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Re: [PATCH] Make __xfs_xattr_put_listen preperly report errors.

To: Artem Savkov <asavkov@xxxxxxxxxx>
Subject: Re: [PATCH] Make __xfs_xattr_put_listen preperly report errors.
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 24 Aug 2016 11:55:51 +1000
Cc: Eric Sandeen <sandeen@xxxxxxxxxxx>, xfs@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1471967653-2561-1-git-send-email-asavkov@xxxxxxxxxx>
References: <1471967653-2561-1-git-send-email-asavkov@xxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Tue, Aug 23, 2016 at 05:54:13PM +0200, Artem Savkov wrote:
> Commit "xfs: only return -errno or success from attr ->put_listent" changes 
> the

Please quote commits in --oneline format in changelogs - it makes it
much easier to find the change you are refering to if there is both
a commit ID and the text string in the commit message. (i.e. text
string confirms the commit id is the one you meant to quote).

commit 2a6fba6 ("xfs: only return -errno or success from attr
->put_listent") is the one you are refering to here, right?

> returnvalue of __xfs_xattr_put_listen to 0 in case when there is insufficient
> space in the buffer assuming that setting context->count to -1 would be 
> enough,
> but all of the ->put_listent callers only check seen_enough. This results in
> a failed assertion:
> XFS: Assertion failed: context->count >= 0, file: fs/xfs/xfs_xattr.c, line: 
> 175
> in insufficient buffer size case.

You have a test case? Can you turn it into an xfstest? We really
need regression tests that cover issues like this....

> Signed-off-by: Artem Savkov <asavkov@xxxxxxxxxx>
> ---
>  fs/xfs/xfs_xattr.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
> index ea62245..6290093 100644
> --- a/fs/xfs/xfs_xattr.c
> +++ b/fs/xfs/xfs_xattr.c
> @@ -147,6 +147,7 @@ __xfs_xattr_put_listent(
>       arraytop = context->count + prefix_len + namelen + 1;
>       if (arraytop > context->firstu) {
>               context->count = -1;    /* insufficient space */
> +             context->seen_enough = 1;
>               return 0;
>       }
>       offset = (char *)context->alist + context->count;

Looks sane, though I don't know how to test it yet....

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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