ext4: fix scheduling in atomic on group checksum failure

When block group checksum is wrong, we call ext4_error() while holding
group spinlock from ext4_init_block_bitmap() or
ext4_init_inode_bitmap() which results in scheduling while in atomic.
Fix the issue by calling ext4_error() later after dropping the spinlock.

CC: stable@vger.kernel.org
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

2 files changed, 8 insertions, 5 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index ec0668a60678..fe1f50fe764f 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -191,7 +191,6 @@ static int ext4_init_block_bitmap(struct super_block *sb,
         /* If checksum is bad mark all blocks used to prevent allocation
          * essentially implementing a per-group read-only flag. */
         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
-                ext4_error(sb, "Checksum bad for group %u", block_group);
                 grp = ext4_get_group_info(sb, block_group);
                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
                         percpu_counter_sub(&sbi->s_freeclusters_counter,
@@ -442,14 +441,16 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
         }
         ext4_lock_group(sb, block_group);
         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
-
                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
                 set_bitmap_uptodate(bh);
                 set_buffer_uptodate(bh);
                 ext4_unlock_group(sb, block_group);
                 unlock_buffer(bh);
-                if (err)
+                if (err) {
+                        ext4_error(sb, "Failed to init block bitmap for group "
+                                   "%u: %d", block_group, err);
                         goto out;
+                }
                 goto verify;
         }
         ext4_unlock_group(sb, block_group);
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 3fcfd50a2e8a..acc0ad56bf2f 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -76,7 +76,6 @@ static int ext4_init_inode_bitmap(struct super_block *sb,
         /* If checksum is bad mark all blocks and inodes use to prevent
          * allocation, essentially implementing a per-group read-only flag. */
         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
-                ext4_error(sb, "Checksum bad for group %u", block_group);
                 grp = ext4_get_group_info(sb, block_group);
                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
                         percpu_counter_sub(&sbi->s_freeclusters_counter,
@@ -191,8 +190,11 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                 set_buffer_verified(bh);
                 ext4_unlock_group(sb, block_group);
                 unlock_buffer(bh);
-                if (err)
+                if (err) {
+                        ext4_error(sb, "Failed to init inode bitmap for group "
+                                   "%u: %d", block_group, err);
                         goto out;
+                }
                 return bh;
         }
         ext4_unlock_group(sb, block_group);