This fix will cause problems for regular file unlinks. If the inode is
not cleared on node 2, then both node 1 and node 2 will fail to get try
open lock and fail to clear the orphan inodes.
I am assuming the deadlock you have seen is because of quota's enabled
and fix e3a767b60fd8a9f5e133f42f4970cff77ec43173 should have avoided
this deadlock by delaying the dropping of the dquot reference. That
didn't happen ? Why else is downconvert task taking the inode lock ?
Thanks,
--Srini
On 10/19/2014 10:28 PM, Wengang Wang wrote:
There is dead lock case like this(the Dentry is a dentry to the Inode):
node 1node 2
--- --
granted inode lock
requesting dentry lock
responding to node 1 request on dentry lock,
it calls ocfs2_do_drop_dentry_lock with the
call trace:
#4 wait_for_completion
#5 __ocfs2_cluster_lock
#6 ocfs2_inode_lock_full_nested
#7 ocfs2_evict_inode
#8 evict
#9 iput
#10 ocfs2_do_drop_dentry_lock
You can see node 2 is requesting the inode lock before unlocking dentry lock
thus a two nodes dead lock formed.
The story is like this:
Responding node 1's request, Node 2, ocfs2_dentry_convert_worker, returned
UNBLOCK_STOP_POST which means don't downconvert but do post_unlock action.
It was doing so because it thought it doesn't need to downconvert but will do
an unlock instead in the post_unlock action ocfs2_dentry_post_unlock().
By doing so it can save a clusted downconvert request for performace
consideration. But in ocfs2_dentry_post_unlock() before unlock the dentry
lock,
it was requesting the inode lock forming the deadlock expectedly.
Fix:
unlock dentry lock first before the requesting inode lock in
ocfs2_do_drop_dentry_lock.
Signed-off-by: Wengang Wang wen.gang.w...@oracle.com
---
fs/ocfs2/dcache.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c
index e2e05a1..19a7d6c 100644
--- a/fs/ocfs2/dcache.c
+++ b/fs/ocfs2/dcache.c
@@ -369,9 +369,9 @@ out_attach:
static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
struct ocfs2_dentry_lock *dl)
{
- iput(dl-dl_inode);
ocfs2_simple_drop_lockres(osb, dl-dl_lockres);
ocfs2_lock_res_free(dl-dl_lockres);
+ iput(dl-dl_inode);
kfree(dl);
}
___
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