linux-ext4 - Re: [PATCH] Correction to check

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Message-Id: <1172058571.3145.5.camel@garfield>
Date:	Wed, 21 Feb 2007 17:19:31 +0530
From:	Kalpak Shah <kalpak@...sterfs.com>
To:	tytso <tytso@....edu>
Cc:	Andreas Dilger <adilger@...sterfs.com>,
	linux-ext4 <linux-ext4@...r.kernel.org>,
	Lustre-discuss <Lustre-discuss@...sterfs.com>
Subject: Re: [PATCH] Correction to check_filetype()

Hi,

The other issue this brings up is maybe pass1 should be checking whether it is the inode mode that is corrupted (by trying to verify block[0] has "." and ".."in it) instead of truncating off those blocks. This would actually be a redundant check as pass2 would also make the same check. 

We can have some more checks like if i_blocks!=0 then the file may not be special file, etc. Does e2fsck need to have more such checks to avoid making decisions just based on the mode?

Thanks,
Kalpak.

On Wed, 2007-02-21 at 14:45 +0530, Kalpak Shah wrote: 
> Hi,
> 
> If the mode of a directory gets corrupted, check_filetype() makes wrong decisions for all its sub-directories. For example, using debugfs we can corrupt the mode of a directory to 0140755 (i.e. a socket). e2fsck will set the filetype of all its subdirectories as 6 (filetype for socket). All the subdirectories would be moved to lost+found, and in second run of e2fsck their filetype would be set back to 2.
> 
> By the time we come to check_filetype(), we have already verified the "." and ".." entries, so we special case these dirents in check_filetype().
> 
> Please consider for review.
> 
> Signed-off-by: Andreas Dilger <adilger@...sterfs.com>
> Signed-off-by: Kalpak Shah <kalpak@...sterfs.com>
> 
> 
> Index: e2fsprogs-1.39/e2fsck/pass2.c
> ===================================================================
> --- e2fsprogs-1.39.orig/e2fsck/pass2.c
> +++ e2fsprogs-1.39/e2fsck/pass2.c
> @@ -495,7 +495,9 @@ static _INLINE_ int check_filetype(e2fsc
>                 return 1;
>         }
> 
> -       if (ext2fs_test_inode_bitmap(ctx->inode_dir_map, dirent->inode)) {
> +       if (ext2fs_test_inode_bitmap(ctx->inode_dir_map, dirent->inode) ||
> +           ((dirent->name_len && 0xFF) <= 2 && dirent->name[0] == '.' &&
> +            (dirent->name[1] == '.' || dirent->name[1] == '\0'))) {
>                 should_be = EXT2_FT_DIR;
>         } else if (ext2fs_test_inode_bitmap(ctx->inode_reg_map,
>                                             dirent->inode)) {
> 
> 
> -
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