On Fri, Feb 06, 2009 at 12:29:58PM +0100, Miklos Szeredi wrote:
> On Thu, 2009-02-05 at 14:52 -0500, J. Bruce Fields wrote:
> > On Thu, Feb 05, 2009 at 11:47:09AM +0100, Miklos Szeredi wrote:
> > > But I think at least a comment in the code would be in order, or this
> > > same mistake might be made again. Also I think the original code flow
> > > is somewhat illogical.
> >
> > Yeah, I was literally just reverting the problematic lines of your
> > previous commit. I'd rather keep it that way for now, just as a clear
> > separation between the revert/bugfix and the cleanup.
>
> OK.
>
> > > How about this (it's essentially the same patch just a bit rearranged,
> > > the authorship is still yours of course ;)
> >
> > ... but would happily queue up the cleanup for 2.6.30.
>
> Cool.
>
> > Actually, I find it strange to have just that single case which breaks,
> > so that the code after the switch, which looks like it should be shared,
> > actually just applies to one case. I'd be inclined to just suck
> > everything up to "out:" into the -EAGAIN case and then make all cases
> > "goto out" (or, equivalently, break).
>
> Yes, but it needs to be sucked into the FILE_LOCK_DEFERRED case as well.
> It's just two lines and one of them is setting the error value, so it's
> not real duplication.
Whoops, right, missed that; so, I'm applying the below, sending the
fixup in now, and queuing up the cleanup for 2.6.30 (with the blame
assigned back to you, hah--object or have me add your signed-off-by).
--b.
commit c4a06d0957ea5b386b1cd83fa9a9d6c19b736346
Author: Miklos Szeredi <mszeredi@xxxxxxx>
Date: Mon Feb 9 12:30:43 2009 -0500
lockd: clean up blocking lock cases of nlsmvc_lock()
No change in behavior, just rearranging the switch so that we break out
of the switch if and only if we're in the wait case.
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 763b78a..83ee342 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -426,8 +426,15 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
ret = nlm_granted;
goto out;
case -EAGAIN:
+ /*
+ * If this is a blocking request for an
+ * already pending lock request then we need
+ * to put it back on lockd's block list
+ */
+ if (wait)
+ break;
ret = nlm_lck_denied;
- break;
+ goto out;
case FILE_LOCK_DEFERRED:
if (wait)
break;
@@ -443,10 +450,6 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
goto out;
}
- ret = nlm_lck_denied;
- if (!wait)
- goto out;
-
ret = nlm_lck_blocked;
/* Append to list of blocked */
commit 716cb6d7901f92bdfe1c80dbf4765027dceab384
Author: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
Date: Wed Feb 4 17:35:38 2009 -0500
lockd: fix regression in lockd's handling of blocked locks
If a client requests a blocking lock, is denied, then requests it again,
then here in nlmsvc_lock() we will call vfs_lock_file() without FL_SLEEP
set, because we've already queued a block and don't need the locks code
to do it again.
But that means vfs_lock_file() will return -EAGAIN instead of
FILE_LOCK_DENIED. So we still need to translate that -EAGAIN return
into a nlm_lck_blocked error in this case, and put ourselves back on
lockd's block list.
The bug was introduced by bde74e4bc64415b1 "locks: add special return
value for asynchronous locks".
Thanks to From: Frank van Maarseveen for the report; his original test
case was essentially
for i in `seq 30`; do flock /nfsmount/foo sleep 10 & done
Tested-by: Frank van Maarseveen <frankvm@xxxxxxxxxxx>
Reported-by: Frank van Maarseveen <frankvm@xxxxxxxxxxx>
Cc: Miklos Szeredi <mszeredi@xxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 6063a8e..763b78a 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -427,7 +427,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
goto out;
case -EAGAIN:
ret = nlm_lck_denied;
- goto out;
+ break;
case FILE_LOCK_DEFERRED:
if (wait)
break;
@@ -443,6 +443,10 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
goto out;
}
+ ret = nlm_lck_denied;
+ if (!wait)
+ goto out;
+
ret = nlm_lck_blocked;
/* Append to list of blocked */
--
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