Re: [PATCH 02/10] xfs: refactor xfs_dabuf_map

Darrick J. Wong
2019-11-20T18:24:41Z

On Wed, Nov 20, 2019 at 12:17:19PM +0100, Christoph Hellwig wrote:
> Merge xfs_buf_map_from_irec and xfs_da_map_covers_blocks into a single
> loop in the caller.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

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

--D

> ---
> fs/xfs/libxfs/xfs_da_btree.c | 156 ++++++++++++-----------------------
> 1 file changed, 54 insertions(+), 102 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
> index f3087f061a48..e078817fc26c 100644
> --- a/fs/xfs/libxfs/xfs_da_btree.c
> +++ b/fs/xfs/libxfs/xfs_da_btree.c
> @@ -2460,74 +2460,6 @@ xfs_da_shrink_inode(
> return error;
> }
>
> -/*
> - * See if the mapping(s) for this btree block are valid, i.e.
> - * don't contain holes, are logically contiguous, and cover the whole range.
> - */
> -STATIC int
> -xfs_da_map_covers_blocks(
> - int nmap,
> - xfs_bmbt_irec_t *mapp,
> - xfs_dablk_t bno,
> - int count)
> -{
> - int i;
> - xfs_fileoff_t off;
> -
> - for (i = 0, off = bno; i < nmap; i++) {
> - if (mapp[i].br_startblock == HOLESTARTBLOCK ||
> - mapp[i].br_startblock == DELAYSTARTBLOCK) {
> - return 0;
> - }
> - if (off != mapp[i].br_startoff) {
> - return 0;
> - }
> - off += mapp[i].br_blockcount;
> - }
> - return off == bno + count;
> -}
> -
> -/*
> - * Convert a struct xfs_bmbt_irec to a struct xfs_buf_map.
> - *
> - * For the single map case, it is assumed that the caller has provided a pointer
> - * to a valid xfs_buf_map. For the multiple map case, this function will
> - * allocate the xfs_buf_map to hold all the maps and replace the caller's single
> - * map pointer with the allocated map.
> - */
> -static int
> -xfs_buf_map_from_irec(
> - struct xfs_mount *mp,
> - struct xfs_buf_map **mapp,
> - int *nmaps,
> - struct xfs_bmbt_irec *irecs,
> - int nirecs)
> -{
> - struct xfs_buf_map *map;
> - int i;
> -
> - ASSERT(*nmaps == 1);
> - ASSERT(nirecs >= 1);
> -
> - if (nirecs > 1) {
> - map = kmem_zalloc(nirecs * sizeof(struct xfs_buf_map),
> - KM_NOFS);
> - if (!map)
> - return -ENOMEM;
> - *mapp = map;
> - }
> -
> - *nmaps = nirecs;
> - map = *mapp;
> - for (i = 0; i < *nmaps; i++) {
> - ASSERT(irecs[i].br_startblock != DELAYSTARTBLOCK &&
> - irecs[i].br_startblock != HOLESTARTBLOCK);
> - map[i].bm_bn = XFS_FSB_TO_DADDR(mp, irecs[i].br_startblock);
> - map[i].bm_len = XFS_FSB_TO_BB(mp, irecs[i].br_blockcount);
> - }
> - return 0;
> -}
> -
> /*
> * Map the block we are given ready for reading. There are three possible return
> * values:
> @@ -2542,58 +2474,78 @@ xfs_dabuf_map(
> xfs_dablk_t bno,
> xfs_daddr_t mappedbno,
> int whichfork,
> - struct xfs_buf_map **map,
> + struct xfs_buf_map **mapp,
> int *nmaps)
> {
> struct xfs_mount *mp = dp->i_mount;
> int nfsb = xfs_dabuf_nfsb(mp, whichfork);
> - int error = 0;
> - struct xfs_bmbt_irec irec;
> - struct xfs_bmbt_irec *irecs = &irec;
> - int nirecs;
> -
> - ASSERT(map && *map);
> - ASSERT(*nmaps == 1);
> + struct xfs_bmbt_irec irec, *irecs = &irec;
> + struct xfs_buf_map *map = *mapp;
> + xfs_fileoff_t off = bno;
> + int error = 0, nirecs, i;
>
> - if (nfsb != 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));
> + error = xfs_bmapi_read(dp, bno, nfsb, irecs, &nirecs,
> + xfs_bmapi_aflag(whichfork));
> if (error)
> - goto out;
> + goto out_free_irecs;
>
> - if (!xfs_da_map_covers_blocks(nirecs, irecs, bno, nfsb)) {
> - /* Caller ok with no mapping. */
> - if (!XFS_IS_CORRUPT(mp, mappedbno != -2)) {
> - error = -1;
> - goto out;
> - }
> + /*
> + * Use the caller provided map for the single map case, else allocate a
> + * larger one that needs to be free by the caller.
> + */
> + if (nirecs > 1) {
> + map = kmem_zalloc(nirecs * sizeof(struct xfs_buf_map), KM_NOFS);
> + if (!map)
> + goto out_free_irecs;
> + *mapp = map;
> + }
>
> - /* Caller expected a mapping, so abort. */
> + for (i = 0; i < nirecs; i++) {
> + if (irecs[i].br_startblock == HOLESTARTBLOCK ||
> + irecs[i].br_startblock == DELAYSTARTBLOCK)
> + goto invalid_mapping;
> + if (off != irecs[i].br_startoff)
> + goto invalid_mapping;
> +
> + map[i].bm_bn = XFS_FSB_TO_DADDR(mp, irecs[i].br_startblock);
> + map[i].bm_len = XFS_FSB_TO_BB(mp, irecs[i].br_blockcount);
> + off += irecs[i].br_blockcount;
> + }
> +
> + if (off != bno + nfsb)
> + goto invalid_mapping;
> +
> + *nmaps = nirecs;
> +out_free_irecs:
> + if (irecs != &irec)
> + kmem_free(irecs);
> + return error;
> +
> +invalid_mapping:
> + /* Caller ok with no mapping. */
> + if (XFS_IS_CORRUPT(mp, mappedbno != -2)) {
> + error = -EFSCORRUPTED;
> if (xfs_error_level >= XFS_ERRLEVEL_LOW) {
> - int i;
> + xfs_alert(mp, "%s: bno %u inode %llu",
> + __func__, bno, dp->i_ino);
>
> - xfs_alert(mp, "%s: bno %lld dir: inode %lld", __func__,
> - (long long)bno, (long long)dp->i_ino);
> - for (i = 0; i < *nmaps; i++) {
> + for (i = 0; i < nirecs; i++) {
> xfs_alert(mp,
> "[%02d] br_startoff %lld br_startblock %lld br_blockcount %lld br_state %d",
> - i,
> - (long long)irecs[i].br_startoff,
> - (long long)irecs[i].br_startblock,
> - (long long)irecs[i].br_blockcount,
> + i, irecs[i].br_startoff,
> + irecs[i].br_startblock,
> + irecs[i].br_blockcount,
> irecs[i].br_state);
> }
> }
> - error = -EFSCORRUPTED;
> - goto out;
> + } else {
> + *nmaps = 0;
> }
> - error = xfs_buf_map_from_irec(mp, map, nmaps, irecs, nirecs);
> -out:
> - if (irecs != &irec)
> - kmem_free(irecs);
> - return error;
> + goto out_free_irecs;
> }
>
> /*
> --
> 2.20.1
>