Re: [PATCH] ext4: fix rec_len verify error

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Sep 22, 2023 at 01:39:15PM +0800, zhangshida wrote:
> From: Shida Zhang <zhangshida@kylinos.cn>
> 
> [ Upstream commit 7fda67e8c3ab6069f75888f67958a6d30454a9f6 ]
> 
> With the configuration PAGE_SIZE 64k and filesystem blocksize 64k,
> a problem occurred when more than 13 million files were directly created
> under a directory:
> 
> EXT4-fs error (device xx): ext4_dx_csum_set:492: inode #xxxx: comm xxxxx: dir seems corrupt?  Run e2fsck -D.
> EXT4-fs error (device xx): ext4_dx_csum_verify:463: inode #xxxx: comm xxxxx: dir seems corrupt?  Run e2fsck -D.
> EXT4-fs error (device xx): dx_probe:856: inode #xxxx: block 8188: comm xxxxx: Directory index failed checksum
> 
> When enough files are created, the fake_dirent->reclen will be 0xffff.
> it doesn't equal to the blocksize 65536, i.e. 0x10000.
> 
> But it is not the same condition when blocksize equals to 4k.
> when enough files are created, the fake_dirent->reclen will be 0x1000.
> it equals to the blocksize 4k, i.e. 0x1000.
> 
> The problem seems to be related to the limitation of the 16-bit field
> when the blocksize is set to 64k.
> To address this, helpers like ext4_rec_len_{from,to}_disk has already
> been introduced to complete the conversion between the encoded and the
> plain form of rec_len.
> 
> So fix this one by using the helper, and all the other in this file too.
> 
> Cc: stable@kernel.org
> Fixes: dbe89444042a ("ext4: Calculate and verify checksums for htree nodes")
> Suggested-by: Andreas Dilger <adilger@dilger.ca>
> Suggested-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
> Reviewed-by: Andreas Dilger <adilger@dilger.ca>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> Link: https://lore.kernel.org/r/20230803060938.1929759-1-zhangshida@kylinos.cn
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
> ---
>  fs/ext4/namei.c | 26 +++++++++++++++-----------
>  1 file changed, 15 insertions(+), 11 deletions(-)

What stable tree(s) are you asking this to be backported to?

thanks,

greg k-h