linux-ext4 - [PATCH 1/2] ext4: fix race when setting the bitmap corrupted flag again

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Message-ID: <1545134401-104523-1-git-send-email-yi.zhang@huawei.com>
Date:   Tue, 18 Dec 2018 20:00:00 +0800
From:   "zhangyi (F)" <yi.zhang@...wei.com>
To:     <linux-ext4@...r.kernel.org>
CC:     <tytso@....edu>, <adilger.kernel@...ger.ca>, <wshilong@....com>,
        <yi.zhang@...wei.com>, <miaoxie@...wei.com>
Subject: [PATCH 1/2] ext4: fix race when setting the bitmap corrupted flag again

Commit 9af0b3d12577 "ext4: fix race when setting the bitmap corrupted
flag" want to fix race between setting inode/block bitmap corrupted
flag and reducing free group inodes/clusters counter to prevent
multiple frees. But ext4_test_and_set_bit() will invoke
__test_and_set_bit() which is non-atomic, so the race is still there.
Fix this by invoke test_and_set_bit() instead.

Fixes: 9af0b3d12577 ("ext4: fix race when setting the bitmap corrupted flag")
Signed-off-by: zhangyi (F) <yi.zhang@...wei.com>
---
 fs/ext4/ext4.h  | 6 ++++++
 fs/ext4/super.c | 6 ++----
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 3f89d0a..755ba14 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2888,6 +2888,12 @@ struct ext4_group_info {
 	(test_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &((grp)->bb_state)))
 #define EXT4_MB_GRP_IBITMAP_CORRUPT(grp)	\
 	(test_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &((grp)->bb_state)))
+#define EXT4_MB_GRP_TEST_AND_SET_BBITMAP_CORRUPT(grp)	\
+	(test_and_set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, \
+			  &((grp)->bb_state)))
+#define EXT4_MB_GRP_TEST_AND_SET_IBITMAP_CORRUPT(grp)	\
+	(test_and_set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, \
+			  &((grp)->bb_state)))
 
 #define EXT4_MB_GRP_WAS_TRIMMED(grp)	\
 	(test_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 53ff6c2..5b83765 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -798,16 +798,14 @@ void ext4_mark_group_bitmap_corrupted(struct super_block *sb,
 	int ret;
 
 	if (flags & EXT4_GROUP_INFO_BBITMAP_CORRUPT) {
-		ret = ext4_test_and_set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT,
-					    &grp->bb_state);
+		ret = EXT4_MB_GRP_TEST_AND_SET_BBITMAP_CORRUPT(grp);
 		if (!ret)
 			percpu_counter_sub(&sbi->s_freeclusters_counter,
 					   grp->bb_free);
 	}
 
 	if (flags & EXT4_GROUP_INFO_IBITMAP_CORRUPT) {
-		ret = ext4_test_and_set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT,
-					    &grp->bb_state);
+		ret = EXT4_MB_GRP_TEST_AND_SET_IBITMAP_CORRUPT(grp);
 		if (!ret && gdp) {
 			int count;
 
-- 
2.7.4