Messages in this thread Patch in this message | | | Date | Fri, 13 Feb 2009 17:12:51 -0800 | From | Greg KH <> | Subject | [patch 15/48] lockd: fix regression in lockds handling of blocked locks |
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2.6.28-stable review patch. If anyone has any objections, please let us know.
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From: J. Bruce Fields <bfields@citi.umich.edu>
commit 9d9b87c1218be78ddecbc85ec3bb91c79c1d56ab upstream.
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 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@frankvm.com> Reported-by: Frank van Maarseveen <frankvm@frankvm.com> Cc: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/lockd/svclock.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -427,7 +427,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, stru 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, stru goto out; } + ret = nlm_lck_denied; + if (!wait) + goto out; + ret = nlm_lck_blocked; /* Append to list of blocked */
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