Re: [PATCH] xfs: fix delalloc quota accounting on failure

[Eric Sandeen <sandeen@sandeen.net>]

On 5/8/12 5:48 AM, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> xfstest 270 was causing quota reservations way beyond what was sane
> (ten to hundreds of TB) for a 4GB filesystem. There's a sign problem
> in the error handling path of xfs_bmapi_reserve_delalloc() because
> xfs_trans_unreserve_quota_nblks() simple negates the value passed -
> which doesn't work for an unsigned variable. This causes
> reservations of close to 2^32 block instead of removing a
> reservation of a handful of blocks.
> 
> Fix the same problem in the other xfs_trans_unreserve_quota_nblks()
> callers where unsigned integer variables are used, too.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>

Ouch!

Reviewed-by: Eric Sandeen <sandeen@redhat.com>
as far as it goes, but a couple thoughts:

1) Should the cast be done in the macro so new callers don't get tripped up?
2) Should we just remove the ninos argument from the macro?  It's always passed as 0 (and could potentially suffer the same problem)

something like:

diff --git a/fs/xfs/xfs_quota.h b/fs/xfs/xfs_quota.h
index b50ec5b..f771838 100644
--- a/fs/xfs/xfs_quota.h
+++ b/fs/xfs/xfs_quota.h
@@ -370,8 +370,8 @@ static inline int xfs_trans_reserve_quota_bydquots(struct xfs_trans *tp,
 #define xfs_qm_unmount_quotas(mp)
 #endif /* CONFIG_XFS_QUOTA */
 
-#define xfs_trans_unreserve_quota_nblks(tp, ip, nblks, ninos, flags) \
-	xfs_trans_reserve_quota_nblks(tp, ip, -(nblks), -(ninos), flags)
+#define xfs_trans_unreserve_quota_nblks(tp, ip, nblks, flags) \
+	xfs_trans_reserve_quota_nblks(tp, ip, -((long)nblks), 0, flags)
 #define xfs_trans_reserve_quota(tp, mp, ud, gd, nb, ni, f) \
 	xfs_trans_reserve_quota_bydquots(tp, mp, ud, gd, nb, ni, \
 				f | XFS_QMOPT_RES_REGBLKS)


> ---
>  fs/xfs/xfs_bmap.c     |    2 +-
>  fs/xfs/xfs_iomap.c    |    2 +-
>  fs/xfs/xfs_vnodeops.c |    2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
> index 9006656..2115146 100644
> --- a/fs/xfs/xfs_bmap.c
> +++ b/fs/xfs/xfs_bmap.c
> @@ -4526,7 +4526,7 @@ out_unreserve_blocks:
>  		xfs_icsb_modify_counters(mp, XFS_SBS_FDBLOCKS, alen, 0);
>  out_unreserve_quota:
>  	if (XFS_IS_QUOTA_ON(mp))
> -		xfs_trans_unreserve_quota_nblks(NULL, ip, alen, 0, rt ?
> +		xfs_trans_unreserve_quota_nblks(NULL, ip, (long)alen, 0, rt ?
>  				XFS_QMOPT_RES_RTBLKS : XFS_QMOPT_RES_REGBLKS);
>  	return error;
>  }
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 756f093..973dff6 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -246,7 +246,7 @@ out_unlock:
>  
>  out_bmap_cancel:
>  	xfs_bmap_cancel(&free_list);
> -	xfs_trans_unreserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
> +	xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
>  out_trans_cancel:
>  	xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
>  	goto out_unlock;
> diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
> index 57515e2..c22f4e0 100644
> --- a/fs/xfs/xfs_vnodeops.c
> +++ b/fs/xfs/xfs_vnodeops.c
> @@ -1916,7 +1916,7 @@ xfs_alloc_file_space(
>  
>  error0:	/* Cancel bmap, unlock inode, unreserve quota blocks, cancel trans */
>  	xfs_bmap_cancel(&free_list);
> -	xfs_trans_unreserve_quota_nblks(tp, ip, qblocks, 0, quota_flag);
> +	xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag);
>  
>  error1:	/* Just cancel transaction */
>  	xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);

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