tree f2ff6c059e24d7fdf2e1fff498bbef0bb90bfbfc
parent 3935127c50c84106d654ef14962cff28c660bc62
author Chris Mason <chris.mason@oracle.com> 1233757465 -0500
committer Chris Mason <chris.mason@oracle.com> 1233757465 -0500

Btrfs: hash_lock is no longer needed

Before metadata is written to disk, it is updated to reflect that writeout
has begun.  Once this update is done, the block must be cow'd before it
can be modified again.

This update was originally synchronized by using a per-fs spinlock.  Today
the buffers for the metadata blocks are locked before writeout begins,
and everyone that tests the flag has the buffer locked as well.

So, the per-fs spinlock (called hash_lock for no good reason) is no
longer required.

Signed-off-by: Chris Mason <chris.mason@oracle.com>