Commit 90d2f1da authored Jan 06, 2020 by Trond Myklebust Committed by J. Bruce Fields Jan 22, 2020

nfsd: Fix a soft lockup race in nfsd_file_mark_find_or_create()



If nfsd_file_mark_find_or_create() keeps winning the race for the
nfsd_file_fsnotify_group->mark_mutex against nfsd_file_mark_put()
then it can soft lock up, since fsnotify_add_inode_mark() ends
up always finding an existing entry.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

parent b6669305

fs/nfsd/filecache.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -132,9 +132,13 @@ nfsd_file_mark_find_or_create(struct nfsd_file *nf)
		struct nfsd_file_mark,
		nfm_mark));
		mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
		if (nfm) {
		fsnotify_put_mark(mark);
		if (likely(nfm))
		break;
		}
		/* Avoid soft lockup race with nfsd_file_mark_put() */
		fsnotify_destroy_mark(mark, nfsd_file_fsnotify_group);
		fsnotify_put_mark(mark);
		} else
		mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);

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