+
        ffe_ctl->found_offset = start + block_group->alloc_offset;
        block_group->alloc_offset += num_bytes;
        spin_lock(&ctl->tree_lock);
@@ -3779,6 +3832,9 @@ static int do_allocation_zoned(struct btrfs_block_group *block_group,
        ffe_ctl->search_start = ffe_ctl->found_offset;
 
 out:
+       if (ret && ffe_ctl->for_treelog)
+               fs_info->treelog_bg = 0;
+       spin_unlock(&fs_info->treelog_bg_lock);
        spin_unlock(&block_group->lock);
        spin_unlock(&space_info->lock);
        return ret;
@@ -4028,7 +4084,12 @@ static int prepare_allocation(struct btrfs_fs_info *fs_info,
                return prepare_allocation_clustered(fs_info, ffe_ctl,
                                                    space_info, ins);
        case BTRFS_EXTENT_ALLOC_ZONED:
-               /* Nothing to do */
+               if (ffe_ctl->for_treelog) {
+                       spin_lock(&fs_info->treelog_bg_lock);
+                       if (fs_info->treelog_bg)
+                               ffe_ctl->hint_byte = fs_info->treelog_bg;
+                       spin_unlock(&fs_info->treelog_bg_lock);
+               }
                return 0;
        default:
                BUG();
@@ -4072,6 +4133,7 @@ static noinline int find_free_extent(struct btrfs_root *root,
        struct find_free_extent_ctl ffe_ctl = {0};
        struct btrfs_space_info *space_info;
        bool full_search = false;
+       bool for_treelog = (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
 
        WARN_ON(num_bytes < fs_info->sectorsize);
 
@@ -4085,6 +4147,7 @@ static noinline int find_free_extent(struct btrfs_root *root,
        ffe_ctl.orig_have_caching_bg = false;
        ffe_ctl.found_offset = 0;
        ffe_ctl.hint_byte = hint_byte_orig;
+       ffe_ctl.for_treelog = for_treelog;
        ffe_ctl.policy = BTRFS_EXTENT_ALLOC_CLUSTERED;
 
        /* For clustered allocation */
@@ -4159,8 +4222,11 @@ search:
                struct btrfs_block_group *bg_ret;
 
                /* If the block group is read-only, we can skip it entirely. */
-               if (unlikely(block_group->ro))
+               if (unlikely(block_group->ro)) {
+                       if (for_treelog)
+                               btrfs_clear_treelog_bg(block_group);
                        continue;
+               }
 
                btrfs_grab_block_group(block_group, delalloc);
                ffe_ctl.search_start = block_group->start;
@@ -4346,6 +4412,7 @@ int btrfs_reserve_extent(struct btrfs_root *root, u64 ram_bytes,
        bool final_tried = num_bytes == min_alloc_size;
        u64 flags;
        int ret;
+       bool for_treelog = (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
 
        flags = get_alloc_profile_by_root(root, is_data);
 again:
@@ -4369,8 +4436,8 @@ again:
 
                        sinfo = btrfs_find_space_info(fs_info, flags);
                        btrfs_err(fs_info,
-                                 "allocation failed flags %llu, wanted %llu",
-                                 flags, num_bytes);
+                       "allocation failed flags %llu, wanted %llu tree-log %d",
+                                 flags, num_bytes, for_treelog);
                        if (sinfo)
                                btrfs_dump_space_info(fs_info, sinfo,
                                                      num_bytes, 1);

diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index 932ad9b..61e9696 100644 (file)
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h
@@ -7,6 +7,7 @@
 #include <linux/blkdev.h>
 #include "volumes.h"
 #include "disk-io.h"
+#include "block-group.h"
 
 struct btrfs_zoned_device_info {
        /*
@@ -290,4 +291,17 @@ static inline void btrfs_zoned_meta_io_unlock(struct btrfs_fs_info *fs_info)
        mutex_unlock(&fs_info->zoned_meta_io_lock);
 }
 
+static inline void btrfs_clear_treelog_bg(struct btrfs_block_group *bg)
+{
+       struct btrfs_fs_info *fs_info = bg->fs_info;
+
+       if (!btrfs_is_zoned(fs_info))
+               return;
+
+       spin_lock(&fs_info->treelog_bg_lock);
+       if (fs_info->treelog_bg == bg->start)
+               fs_info->treelog_bg = 0;
+       spin_unlock(&fs_info->treelog_bg_lock);
+}
+
 #endif