Commit b2bbb92f authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
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ext4: fix e2fsprogs checksum failure for mounted filesystem 



Commit 81414b4d ("ext4: remove redundant sb checksum
recomputation") removed checksum recalculation after updating
superblock free space / inode counters in ext4_fill_super() based on
the fact that we will recalculate the checksum on superblock
writeout.

That is correct assumption but until the writeout happens (which can
take a long time) the checksum is incorrect in the buffer cache and if
programs such as tune2fs or resize2fs is called shortly after a file
system is mounted can fail.  So return back the checksum recalculation
and add a comment explaining why.

Fixes: 81414b4d ("ext4: remove redundant sb checksum recomputation")
Cc: stable@kernel.org
Reported-by: default avatarBoyang Xue <bxue@redhat.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20210812124737.21981-1-jack@suse.cz
parent 308c57cc

fs/ext4/super.c

+8 −0
Original line number Diff line number Diff line
@@ -5032,6 +5032,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) 
		err = percpu_counter_init(&sbi->s_freeinodes_counter, freei,

					  GFP_KERNEL);

	}

	/*

	 * Update the checksum after updating free space/inode

	 * counters.  Otherwise the superblock can have an incorrect

	 * checksum in the buffer cache until it is written out and

	 * e2fsprogs programs trying to open a file system immediately

	 * after it is mounted can fail.

	 */

	ext4_superblock_csum_set(sb);

	if (!err)

		err = percpu_counter_init(&sbi->s_dirs_counter,

					  ext4_count_dirs(sb), GFP_KERNEL);