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| author | Filipe Manana <fdmanana@suse.com> | 2021-02-05 12:55:36 +0000 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2021-02-22 17:15:55 +0100 |
| commit | 20903032cd9f0260b99aeab92e6540f0350e4a23 (patch) | |
| tree | f397f1d78b7af75ea2f44d536faa1591e3c5a19e /fs/btrfs | |
| parent | 3c17916510428dbccdf657de050c34e208347089 (diff) | |
| download | linux-20903032cd9f0260b99aeab92e6540f0350e4a23.tar.bz2 | |
btrfs: avoid checking for RO block group twice during nocow writeback
During the nocow writeback path, we currently iterate the rbtree of block
groups twice: once for checking if the target block group is RO with the
call to btrfs_extent_readonly()), and once again for getting a nocow
reference on the block group with a call to btrfs_inc_nocow_writers().
Since btrfs_inc_nocow_writers() already returns false when the target
block group is RO, remove the call to btrfs_extent_readonly(). Not only
we avoid searching the blocks group rbtree twice, it also helps reduce
contention on the lock that protects it (specially since it is a spin
lock and not a read-write lock). That may make a noticeable difference
on very large filesystems, with thousands of allocated block groups.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/inode.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 535abf898225..d6f0e1ad3711 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1674,9 +1674,6 @@ next_slot: */ btrfs_release_path(path); - /* If extent is RO, we must COW it */ - if (btrfs_extent_readonly(fs_info, disk_bytenr)) - goto out_check; ret = btrfs_cross_ref_exist(root, ino, found_key.offset - extent_offset, disk_bytenr, false); @@ -1723,6 +1720,7 @@ next_slot: WARN_ON_ONCE(freespace_inode); goto out_check; } + /* If the extent's block group is RO, we must COW */ if (!btrfs_inc_nocow_writers(fs_info, disk_bytenr)) goto out_check; nocow = true; |