From: Xin Yin <yinxin.x@bytedance.com>
Date: Mon, 10 Jan 2022 03:51:41 +0000 (+0800)
Subject: ext4: modify the logic of ext4_mb_new_blocks_simple
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=31a074a0c62dc0d2bfb9b543142db4fe27f9e5eb;p=linux.git

ext4: modify the logic of ext4_mb_new_blocks_simple

For now in ext4_mb_new_blocks_simple, if we found a block which
should be excluded then will switch to next group, this may
probably cause 'group' run out of range.

Change to check next block in the same group when get a block should
be excluded. Also change the search range to EXT4_CLUSTERS_PER_GROUP
and add error checking.

Signed-off-by: Xin Yin <yinxin.x@bytedance.com>
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20220110035141.1980-3-yinxin.x@bytedance.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
---

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index cf2fd9fc7d986..c781974df9d0f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5753,7 +5753,8 @@ static ext4_fsblk_t ext4_mb_new_blocks_simple(handle_t *handle,
 	struct super_block *sb = ar->inode->i_sb;
 	ext4_group_t group;
 	ext4_grpblk_t blkoff;
-	int i = sb->s_blocksize;
+	ext4_grpblk_t max = EXT4_CLUSTERS_PER_GROUP(sb);
+	ext4_grpblk_t i = 0;
 	ext4_fsblk_t goal, block;
 	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 
@@ -5775,19 +5776,26 @@ static ext4_fsblk_t ext4_mb_new_blocks_simple(handle_t *handle,
 		ext4_get_group_no_and_offset(sb,
 			max(ext4_group_first_block_no(sb, group), goal),
 			NULL, &blkoff);
-		i = mb_find_next_zero_bit(bitmap_bh->b_data, sb->s_blocksize,
+		while (1) {
+			i = mb_find_next_zero_bit(bitmap_bh->b_data, max,
 						blkoff);
+			if (i >= max)
+				break;
+			if (ext4_fc_replay_check_excluded(sb,
+				ext4_group_first_block_no(sb, group) + i)) {
+				blkoff = i + 1;
+			} else
+				break;
+		}
 		brelse(bitmap_bh);
-		if (i >= sb->s_blocksize)
-			continue;
-		if (ext4_fc_replay_check_excluded(sb,
-			ext4_group_first_block_no(sb, group) + i))
-			continue;
-		break;
+		if (i < max)
+			break;
 	}
 
-	if (group >= ext4_get_groups_count(sb) && i >= sb->s_blocksize)
+	if (group >= ext4_get_groups_count(sb) || i >= max) {
+		*errp = -ENOSPC;
 		return 0;
+	}
 
 	block = ext4_group_first_block_no(sb, group) + i;
 	ext4_mb_mark_bb(sb, block, 1, 1);