The patch titled
Subject: ocfs2: do not lock/unlock() inode DLM lock
has been added to the -mm tree. Its filename is
ocfs2-do-not-lock-unlock-inode-dlm-lock.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ocfs2-do-not-lock-unlock-inode-dlm-lock.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-do-not-lock-unlock-inode-dlm-lock.patch
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------------------------------------------------------
From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Subject: ocfs2: do not lock/unlock() inode DLM lock
DLM does not cache locks. So, blocking lock and unlock will only make the
performance worse where contention over the locks is high.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Joseph Qi <joseph.qi@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/dlmglue.c | 8 --------
1 file changed, 8 deletions(-)
diff -puN fs/ocfs2/dlmglue.c~ocfs2-do-not-lock-unlock-inode-dlm-lock fs/ocfs2/dlmglue.c
--- a/fs/ocfs2/dlmglue.c~ocfs2-do-not-lock-unlock-inode-dlm-lock
+++ a/fs/ocfs2/dlmglue.c
@@ -2438,12 +2438,6 @@ bail:
* done this we have to return AOP_TRUNCATED_PAGE so the aop method
* that called us can bubble that back up into the VFS who will then
* immediately retry the aop call.
- *
- * We do a blocking lock and immediate unlock before returning, though, so that
- * the lock has a great chance of being cached on this node by the time the VFS
- * calls back to retry the aop. This has a potential to livelock as nodes
- * ping locks back and forth, but that's a risk we're willing to take to avoid
- * the lock inversion simply.
*/
int ocfs2_inode_lock_with_page(struct inode *inode,
struct buffer_head **ret_bh,
@@ -2455,8 +2449,6 @@ int ocfs2_inode_lock_with_page(struct in
ret = ocfs2_inode_lock_full(inode, ret_bh, ex, OCFS2_LOCK_NONBLOCK);
if (ret == -EAGAIN) {
unlock_page(page);
- if (ocfs2_inode_lock(inode, ret_bh, ex) == 0)
- ocfs2_inode_unlock(inode, ex);
ret = AOP_TRUNCATED_PAGE;
}
_
Patches currently in -mm which might be from rgoldwyn@xxxxxxxx are
ocfs2-do-not-lock-unlock-inode-dlm-lock.patch
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