Btrfs: change reserved_extents to an atomic_t
We track delayed allocation per inodes via 2 counters, one is
outstanding_extents and reserved_extents. Outstanding_extents is already an
atomic_t, but reserved_extents is not and is protected by a spinlock. So
convert this to an atomic_t and instead of using a spinlock, use atomic_cmpxchg
when releasing delalloc bytes. This makes our inode 72 bytes smaller, and
reduces locking overhead (albiet it was minimal to begin with). Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index ccc991c..57c3bb2 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -136,9 +136,8 @@
* items we think we'll end up using, and reserved_extents is the number
* of extent items we've reserved metadata for.
*/
- spinlock_t accounting_lock;
atomic_t outstanding_extents;
- int reserved_extents;
+ atomic_t reserved_extents;
/*
* ordered_data_close is set by truncate when a file that used