ext4: Fix reusing stale buffer heads from last failed mounting

maillist inclusion
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6MMUV
CVE: NA

Reference: https://www.spinics.net/lists/linux-ext4/msg88237.html

--------------------------------

Following process makes ext4 load stale buffer heads from last failed
mounting in a new mounting operation:
mount_bdev
 ext4_fill_super
 | ext4_load_and_init_journal
 |  ext4_load_journal
 |   jbd2_journal_load
 |    load_superblock
 |     journal_get_superblock
 |      set_buffer_verified(bh) // buffer head is verified
 |   jbd2_journal_recover // failed caused by EIO
 | goto failed_mount3a // skip 'sb->s_root' initialization
 deactivate_locked_super
  kill_block_super
   generic_shutdown_super
    if (sb->s_root)
    // false, skip ext4_put_super->invalidate_bdev->
    // invalidate_mapping_pages->mapping_evict_folio->
    // filemap_release_folio->try_to_free_buffers, which
    // cannot drop buffer head.
   blkdev_put
    blkdev_put_whole
     if (atomic_dec_and_test(&bdev->bd_openers))
     // false, systemd-udev happens to open the device. Then
     // blkdev_flush_mapping->kill_bdev->truncate_inode_pages->
     // truncate_inode_folio->truncate_cleanup_folio->
     // folio_invalidate->block_invalidate_folio->
     // filemap_release_folio->try_to_free_buffers will be skipped,
     // dropping buffer head is missed again.

Second mount:
ext4_fill_super
 ext4_load_and_init_journal
  ext4_load_journal
   ext4_get_journal
    jbd2_journal_init_inode
     journal_init_common
      bh = getblk_unmovable
       bh = __find_get_block // Found stale bh in last failed mounting
      journal->j_sb_buffer = bh
   jbd2_journal_load
    load_superblock
     journal_get_superblock
      if (buffer_verified(bh))
      // true, skip journal->j_format_version = 2, value is 0
    jbd2_journal_recover
     do_one_pass
      next_log_block += count_tags(journal, bh)
      // According to journal_tag_bytes(), 'tag_bytes' calculating is
      // affected by jbd2_has_feature_csum3(), jbd2_has_feature_csum3()
      // returns false because 'j->j_format_version >= 2' is not true,
      // then we get wrong next_log_block. The do_one_pass may exit
      // early whenoccuring non JBD2_MAGIC_NUMBER in 'next_log_block'.

The filesystem is corrupted here, journal is partially replayed, and
new journal sequence number actually is already used by last mounting.

The invalidate_bdev() can drop all buffer heads even racing with bare
reading block device(eg. systemd-udev), so we can fix it by invalidating
bdev in error handling path in __ext4_fill_super().

Fetch a reproducer in [Link].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217171
Fixes: 25ed6e8a ("jbd2: enable journal clients to enable v2 checksumming")
Cc: stable@vger.kernel.org # v3.5
Conflicts:
	fs/ext4/super.c
	[ a7a79c29("ext4: unify the ext4 super block loading
	  operation") is not applied.
	  7edfd85b("ext4: Completely separate options parsing and sb
	  setup") is not applied. ]
Signed-off-by: NZhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: NZhang Yi <yi.zhang@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>

fs/ext4/super.c

@@ -1144,6 +1144,12 @@ static void ext4_blkdev_remove(struct ext4_sb_info *sbi)
 	struct block_device *bdev;
 	bdev = sbi->s_journal_bdev;
 	if (bdev) {
+		/*
+		 * Invalidate the journal device's buffers.  We don't want them
+		 * floating about in memory - the physical journal device may
+		 * hotswapped, and it breaks the `ro-after' testing code.
+		 */
+		invalidate_bdev(bdev);
 		ext4_blkdev_put(bdev);
 		sbi->s_journal_bdev = NULL;
 	}
@@ -1284,13 +1290,7 @@ static void ext4_put_super(struct super_block *sb)
 	sync_blockdev(sb->s_bdev);
 	invalidate_bdev(sb->s_bdev);
 	if (sbi->s_journal_bdev && sbi->s_journal_bdev != sb->s_bdev) {
-		/*
-		 * Invalidate the journal device's buffers.  We don't want them
-		 * floating about in memory - the physical journal device may
-		 * hotswapped, and it breaks the `ro-after' testing code.
-		 */
 		sync_blockdev(sbi->s_journal_bdev);
-		invalidate_bdev(sbi->s_journal_bdev);
 		ext4_blkdev_remove(sbi);
 	}
 
@@ -5279,6 +5279,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	brelse(bh);
 	ext4_blkdev_remove(sbi);
 out_fail:
+	invalidate_bdev(sb->s_bdev);
 	sb->s_fs_info = NULL;
 	kfree(sbi->s_blockgroup_lock);
 out_free_base: