From: Kemeng Shi <shikemeng@huaweicloud.com>

Date: Sat, 4 Mar 2023 01:21:01 +0800

Subject: [PATCH] ext4: set goal start correctly in ext4_mb_normalize_request

References: bsc#1012628

Patch-mainline: 6.3.4

Git-commit: b07ffe6927c75d99af534d685282ea188d9f71a6

[ Upstream commit b07ffe6927c75d99af534d685282ea188d9f71a6 ]

We need to set ac_g_ex to notify the goal start used in

ext4_mb_find_by_goal. Set ac_g_ex instead of ac_f_ex in

ext4_mb_normalize_request.

Besides we should assure goal start is in range [first_data_block,

blocks_count) as ext4_mb_initialize_context does.

[ Added a check to make sure size is less than ar->pright; otherwise

  we could end up passing an underflowed value of ar->pright - size to

  ext4_get_group_no_and_offset(), which will trigger a BUG_ON later on.

  - TYT ]

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>

Link: https://lore.kernel.org/r/20230303172120.3800725-2-shikemeng@huaweicloud.com

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Signed-off-by: Sasha Levin <sashal@kernel.org>

Signed-off-by: Jiri Slaby <jslaby@suse.cz>

---

 fs/ext4/mballoc.c | 16 ++++++++++------

 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c

index 2a1df157..90daeca1 100644

--- a/fs/ext4/mballoc.c

+++ b/fs/ext4/mballoc.c

@@ -4018,6 +4018,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,

 				struct ext4_allocation_request *ar)

 {

 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);

+	struct ext4_super_block *es = sbi->s_es;

 	int bsbits, max;

 	ext4_lblk_t end;

 	loff_t size, start_off;

@@ -4213,18 +4214,21 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,

 	ac->ac_g_ex.fe_len = EXT4_NUM_B2C(sbi, size);

 	/* define goal start in order to merge */

-	if (ar->pright && (ar->lright == (start + size))) {

+	if (ar->pright && (ar->lright == (start + size)) &&

+	    ar->pright >= size &&

+	    ar->pright - size >= le32_to_cpu(es->s_first_data_block)) {

 		/* merge to the right */

 		ext4_get_group_no_and_offset(ac->ac_sb, ar->pright - size,

-						&ac->ac_f_ex.fe_group,

-						&ac->ac_f_ex.fe_start);

+						&ac->ac_g_ex.fe_group,

+						&ac->ac_g_ex.fe_start);

 		ac->ac_flags |= EXT4_MB_HINT_TRY_GOAL;

 	}

-	if (ar->pleft && (ar->lleft + 1 == start)) {

+	if (ar->pleft && (ar->lleft + 1 == start) &&

+	    ar->pleft + 1 < ext4_blocks_count(es)) {

 		/* merge to the left */

 		ext4_get_group_no_and_offset(ac->ac_sb, ar->pleft + 1,

-						&ac->ac_f_ex.fe_group,

-						&ac->ac_f_ex.fe_start);

+						&ac->ac_g_ex.fe_group,

+						&ac->ac_g_ex.fe_start);

 		ac->ac_flags |= EXT4_MB_HINT_TRY_GOAL;

 	}

-- 

2.35.3