FAILED: patch "[PATCH] ext4: Fix reusing stale buffer heads from last failed" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x 26fb5290240dc31cae99b8b4dd2af7f46dfcba6b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023072107-action-steadily-cfc3@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

26fb5290240d ("ext4: Fix reusing stale buffer heads from last failed mounting") ee7ed3aa0f08 ("ext4: rename journal_dev to s_journal_dev inside ext4_sb_info") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570") 4dc5794cf207 ("gpio: pca9570: Add DT bindings for NXP PCA9570")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 26fb5290240dc31cae99b8b4dd2af7f46dfcba6b Mon Sep 17 00:00:00 2001
From: Zhihao Cheng <[email protected]>
Date: Wed, 15 Mar 2023 09:31:23 +0800
Subject: [PATCH] ext4: Fix reusing stale buffer heads from last failed
mounting

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].

index 7f9b087b9b20..6a8c5c3c9126 100644
@@ -1128,6 +1128,12 @@ 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;
 	}

@@ -1328,13 +1334,7 @@ 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);
 	}
 

@@ -5655,6 +5655,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 	brelse(sbi->s_sbh);
 	ext4_blkdev_remove(sbi);
 out_fail:
+	invalidate_bdev(sb->s_bdev);
 	sb->s_fs_info = NULL;
 	return err;
 }