Re: 2.6.24.3 bug in sysfs with md.
From: Neil Brown
Date: Mon Mar 24 2008 - 23:53:20 EST
On Saturday March 22, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> On Sat, 22 Mar 2008 18:25:31 -0400 Wakko Warner <wakko@xxxxxxxxxxxx> wrote:
>
> > I was poking around with the files laying in /sys/block/md*/md/dev-*/super
> > and found this bug (NOTE: I attempted to read the file 2 times):
> >
> > [ 5591.212764] ------------[ cut here ]------------
> > [ 5591.212773] kernel BUG at /usr/src/linux/dist/2.6.24.3/fs/sysfs/file.c:126!
>
> hm, I didn't know 2.6.24 was affected.
$ git describe 8118a859dc7abd873193986c77a8d9bdb877adc8
v2.6.24-rc3-412-g8118a85
Looks like everything since 2.6.24-rc3 is affected.
>
> Neil, should we backport this?
Yes, I think that would be best.
Thanks,
NeilBrown
>
>
> From: Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>
> To: git-commits-head@xxxxxxxxxxxxxxx
> Subject: md: remove the 'super' sysfs attribute from devices in an 'md' array
> Date: Thu, 20 Mar 2008 02:59:10 GMT
> Sender: git-commits-head-owner@xxxxxxxxxxxxxxx
>
> Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0e82989d95cc46cc58622381eafa54f7428ee679
> Commit: 0e82989d95cc46cc58622381eafa54f7428ee679
> Parent: 43d8eac44f28d384d2377dcdd1407f51f79dda55
> Author: NeilBrown <neilb@xxxxxxx>
> AuthorDate: Wed Mar 19 17:00:44 2008 -0700
> Committer: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> CommitDate: Wed Mar 19 18:53:35 2008 -0700
>
> md: remove the 'super' sysfs attribute from devices in an 'md' array
>
> Exposing the binary blob which is the md 'super-block' via sysfs doesn't
> really fit with the whole sysfs model, and ever since commit
> 8118a859dc7abd873193986c77a8d9bdb877adc8 ("sysfs: fix off-by-one error
> in fill_read_buffer()") it doesn't actually work at all (as the size of
> the blob is often one page).
>
> (akpm: as in, fs/sysfs/file.c:fill_read_buffer() goes BUG)
>
> So just remove it altogether. It isn't really useful.
>
> Signed-off-by: Neil Brown <neilb@xxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/md/md.c | 12 ------------
> 1 files changed, 0 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index ccbbf63..61ccbd2 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -1864,17 +1864,6 @@ static struct rdev_sysfs_entry rdev_state =
> __ATTR(state, S_IRUGO|S_IWUSR, state_show, state_store);
>
> static ssize_t
> -super_show(mdk_rdev_t *rdev, char *page)
> -{
> - if (rdev->sb_loaded && rdev->sb_size) {
> - memcpy(page, page_address(rdev->sb_page), rdev->sb_size);
> - return rdev->sb_size;
> - } else
> - return 0;
> -}
> -static struct rdev_sysfs_entry rdev_super = __ATTR_RO(super);
> -
> -static ssize_t
> errors_show(mdk_rdev_t *rdev, char *page)
> {
> return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
> @@ -2060,7 +2049,6 @@ __ATTR(size, S_IRUGO|S_IWUSR, rdev_size_show, rdev_size_store);
>
> static struct attribute *rdev_default_attrs[] = {
> &rdev_state.attr,
> - &rdev_super.attr,
> &rdev_errors.attr,
> &rdev_slot.attr,
> &rdev_offset.attr,
> --
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