diff options
| author | Josef Bacik <josef@toxicpanda.com> | 2020-08-20 11:46:03 -0400 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2020-10-07 12:12:16 +0200 |
| commit | 9631e4cc1a030aa71dea588cc9a57533b657489f (patch) | |
| tree | 79af53be50c85a8d2fa8aeb0ffb0662506d010c1 /fs/btrfs/locking.h | |
| parent | fd7ba1c1202d15ac96d7b42256550973e12686b5 (diff) | |
btrfs: introduce BTRFS_NESTING_COW for cow'ing blocks
When we COW a block we are holding a lock on the original block, and
then we lock the new COW block. Because our lockdep maps are based on
root + level, this will make lockdep complain. We need a way to
indicate a subclass for locking the COW'ed block, so plumb through our
btrfs_lock_nesting from btrfs_cow_block down to the btrfs_init_buffer,
and then introduce BTRFS_NESTING_COW to be used for cow'ing blocks.
The reason I've added all this extra infrastructure is because there
will be need of different nesting classes in follow up patches.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/locking.h')
| -rw-r--r-- | fs/btrfs/locking.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h index 5fabda8f0a80..8b47ba34fb03 100644 --- a/fs/btrfs/locking.h +++ b/fs/btrfs/locking.h @@ -25,6 +25,14 @@ enum btrfs_lock_nesting { BTRFS_NESTING_NORMAL, /* + * When we COW a block we are holding the lock on the original block, + * and since our lockdep maps are rootid+level, this confuses lockdep + * when we lock the newly allocated COW'd block. Handle this by having + * a subclass for COW'ed blocks so that lockdep doesn't complain. + */ + BTRFS_NESTING_COW, + + /* * We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so * add this in here and add a static_assert to keep us from going over * the limit. As of this writing we're limited to 8, and we're |