Commit e4644c5d authored by Chuck Lever's avatar Chuck Lever Committed by Zheng Zengkai
Browse files

NFSD: Fix possible sleep during nfsd4_release_lockowner() 

stable inclusion
from stable-v5.10.120
commit 3097f38e91266c7132c3fdb7e778fac858c00670
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6BR

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3097f38e91266c7132c3fdb7e778fac858c00670



--------------------------------

commit ce3c4ad7 upstream.

nfsd4_release_lockowner() holds clp->cl_lock when it calls
check_for_locks(). However, check_for_locks() calls nfsd_file_get()
/ nfsd_file_put() to access the backing inode's flc_posix list, and
nfsd_file_put() can sleep if the inode was recently removed.

Let's instead rely on the stateowner's reference count to gate
whether the release is permitted. This should be a reliable
indication of locks-in-use since file lock operations and
->lm_get_owner take appropriate references, which are released
appropriately when file locks are removed.

Reported-by: default avatarDai Ngo <dai.ngo@oracle.com>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
parent 53de5efc

fs/nfsd/nfs4state.c

+4 −8
Original line number Diff line number Diff line
@@ -7122,16 +7122,12 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp, 
		if (sop->so_is_open_owner || !same_owner_str(sop, owner))

			continue;



		/* see if there are still any locks associated with it */

		lo = lockowner(sop);

		list_for_each_entry(stp, &sop->so_stateids, st_perstateowner) {

			if (check_for_locks(stp->st_stid.sc_file, lo)) {

				status = nfserr_locks_held;

		if (atomic_read(&sop->so_count) != 1) {

			spin_unlock(&clp->cl_lock);

				return status;

			}

			return nfserr_locks_held;

		}



		lo = lockowner(sop);

		nfs4_get_stateowner(sop);

		break;

	}