linux-ext4 - [PATCH 07/21] ext4: protect pa->pa_free in ext4_discard_allocated

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Message-Id: <20230209194825.511043-8-shikemeng@huaweicloud.com>
Date:   Fri, 10 Feb 2023 03:48:11 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 07/21] ext4: protect pa->pa_free in ext4_discard_allocated_blocks

If ext4_mb_mark_diskspace_used fails in ext4_mb_new_blocks, we may
discard pa already in list. Protect pa with pa_lock to avoid race.

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 fs/ext4/mballoc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 433337ac8da2..4e1caac74b44 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4263,8 +4263,11 @@ static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac)
 		ext4_mb_unload_buddy(&e4b);
 		return;
 	}
-	if (pa->pa_type == MB_INODE_PA)
+	if (pa->pa_type == MB_INODE_PA) {
+		spin_lock(&pa->pa_lock);
 		pa->pa_free += ac->ac_b_ex.fe_len;
+		spin_unlock(&pa->pa_lock);
+	}
 }
 
 /*
-- 
2.30.0