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Commit 4e8a3019 authored by Jan Kara's avatar Jan Kara Committed by Joel Becker
Browse files

ocfs2: Fix possible deadlock in ocfs2_global_read_dquot() 



It is not possible to get a read lock and then try to get the same write lock
in one thread as that can block on downconvert being requested by other node
leading to deadlock. So first drop the quota lock for reading and only after
that get it for writing.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
parent 2b53bc7b

fs/ocfs2/quota_global.c

+3 −1
Original line number Diff line number Diff line
@@ -421,6 +421,7 @@ int ocfs2_global_read_dquot(struct dquot *dquot) 
	OCFS2_DQUOT(dquot)->dq_originodes = dquot->dq_dqb.dqb_curinodes;

	if (!dquot->dq_off) {	/* No real quota entry? */

		/* Upgrade to exclusive lock for allocation */

		ocfs2_qinfo_unlock(info, 0);

		err = ocfs2_qinfo_lock(info, 1);

		if (err < 0)

			goto out_qlock;
@@ -435,6 +436,7 @@ int ocfs2_global_read_dquot(struct dquot *dquot) 
out_qlock:

	if (ex)

		ocfs2_qinfo_unlock(info, 1);

	else

		ocfs2_qinfo_unlock(info, 0);

out:

	if (err < 0)