linux-kernel - [PATCH AUTOSEL 4.4 5/5] fs/fat/fatent.c: add cond_resched() to fat_count_free

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Date:   Mon, 22 Oct 2018 06:22:32 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Khazhismel Kumykov <khazhy@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.4 5/5] fs/fat/fatent.c: add cond_resched() to fat_count_free_clusters()

From: Khazhismel Kumykov <khazhy@...gle.com>

[ 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@google.com
Signed-off-by: Khazhismel Kumykov <khazhy@...gle.com>
Acked-by: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/fat/fatent.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index a70e37c47a78..e3fc477728b3 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