linux-ext4 - [PATCH v2] ext2: don't set *count in the case of failure in ext2_try_to

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Message-ID: <20191026090721.23794-1-cgxu519@mykernel.net>
Date:   Sat, 26 Oct 2019 17:07:21 +0800
From:   Chengguang Xu <cgxu519@...ernel.net>
To:     jack@...e.com
Cc:     linux-ext4@...r.kernel.org, Chengguang Xu <cgxu519@...ernel.net>
Subject: [PATCH v2] ext2: don't set *count in the case of failure in ext2_try_to_allocate()

Currently we set *count to num(value 0) in the failure
of block allocation in ext2_try_to_allocate(). Without
reservation, we reuse *count(value 0) to retry block
allocation and wrong *count will cause only allocating
maximum 1 block even though having sufficent free blocks
in that block group. Finally, it probably cause significant
fragmentation.

Signed-off-by: Chengguang Xu <cgxu519@...ernel.net>
---
v1->v2:
- Add detail explanation of effect to changelog.

 fs/ext2/balloc.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index e0cc55164505..29fc3a5054f8 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -736,7 +736,6 @@ ext2_try_to_allocate(struct super_block *sb, int group,
 	*count = num;
 	return grp_goal - num;
 fail_access:
-	*count = num;
 	return -1;
 }

-- 
2.21.0