linux-kernel - [PATCH] ext4: fix trim range leak

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Message-Id: <20220614044647.21846-1-hanjinke.666@bytedance.com>
Date:   Tue, 14 Jun 2022 12:46:47 +0800
From:   Jinke Han <hanjinke.666@...edance.com>
To:     tytso@....edu, adilger.kernel@...ger.ca
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        hanjinke.666@...edance.com
Subject: [PATCH] ext4: fix trim range leak

From: hanjinke <hanjinke.666@...edance.com>

When release group lock, a large number of blocks may be alloc from
the group(e.g. not from the rest of target trim range). This may
lead end of the loop and leave the rest of trim range unprocessed.

Signed-off-by: hanjinke <hanjinke.666@...edance.com>
---
 fs/ext4/mballoc.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 9f12f29bc346..45eb9ee20947 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -6345,14 +6345,13 @@ static int ext4_try_to_trim_range(struct super_block *sb,
 __acquires(ext4_group_lock_ptr(sb, e4b->bd_group))
 __releases(ext4_group_lock_ptr(sb, e4b->bd_group))
 {
-	ext4_grpblk_t next, count, free_count;
+	ext4_grpblk_t next, count;
 	void *bitmap;
 
 	bitmap = e4b->bd_bitmap;
 	start = (e4b->bd_info->bb_first_free > start) ?
 		e4b->bd_info->bb_first_free : start;
 	count = 0;
-	free_count = 0;
 
 	while (start <= max) {
 		start = mb_find_next_zero_bit(bitmap, max + 1, start);
@@ -6367,7 +6366,6 @@ __releases(ext4_group_lock_ptr(sb, e4b->bd_group))
 				break;
 			count += next - start;
 		}
-		free_count += next - start;
 		start = next + 1;
 
 		if (fatal_signal_pending(current)) {
@@ -6381,8 +6379,6 @@ __releases(ext4_group_lock_ptr(sb, e4b->bd_group))
 			ext4_lock_group(sb, e4b->bd_group);
 		}
 
-		if ((e4b->bd_info->bb_free - free_count) < minblocks)
-			break;
 	}
 
 	return count;
-- 
2.20.1