Re: [PATCH 3/3] xfs: make fsmap backend function key parameters const

[Chandan Babu R <chandanrlinux@gmail.com>]

On 11 Aug 2021 at 17:58, "Darrick J. Wong" <djwong@kernel.org> wrote:
> From: Darrick J. Wong <djwong@kernel.org>
>
> There are several GETFSMAP backend functions for XFS to cover the three
> devices and various feature support.  Each of these functions are passed
> pointers to the low and high keys for the dataset that userspace
> requested, and a pointer to scratchpad variables that are used to
> control the iteration and fill out records.  The scratchpad data can be
> changed arbitrarily, but the keys are supposed to remain unchanged (and
> under the control of the outermost loop in xfs_getfsmap).
>
> Unfortunately, the data and rt backends modify the keys that are passed
> in from the main control loop, which causes subsequent calls to return
> incorrect query results.  Specifically, each of those two functions set
> the block number in the high key to the size of their respective device.
> Since fsmap results are sorted in device number order, if the lower
> numbered device is smaller than the higher numbered device, the first
> function will set the high key to the small size, and the key remains
> unchanged as it is passed into the function for the higher numbered
> device.  The second function will then fail to return all of the results
> for the dataset that userspace is asking for because the keyspace is
> incorrectly constrained.
>

Looks good.

Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  fs/xfs/xfs_fsmap.c |   30 +++++++++++++-----------------
>  1 file changed, 13 insertions(+), 17 deletions(-)
>
>
> diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
> index a0e8ab58124b..7bcc2ab68b8d 100644
> --- a/fs/xfs/xfs_fsmap.c
> +++ b/fs/xfs/xfs_fsmap.c
> @@ -61,7 +61,7 @@ xfs_fsmap_to_internal(
>  static int
>  xfs_fsmap_owner_to_rmap(
>  	struct xfs_rmap_irec	*dest,
> -	struct xfs_fsmap	*src)
> +	const struct xfs_fsmap	*src)
>  {
>  	if (!(src->fmr_flags & FMR_OF_SPECIAL_OWNER)) {
>  		dest->rm_owner = src->fmr_owner;
> @@ -171,7 +171,7 @@ struct xfs_getfsmap_info {
>  struct xfs_getfsmap_dev {
>  	u32			dev;
>  	int			(*fn)(struct xfs_trans *tp,
> -				      struct xfs_fsmap *keys,
> +				      const struct xfs_fsmap *keys,
>  				      struct xfs_getfsmap_info *info);
>  };
>  
> @@ -389,7 +389,7 @@ xfs_getfsmap_datadev_bnobt_helper(
>  static void
>  xfs_getfsmap_set_irec_flags(
>  	struct xfs_rmap_irec	*irec,
> -	struct xfs_fsmap	*fmr)
> +	const struct xfs_fsmap	*fmr)
>  {
>  	irec->rm_flags = 0;
>  	if (fmr->fmr_flags & FMR_OF_ATTR_FORK)
> @@ -404,7 +404,7 @@ xfs_getfsmap_set_irec_flags(
>  STATIC int
>  xfs_getfsmap_logdev(
>  	struct xfs_trans		*tp,
> -	struct xfs_fsmap		*keys,
> +	const struct xfs_fsmap		*keys,
>  	struct xfs_getfsmap_info	*info)
>  {
>  	struct xfs_mount		*mp = tp->t_mountp;
> @@ -473,7 +473,7 @@ xfs_getfsmap_rtdev_rtbitmap_helper(
>  STATIC int
>  __xfs_getfsmap_rtdev(
>  	struct xfs_trans		*tp,
> -	struct xfs_fsmap		*keys,
> +	const struct xfs_fsmap		*keys,
>  	int				(*query_fn)(struct xfs_trans *,
>  						    struct xfs_getfsmap_info *),
>  	struct xfs_getfsmap_info	*info)
> @@ -481,16 +481,14 @@ __xfs_getfsmap_rtdev(
>  	struct xfs_mount		*mp = tp->t_mountp;
>  	xfs_fsblock_t			start_fsb;
>  	xfs_fsblock_t			end_fsb;
> -	xfs_daddr_t			eofs;
> +	uint64_t			eofs;
>  	int				error = 0;
>  
>  	eofs = XFS_FSB_TO_BB(mp, mp->m_sb.sb_rblocks);
>  	if (keys[0].fmr_physical >= eofs)
>  		return 0;
> -	if (keys[1].fmr_physical >= eofs)
> -		keys[1].fmr_physical = eofs - 1;
>  	start_fsb = XFS_BB_TO_FSBT(mp, keys[0].fmr_physical);
> -	end_fsb = XFS_BB_TO_FSB(mp, keys[1].fmr_physical);
> +	end_fsb = XFS_BB_TO_FSB(mp, min(eofs - 1, keys[1].fmr_physical));
>  
>  	/* Set up search keys */
>  	info->low.rm_startblock = start_fsb;
> @@ -563,7 +561,7 @@ xfs_getfsmap_rtdev_rtbitmap_query(
>  STATIC int
>  xfs_getfsmap_rtdev_rtbitmap(
>  	struct xfs_trans		*tp,
> -	struct xfs_fsmap		*keys,
> +	const struct xfs_fsmap		*keys,
>  	struct xfs_getfsmap_info	*info)
>  {
>  	info->missing_owner = XFS_FMR_OWN_UNKNOWN;
> @@ -576,7 +574,7 @@ xfs_getfsmap_rtdev_rtbitmap(
>  STATIC int
>  __xfs_getfsmap_datadev(
>  	struct xfs_trans		*tp,
> -	struct xfs_fsmap		*keys,
> +	const struct xfs_fsmap		*keys,
>  	struct xfs_getfsmap_info	*info,
>  	int				(*query_fn)(struct xfs_trans *,
>  						    struct xfs_getfsmap_info *,
> @@ -591,16 +589,14 @@ __xfs_getfsmap_datadev(
>  	xfs_fsblock_t			end_fsb;
>  	xfs_agnumber_t			start_ag;
>  	xfs_agnumber_t			end_ag;
> -	xfs_daddr_t			eofs;
> +	uint64_t			eofs;
>  	int				error = 0;
>  
>  	eofs = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
>  	if (keys[0].fmr_physical >= eofs)
>  		return 0;
> -	if (keys[1].fmr_physical >= eofs)
> -		keys[1].fmr_physical = eofs - 1;
>  	start_fsb = XFS_DADDR_TO_FSB(mp, keys[0].fmr_physical);
> -	end_fsb = XFS_DADDR_TO_FSB(mp, keys[1].fmr_physical);
> +	end_fsb = XFS_DADDR_TO_FSB(mp, min(eofs - 1, keys[1].fmr_physical));
>  
>  	/*
>  	 * Convert the fsmap low/high keys to AG based keys.  Initialize
> @@ -728,7 +724,7 @@ xfs_getfsmap_datadev_rmapbt_query(
>  STATIC int
>  xfs_getfsmap_datadev_rmapbt(
>  	struct xfs_trans		*tp,
> -	struct xfs_fsmap		*keys,
> +	const struct xfs_fsmap		*keys,
>  	struct xfs_getfsmap_info	*info)
>  {
>  	info->missing_owner = XFS_FMR_OWN_FREE;
> @@ -763,7 +759,7 @@ xfs_getfsmap_datadev_bnobt_query(
>  STATIC int
>  xfs_getfsmap_datadev_bnobt(
>  	struct xfs_trans		*tp,
> -	struct xfs_fsmap		*keys,
> +	const struct xfs_fsmap		*keys,
>  	struct xfs_getfsmap_info	*info)
>  {
>  	struct xfs_alloc_rec_incore	akeys[2];


-- 
chandan