linux-kernel - [PATCH AUTOSEL 4.9 4/6] ext2: fix sleeping in atomic bugs on error

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Message-Id: <20210928055734.173182-4-sashal@kernel.org>
Date:   Tue, 28 Sep 2021 01:57:32 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Dan Carpenter <dan.carpenter@...cle.com>, Jan Kara <jack@...e.cz>,
        Sasha Levin <sashal@...nel.org>, jack@...e.com,
        linux-ext4@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 4/6] ext2: fix sleeping in atomic bugs on error

From: Dan Carpenter <dan.carpenter@...cle.com>

[ Upstream commit 372d1f3e1bfede719864d0d1fbf3146b1e638c88 ]

The ext2_error() function syncs the filesystem so it sleeps.  The caller
is holding a spinlock so it's not allowed to sleep.

   ext2_statfs() <- disables preempt
   -> ext2_count_free_blocks()
      -> ext2_get_group_desc()

Fix this by using WARN() to print an error message and a stack trace
instead of using ext2_error().

Link: https://lore.kernel.org/r/20210921203233.GA16529@kili
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ext2/balloc.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index 4c40c0786e16..bd32140bdfee 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -46,10 +46,9 @@ struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
 	struct ext2_sb_info *sbi = EXT2_SB(sb);
 
 	if (block_group >= sbi->s_groups_count) {
-		ext2_error (sb, "ext2_get_group_desc",
-			    "block_group >= groups_count - "
-			    "block_group = %d, groups_count = %lu",
-			    block_group, sbi->s_groups_count);
+		WARN(1, "block_group >= groups_count - "
+		     "block_group = %d, groups_count = %lu",
+		     block_group, sbi->s_groups_count);
 
 		return NULL;
 	}
@@ -57,10 +56,9 @@ struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
 	group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
 	offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
 	if (!sbi->s_group_desc[group_desc]) {
-		ext2_error (sb, "ext2_get_group_desc",
-			    "Group descriptor not loaded - "
-			    "block_group = %d, group_desc = %lu, desc = %lu",
-			     block_group, group_desc, offset);
+		WARN(1, "Group descriptor not loaded - "
+		     "block_group = %d, group_desc = %lu, desc = %lu",
+		      block_group, group_desc, offset);
 		return NULL;
 	}
 
-- 
2.33.0