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kill-the-bkl/reiserfs: conditionaly release the write lock on fs_changed()

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The goal of fs_changed() is to check whether the tree changed during a
schedule(). This is a BKL legacy.

A recent patch added an explicit unconditional release/reacquire of the
write lock around the cond_resched() called inside fs_changed.

But it's wasteful to unconditionally do that, we are creating superfluous
lock contention in !TIF_NEED_RESCHED case.

This patch manage that by calling reiserfs_cond_resched() from fs_changed()
which only releases the lock if we are going to reschedule.

[ Impact: inject less lock contention and tree job retries ]

Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Frederic Weisbecker 2009-05-07 23:25:29 +02:00
parent e43d3f21c5
commit d663af807d
1 changed files with 1 additions and 3 deletions
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4
include/linux/reiserfs_fs.h
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@ -1348,9 +1348,7 @@ static inline loff_t max_reiserfs_offset(struct inode *inode)
#define __fs_changed(gen,s) (gen != get_generation (s))
#define fs_changed(gen,s) \
({ \
reiserfs_write_unlock(s); \
cond_resched(); \
reiserfs_write_lock(s); \
reiserfs_cond_resched(s); \
__fs_changed(gen, s); \
})