Re: [PATCH 1/2] xfs: track the number of blocks in each buftarg

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Aug 18, 2025 at 07:11:23AM +0200, Christoph Hellwig wrote:
> Add a bt_nr_blocks to track the number of blocks in each buftarg, and
> replace the check that hard codes sb_dblock in xfs_buf_map_verify with
> this new value so that it is correct for non-ddev buftargs.  The
> RT buftarg only has a superblock in the first block, so it is unlikely
> to trigger this, or are we likely to ever have enough blocks in the
> in-memory buftargs, but we might as well get the check right.
> 
> Fixes: 10616b806d1d ("xfs: fix _xfs_buf_find oops on blocks beyond the filesystem end")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/xfs_buf.c              | 38 +++++++++++++++++++----------------
>  fs/xfs/xfs_buf.h              |  4 +++-
>  fs/xfs/xfs_buf_item_recover.c |  7 +++++++
>  fs/xfs/xfs_super.c            |  7 ++++---
>  fs/xfs/xfs_trans.c            | 21 +++++++++----------
>  5 files changed, 45 insertions(+), 32 deletions(-)
> 
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index f9ef3b2a332a..b9b89f1243a0 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -397,7 +397,7 @@ xfs_buf_map_verify(
>  	 * Corrupted block numbers can get through to here, unfortunately, so we
>  	 * have to check that the buffer falls within the filesystem bounds.
>  	 */
> -	eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
> +	eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_nr_blocks);
>  	if (map->bm_bn < 0 || map->bm_bn >= eofs) {
>  		xfs_alert(btp->bt_mount,
>  			  "%s: daddr 0x%llx out of range, EOFS 0x%llx",
> @@ -1720,26 +1720,27 @@ xfs_configure_buftarg_atomic_writes(
>  int
>  xfs_configure_buftarg(
>  	struct xfs_buftarg	*btp,
> -	unsigned int		sectorsize)
> -{
> -	int			error;
> +	unsigned int		sectorsize,
> +	xfs_rfsblock_t		nr_blocks)
> +{
> +	if (btp->bt_bdev) {
> +		int		error;
> +
> +		error = bdev_validate_blocksize(btp->bt_bdev, sectorsize);
> +		if (error) {
> +			xfs_warn(btp->bt_mount,
> +				"Cannot use blocksize %u on device %pg, err %d",
> +				sectorsize, btp->bt_bdev, error);
> +			return -EINVAL;
> +		}
>  
> -	ASSERT(btp->bt_bdev != NULL);
> +		if (bdev_can_atomic_write(btp->bt_bdev))
> +			xfs_configure_buftarg_atomic_writes(btp);
> +	}
>  
> -	/* Set up metadata sector size info */
>  	btp->bt_meta_sectorsize = sectorsize;
>  	btp->bt_meta_sectormask = sectorsize - 1;
> -
> -	error = bdev_validate_blocksize(btp->bt_bdev, sectorsize);
> -	if (error) {
> -		xfs_warn(btp->bt_mount,
> -			"Cannot use blocksize %u on device %pg, err %d",
> -			sectorsize, btp->bt_bdev, error);
> -		return -EINVAL;
> -	}
> -
> -	if (bdev_can_atomic_write(btp->bt_bdev))
> -		xfs_configure_buftarg_atomic_writes(btp);
> +	btp->bt_nr_blocks = nr_blocks;
>  	return 0;
>  }
>  
> @@ -1749,6 +1750,9 @@ xfs_init_buftarg(
>  	size_t				logical_sectorsize,
>  	const char			*descr)
>  {
> +	/* The maximum size of the buftarg is only known once the sb is read. */
> +	btp->bt_nr_blocks = (xfs_rfsblock_t)-1;
> +
>  	/* Set up device logical sector size mask */
>  	btp->bt_logical_sectorsize = logical_sectorsize;
>  	btp->bt_logical_sectormask = logical_sectorsize - 1;
> diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
> index b269e115d9ac..a9b3def89cfb 100644
> --- a/fs/xfs/xfs_buf.h
> +++ b/fs/xfs/xfs_buf.h
> @@ -103,6 +103,7 @@ struct xfs_buftarg {
>  	size_t			bt_meta_sectormask;
>  	size_t			bt_logical_sectorsize;
>  	size_t			bt_logical_sectormask;
> +	xfs_rfsblock_t		bt_nr_blocks;
>  
>  	/* LRU control structures */
>  	struct shrinker		*bt_shrinker;
> @@ -372,7 +373,8 @@ struct xfs_buftarg *xfs_alloc_buftarg(struct xfs_mount *mp,
>  extern void xfs_free_buftarg(struct xfs_buftarg *);
>  extern void xfs_buftarg_wait(struct xfs_buftarg *);
>  extern void xfs_buftarg_drain(struct xfs_buftarg *);
> -int xfs_configure_buftarg(struct xfs_buftarg *btp, unsigned int sectorsize);
> +int xfs_configure_buftarg(struct xfs_buftarg *btp, unsigned int sectorsize,
> +		xfs_rfsblock_t nr_blocks);
>  
>  #define xfs_readonly_buftarg(buftarg)	bdev_read_only((buftarg)->bt_bdev)
>  
> diff --git a/fs/xfs/xfs_buf_item_recover.c b/fs/xfs/xfs_buf_item_recover.c
> index 5d58e2ae4972..d43234e04174 100644
> --- a/fs/xfs/xfs_buf_item_recover.c
> +++ b/fs/xfs/xfs_buf_item_recover.c
> @@ -736,6 +736,13 @@ xlog_recover_do_primary_sb_buffer(
>  	 */
>  	xfs_sb_from_disk(&mp->m_sb, dsb);
>  
> +	/*
> +	 * Grow can change the device size.  Mirror that into the buftarg.
> +	 */
> +	mp->m_ddev_targp->bt_nr_blocks = mp->m_sb.sb_dblocks;
> +	if (mp->m_rtdev_targp && mp->m_rtdev_targp != mp->m_ddev_targp)
> +		mp->m_rtdev_targp->bt_nr_blocks = mp->m_sb.sb_dblocks;
> +
>  	if (mp->m_sb.sb_agcount < orig_agcount) {
>  		xfs_alert(mp, "Shrinking AG count in log recovery not supported");
>  		return -EFSCORRUPTED;
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index bb0a82635a77..78f0c4707c22 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -541,7 +541,8 @@ xfs_setup_devices(
>  {
>  	int			error;
>  
> -	error = xfs_configure_buftarg(mp->m_ddev_targp, mp->m_sb.sb_sectsize);
> +	error = xfs_configure_buftarg(mp->m_ddev_targp, mp->m_sb.sb_sectsize,
> +			mp->m_sb.sb_dblocks);
>  	if (error)
>  		return error;
>  
> @@ -551,7 +552,7 @@ xfs_setup_devices(
>  		if (xfs_has_sector(mp))
>  			log_sector_size = mp->m_sb.sb_logsectsize;
>  		error = xfs_configure_buftarg(mp->m_logdev_targp,
> -					    log_sector_size);
> +				log_sector_size, mp->m_sb.sb_logblocks);
>  		if (error)
>  			return error;
>  	}
> @@ -565,7 +566,7 @@ xfs_setup_devices(
>  		mp->m_rtdev_targp = mp->m_ddev_targp;
>  	} else if (mp->m_rtname) {
>  		error = xfs_configure_buftarg(mp->m_rtdev_targp,
> -					    mp->m_sb.sb_sectsize);
> +				mp->m_sb.sb_sectsize, mp->m_sb.sb_rblocks);
>  		if (error)
>  			return error;
>  	}
> diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
> index 575e7028f423..584bd725ef18 100644
> --- a/fs/xfs/xfs_trans.c
> +++ b/fs/xfs/xfs_trans.c
> @@ -452,19 +452,17 @@ xfs_trans_mod_sb(
>   */
>  STATIC void
>  xfs_trans_apply_sb_deltas(
> -	xfs_trans_t	*tp)
> +	struct xfs_trans	*tp)
>  {
> -	struct xfs_dsb	*sbp;
> -	struct xfs_buf	*bp;
> -	int		whole = 0;
> -
> -	bp = xfs_trans_getsb(tp);
> -	sbp = bp->b_addr;
> +	struct xfs_mount	*mp = tp->t_mountp;
> +	struct xfs_buf		*bp = xfs_trans_getsb(tp);
> +	struct xfs_dsb		*sbp = bp->b_addr;
> +	int			whole = 0;
>  
>  	/*
>  	 * Only update the superblock counters if we are logging them
>  	 */
> -	if (!xfs_has_lazysbcount((tp->t_mountp))) {
> +	if (!xfs_has_lazysbcount(mp)) {
>  		if (tp->t_icount_delta)
>  			be64_add_cpu(&sbp->sb_icount, tp->t_icount_delta);
>  		if (tp->t_ifree_delta)
> @@ -491,8 +489,7 @@ xfs_trans_apply_sb_deltas(
>  	 * write the correct value ondisk.
>  	 */
>  	if ((tp->t_frextents_delta || tp->t_res_frextents_delta) &&
> -	    !xfs_has_rtgroups(tp->t_mountp)) {
> -		struct xfs_mount	*mp = tp->t_mountp;
> +	    !xfs_has_rtgroups(mp)) {
>  		int64_t			rtxdelta;
>  
>  		rtxdelta = tp->t_frextents_delta + tp->t_res_frextents_delta;
> @@ -505,6 +502,7 @@ xfs_trans_apply_sb_deltas(
>  
>  	if (tp->t_dblocks_delta) {
>  		be64_add_cpu(&sbp->sb_dblocks, tp->t_dblocks_delta);
> +		mp->m_ddev_targp->bt_nr_blocks += tp->t_dblocks_delta;
>  		whole = 1;
>  	}
>  	if (tp->t_agcount_delta) {
> @@ -524,7 +522,7 @@ xfs_trans_apply_sb_deltas(
>  		 * recompute the ondisk rtgroup block log.  The incore values
>  		 * will be recomputed in xfs_trans_unreserve_and_mod_sb.
>  		 */
> -		if (xfs_has_rtgroups(tp->t_mountp)) {
> +		if (xfs_has_rtgroups(mp)) {
>  			sbp->sb_rgblklog = xfs_compute_rgblklog(
>  						be32_to_cpu(sbp->sb_rgextents),
>  						be32_to_cpu(sbp->sb_rextsize));
> @@ -537,6 +535,7 @@ xfs_trans_apply_sb_deltas(
>  	}
>  	if (tp->t_rblocks_delta) {
>  		be64_add_cpu(&sbp->sb_rblocks, tp->t_rblocks_delta);
> +		mp->m_rtdev_targp->bt_nr_blocks += tp->t_dblocks_delta;

Should this be += tp->t_rblocks_delta here?

--D

>  		whole = 1;
>  	}
>  	if (tp->t_rextents_delta) {
> -- 
> 2.47.2
> 
>