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| author | Josef Bacik <jbacik@fusionio.com> | 2012-07-20 20:25:24 (GMT) |
|---|---|---|
| committer | Chris Mason <chris.mason@fusionio.com> | 2012-07-23 20:28:09 (GMT) |
| commit | 51561ffec9614618f3da362f9d1b03a95b717484 (patch) | |
| tree | 0698cb8f1e7de2217b3060866b91a5bd7faa8411 /fs | |
| parent | 594831c4b232b094d645503ecedec2e35dcebdf3 (diff) | |
| download | linux-fsl-qoriq-51561ffec9614618f3da362f9d1b03a95b717484.tar.xz | |
Btrfs: lock the transition from dirty to writeback for an eb
There is a small window where an eb can have no IO bits set on it, which
could potentially result in extent_buffer_under_io() returning false when we
want it to return true, which could result in not fun things happening. So
in order to protect this case we need to hold the refs_lock when we make
this transition to make sure we get reliable results out of
extent_buffer_udner_io(). Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/extent_io.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index e1939a6..97efc2f 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3077,8 +3077,15 @@ static int lock_extent_buffer_for_io(struct extent_buffer *eb, } } + /* + * We need to do this to prevent races in people who check if the eb is + * under IO since we can end up having no IO bits set for a short period + * of time. + */ + spin_lock(&eb->refs_lock); if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) { set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags); + spin_unlock(&eb->refs_lock); btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN); spin_lock(&fs_info->delalloc_lock); if (fs_info->dirty_metadata_bytes >= eb->len) @@ -3087,6 +3094,8 @@ static int lock_extent_buffer_for_io(struct extent_buffer *eb, WARN_ON(1); spin_unlock(&fs_info->delalloc_lock); ret = 1; + } else { + spin_unlock(&eb->refs_lock); } btrfs_tree_unlock(eb); |