[PATCH 4.9 130/171] fs/fat/fatent.c: add cond_resched() to fat_count_free_clusters()

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

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

[ Upstream commit ac081c3be3fae6d0cc3e1862507fca3862d30b67 ]

On non-preempt kernels this loop can take a long time (more than 50 ticks)
processing through entries.

Link: http://lkml.kernel.org/r/20181010172623.57033-1-khazhy@xxxxxxxxxx
Signed-off-by: Khazhismel Kumykov <khazhy@xxxxxxxxxx>
Acked-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/fat/fatent.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index 3b7644e43796..a9cad9b60790 100644
--- a/fs/fat/fatent.c
+++ b/fs/fat/fatent.c
@@ -681,6 +681,7 @@ int fat_count_free_clusters(struct super_block *sb)
 			if (ops->ent_get(&fatent) == FAT_ENT_FREE)
 				free++;
 		} while (fat_ent_next(sbi, &fatent));
+		cond_resched();
 	}
 	sbi->free_clusters = free;
 	sbi->free_clus_valid = 1;
-- 
2.17.1