Commit 1dbd449c authored Jan 30, 2019 by Waiman Long Committed by Linus Torvalds Jan 30, 2019

fs/dcache: Fix incorrect nr_dentry_unused accounting in shrink_dcache_sb()



The nr_dentry_unused per-cpu counter tracks dentries in both the LRU
lists and the shrink lists where the DCACHE_LRU_LIST bit is set.

The shrink_dcache_sb() function moves dentries from the LRU list to a
shrink list and subtracts the dentry count from nr_dentry_unused.  This
is incorrect as the nr_dentry_unused count will also be decremented in
shrink_dentry_list() via d_shrink_del().

To fix this double decrement, the decrement in the shrink_dcache_sb()
function is taken out.

Fixes: 4e717f5c ("list_lru: remove special case function list_lru_dispose_all."
Cc: stable@kernel.org
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 1c0490ce

fs/dcache.c

+1 −5

Original line number	Diff line number	Diff line
		@@ -1188,15 +1188,11 @@ static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
		*/
		void shrink_dcache_sb(struct super_block *sb)
		{
		long freed;

		do {
		LIST_HEAD(dispose);

		freed = list_lru_walk(&sb->s_dentry_lru,
		list_lru_walk(&sb->s_dentry_lru,
		dentry_lru_isolate_shrink, &dispose, 1024);

		this_cpu_sub(nr_dentry_unused, freed);
		shrink_dentry_list(&dispose);
		} while (list_lru_count(&sb->s_dentry_lru) > 0);
		}

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