linux-ext4 - Re: [PATCH] libext2fs: don't truncate the orphan file inode if it is newly allocated

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Date:   Thu, 31 Aug 2023 10:40:21 -0400
From:   Eric Whitney <enwlinux@...il.com>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Ext4 Developers List <linux-ext4@...r.kernel.org>,
        Eric Whitney <enwlinux@...il.com>
Subject: Re: [PATCH] libext2fs: don't truncate the orphan file inode if it is
 newly allocated

* Theodore Ts'o <tytso@....edu>:
> In ext2fs_create_orphan_file(), don't try truncating inode for the
> orphan file if ext2fs_create_orphan_file() allocated the inode.  This
> avoids problems where the newly allocated inode in the inode table
> might contain garbage; if the metadata checksum feature is enabled,
> this will generally result in the function failing with a checksum
> invalid error, but this can cause mke2fs (which calls
> ext2fs_create_orphan_file) to fail.
> 
> Signed-off-by: Theodore Ts'o <tytso@....edu>
> ---
>  lib/ext2fs/orphan.c | 21 ++++++++++-----------
>  1 file changed, 10 insertions(+), 11 deletions(-)
> 
> diff --git a/lib/ext2fs/orphan.c b/lib/ext2fs/orphan.c
> index e25f20ca2..c2f83567f 100644
> --- a/lib/ext2fs/orphan.c
> +++ b/lib/ext2fs/orphan.c
> @@ -127,22 +127,21 @@ errcode_t ext2fs_create_orphan_file(ext2_filsys fs, blk_t num_blocks)
>  	struct mkorphan_info oi;
>  	struct ext4_orphan_block_tail *ob_tail;
>  
> -	if (!ino) {
> +	if (ino) {
> +		err = ext2fs_read_inode(fs, ino, &inode);
> +		if (err)
> +			return err;
> +		if (EXT2_I_SIZE(&inode)) {
> +			err = ext2fs_truncate_orphan_file(fs);
> +			if (err)
> +				return err;
> +		}
> +	} else {
>  		err = ext2fs_new_inode(fs, EXT2_ROOT_INO, LINUX_S_IFREG | 0600,
>  				       0, &ino);
>  		if (err)
>  			return err;
>  		ext2fs_inode_alloc_stats2(fs, ino, +1, 0);
> -		ext2fs_mark_ib_dirty(fs);
> -	}
> -
> -	err = ext2fs_read_inode(fs, ino, &inode);
> -	if (err)
> -		return err;
> -	if (EXT2_I_SIZE(&inode)) {
> -		err = ext2fs_truncate_orphan_file(fs);
> -		if (err)
> -			return err;
>  	}
>  
>  	memset(&inode, 0, sizeof(struct ext2_inode));
> -- 
> 2.31.0
> 

With this patch to mke2fs, I ran ext4/049 on a 6.5 kernel using kvm-xfstests'
4k test scenario.  It passed 110/110 trials.  Without the patch, it fails
100% of the time.  So, it addresses the failures I've been seeing.

Thanks!

Tested-by: Eric Whitney <enwlinux@...il.com>