Re: [PATCH 1/9] xfs: simplify mappedbno case from xfs_da_get_buf and xfs_da_read_buf

Darrick J. Wong
2019-11-18T21:21:36Z

On Sat, Nov 16, 2019 at 07:22:06PM +0100, Christoph Hellwig wrote:
> Shortcut the creation of xfs_bmbt_irec and xfs_buf_map for the case
> where the callers passed an already mapped xfs_daddr_t. This is in
> preparation for splitting these cases out entirely later. Also reject
> the mappedbno case for xfs_da_reada_buf as no callers currently uses
> it and it will be removed soon.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks reasonable,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> fs/xfs/libxfs/xfs_da_btree.c | 103 +++++++++++++++++------------------
> 1 file changed, 51 insertions(+), 52 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
> index 46b1c3fb305c..681fba5731c2 100644
> --- a/fs/xfs/libxfs/xfs_da_btree.c
> +++ b/fs/xfs/libxfs/xfs_da_btree.c
> @@ -110,6 +110,13 @@ xfs_da_state_free(xfs_da_state_t *state)
> kmem_zone_free(xfs_da_state_zone, state);
> }
>
> +static inline int xfs_dabuf_nfsb(struct xfs_mount *mp, int whichfork)
> +{
> + if (whichfork == XFS_DATA_FORK)
> + return mp->m_dir_geo->fsbcount;
> + return mp->m_attr_geo->fsbcount;
> +}
> +
> void
> xfs_da3_node_hdr_from_disk(
> struct xfs_mount *mp,
> @@ -2570,7 +2577,7 @@ xfs_dabuf_map(
> int *nmaps)
> {
> struct xfs_mount *mp = dp->i_mount;
> - int nfsb;
> + int nfsb = xfs_dabuf_nfsb(mp, whichfork);
> int error = 0;
> struct xfs_bmbt_irec irec;
> struct xfs_bmbt_irec *irecs = &irec;
> @@ -2579,35 +2586,13 @@ xfs_dabuf_map(
> ASSERT(map && *map);
> ASSERT(*nmaps == 1);
>
> - if (whichfork == XFS_DATA_FORK)
> - nfsb = mp->m_dir_geo->fsbcount;
> - else
> - nfsb = mp->m_attr_geo->fsbcount;
> -
> - /*
> - * Caller doesn't have a mapping. -2 means don't complain
> - * if we land in a hole.
> - */
> - if (mappedbno == -1 || mappedbno == -2) {
> - /*
> - * Optimize the one-block case.
> - */
> - if (nfsb != 1)
> - irecs = kmem_zalloc(sizeof(irec) * nfsb,
> - KM_NOFS);
> -
> - nirecs = nfsb;
> - error = xfs_bmapi_read(dp, (xfs_fileoff_t)bno, nfsb, irecs,
> - &nirecs, xfs_bmapi_aflag(whichfork));
> - if (error)
> - goto out;
> - } else {
> - irecs->br_startblock = XFS_DADDR_TO_FSB(mp, mappedbno);
> - irecs->br_startoff = (xfs_fileoff_t)bno;
> - irecs->br_blockcount = nfsb;
> - irecs->br_state = 0;
> - nirecs = 1;
> - }
> + if (nfsb != 1)
> + irecs = kmem_zalloc(sizeof(irec) * nfsb, KM_NOFS);
> + nirecs = nfsb;
> + error = xfs_bmapi_read(dp, (xfs_fileoff_t)bno, nfsb, irecs,
> + &nirecs, xfs_bmapi_aflag(whichfork));
> + if (error)
> + goto out;
>
> if (!xfs_da_map_covers_blocks(nirecs, irecs, bno, nfsb)) {
> /* Caller ok with no mapping. */
> @@ -2648,24 +2633,29 @@ xfs_dabuf_map(
> */
> int
> xfs_da_get_buf(
> - struct xfs_trans *trans,
> + struct xfs_trans *tp,
> struct xfs_inode *dp,
> xfs_dablk_t bno,
> xfs_daddr_t mappedbno,
> struct xfs_buf **bpp,
> int whichfork)
> {
> + struct xfs_mount *mp = dp->i_mount;
> struct xfs_buf *bp;
> - struct xfs_buf_map map;
> - struct xfs_buf_map *mapp;
> - int nmap;
> + struct xfs_buf_map map, *mapp = &map;
> + int nmap = 1;
> int error;
>
> *bpp = NULL;
> - mapp = &map;
> - nmap = 1;
> - error = xfs_dabuf_map(dp, bno, mappedbno, whichfork,
> - &mapp, &nmap);
> +
> + if (mappedbno >= 0) {
> + bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, mappedbno,
> + XFS_FSB_TO_BB(mp,
> + xfs_dabuf_nfsb(mp, whichfork)), 0);
> + goto done;
> + }
> +
> + error = xfs_dabuf_map(dp, bno, mappedbno, whichfork, &mapp, &nmap);
> if (error) {
> /* mapping a hole is not an error, but we don't continue */
> if (error == -1)
> @@ -2673,12 +2663,12 @@ xfs_da_get_buf(
> goto out_free;
> }
>
> - bp = xfs_trans_get_buf_map(trans, dp->i_mount->m_ddev_targp,
> - mapp, nmap, 0);
> + bp = xfs_trans_get_buf_map(tp, mp->m_ddev_targp, mapp, nmap, 0);
> +done:
> error = bp ? bp->b_error : -EIO;
> if (error) {
> if (bp)
> - xfs_trans_brelse(trans, bp);
> + xfs_trans_brelse(tp, bp);
> goto out_free;
> }
>
> @@ -2696,7 +2686,7 @@ xfs_da_get_buf(
> */
> int
> xfs_da_read_buf(
> - struct xfs_trans *trans,
> + struct xfs_trans *tp,
> struct xfs_inode *dp,
> xfs_dablk_t bno,
> xfs_daddr_t mappedbno,
> @@ -2704,17 +2694,23 @@ xfs_da_read_buf(
> int whichfork,
> const struct xfs_buf_ops *ops)
> {
> + struct xfs_mount *mp = dp->i_mount;
> struct xfs_buf *bp;
> - struct xfs_buf_map map;
> - struct xfs_buf_map *mapp;
> - int nmap;
> + struct xfs_buf_map map, *mapp = &map;
> + int nmap = 1;
> int error;
>
> *bpp = NULL;
> - mapp = &map;
> - nmap = 1;
> - error = xfs_dabuf_map(dp, bno, mappedbno, whichfork,
> - &mapp, &nmap);
> +
> + if (mappedbno >= 0) {
> + error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
> + mappedbno, XFS_FSB_TO_BB(mp,
> + xfs_dabuf_nfsb(mp, whichfork)),
> + 0, &bp, ops);
> + goto done;
> + }
> +
> + error = xfs_dabuf_map(dp, bno, mappedbno, whichfork, &mapp, &nmap);
> if (error) {
> /* mapping a hole is not an error, but we don't continue */
> if (error == -1)
> @@ -2722,9 +2718,9 @@ xfs_da_read_buf(
> goto out_free;
> }
>
> - error = xfs_trans_read_buf_map(dp->i_mount, trans,
> - dp->i_mount->m_ddev_targp,
> - mapp, nmap, 0, &bp, ops);
> + error = xfs_trans_read_buf_map(mp, tp, mp->m_ddev_targp, mapp, nmap, 0,
> + &bp, ops);
> +done:
> if (error)
> goto out_free;
>
> @@ -2756,6 +2752,9 @@ xfs_da_reada_buf(
> int nmap;
> int error;
>
> + if (mappedbno >= 0)
> + return -EINVAL;
> +
> mapp = &map;
> nmap = 1;
> error = xfs_dabuf_map(dp, bno, mappedbno, whichfork,
> --
> 2.20.1
>