On Fri, Dec 05, 2014 at 02:30:14PM -0600, Eric Sandeen wrote:
> As reported by Andy Grimm,
>
> # ln -s $( python -c 'print "a" * 260' ) /mnt/foo
>
> will succeed on xfs, but then xfs_repair will complain:
>
> component of symlink in inode 131 too long
> problem with symbolic link in inode 131
> would have cleared inode 131
>
> The kernel checks the total length of the symlink on both read
> and write, but does not look at component paths.
>
> Looking around the kernel, no other filesystem checks component
> lengths, nor does the vfs. And as Andy points out, the target
> could even be on a different filesystem, with different limitations.
>
Interesting, but we do enforce dentry name limits, yes? At least, I
can't create such a component on an XFS fs (haven't dug into where that
is enforced).
> And having a "too-long" component doesn't even seem like something
> likely to stem from disk corruption anyway, so I'm not sure why repair
> should care.
>
My guess would be the intent is based on the above, where we can't
create such a long component name and thus a component that exceeds the
limits must be "invalid."
That said, a broken symlink is generally valid and not the same as
corruption, so I think I agree that this is somewhat misplaced
functionality...
> Therefore I propose removing the component length checks from xfs_repair.
>
> Andy Grimm <agrimm@xxxxxxxxxx>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
>
> diff --git a/repair/dinode.c b/repair/dinode.c
> index 38a6562..73e4b9e 100644
> --- a/repair/dinode.c
> +++ b/repair/dinode.c
> @@ -1333,7 +1333,7 @@ process_symlink(
> xfs_dinode_t *dino,
> blkmap_t *blkmap)
> {
> - char *symlink, *cptr;
> + char *symlink;
> char data[MAXPATHLEN];
>
> /*
> @@ -1380,31 +1380,6 @@ _("found illegal null character in symlink inode %" PRIu64 "\n"),
> return(1);
> }
>
> - /*
> - * check for any component being too long
> - */
> - if (be64_to_cpu(dino->di_size) >= MAXNAMELEN) {
> - cptr = strchr(symlink, '/');
> -
> - while (cptr != NULL) {
> - if (cptr - symlink >= MAXNAMELEN) {
> - do_warn(
> -_("component of symlink in inode %" PRIu64 " too long\n"),
> - lino);
> - return(1);
> - }
> - symlink = cptr + 1;
> - cptr = strchr(symlink, '/');
> - }
> -
> - if (strlen(symlink) >= MAXNAMELEN) {
> - do_warn(
> -_("component of symlink in inode %" PRIu64 " too long\n"),
> - lino);
> - return(1);
> - }
> - }
> -
> return(0);
> }
>
>
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