On Thu, Sep 29, 2016 at 08:09:21PM -0700, Darrick J. Wong wrote:
> Create a helper method to remove extents from the CoW fork without
> any of the side effects (rmapbt/bmbt updates) of the regular extent
> deletion routine. We'll eventually use this to clear out the CoW fork
> during ioend processing.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> v2: Use bmapi_read to iterate and trim the CoW extents instead of
> reading them raw via the iext code.
> ---
> fs/xfs/libxfs/xfs_bmap.c | 176 ++++++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/libxfs/xfs_bmap.h | 1
> 2 files changed, 177 insertions(+)
>
>
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 85a0c86..451f3e4 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -4906,6 +4906,7 @@ xfs_bmap_del_extent(
> /*
> * Matches the whole extent. Delete the entry.
> */
> + trace_xfs_bmap_pre_update(ip, *idx, state, _THIS_IP_);
> xfs_iext_remove(ip, *idx, 1,
> whichfork == XFS_ATTR_FORK ? BMAP_ATTRFORK : 0);
> --*idx;
> @@ -5123,6 +5124,181 @@ xfs_bmap_del_extent(
> }
>
> /*
> + * xfs_bunmapi_cow() -- Remove the relevant parts of the CoW fork.
> + * See xfs_bmap_del_extent.
> + * @ip: XFS inode.
> + * @idx: Extent number to delete.
> + * @del: Extent to remove.
> + */
> +int
> +xfs_bunmapi_cow(
> + xfs_inode_t *ip,
> + xfs_bmbt_irec_t *del)
> +{
> + xfs_filblks_t da_new; /* new delay-alloc indirect blocks */
> + xfs_filblks_t da_old; /* old delay-alloc indirect blocks */
> + xfs_fsblock_t del_endblock = 0;/* first block past del */
> + xfs_fileoff_t del_endoff; /* first offset past del */
> + int delay; /* current block is delayed allocated */
> + xfs_bmbt_rec_host_t *ep; /* current extent entry pointer */
> + int error; /* error return value */
> + xfs_bmbt_irec_t got; /* current extent entry */
> + xfs_fileoff_t got_endoff; /* first offset past got */
> + xfs_ifork_t *ifp; /* inode fork pointer */
> + xfs_mount_t *mp; /* mount structure */
> + xfs_filblks_t nblks; /* quota/sb block count */
> + xfs_bmbt_irec_t new; /* new record to be inserted */
> + /* REFERENCED */
> + uint qfield; /* quota field to update */
> + xfs_filblks_t temp; /* for indirect length calculations */
> + xfs_filblks_t temp2; /* for indirect length calculations */
> + int state = BMAP_COWFORK;
> + int eof;
> + xfs_extnum_t eidx;
> +
> + mp = ip->i_mount;
> + XFS_STATS_INC(mp, xs_del_exlist);
> +
> + ep = xfs_bmap_search_extents(ip, del->br_startoff, XFS_COW_FORK, &eof,
> + &eidx, &got, &new);
> +
> + ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); ifp = ifp;
> + ASSERT((eidx >= 0) && (eidx < ifp->if_bytes /
> + (uint)sizeof(xfs_bmbt_rec_t)));
The alignment above is a little wonky. E.g.:
ASSERT((eidx >= 0) &&
(eidx < ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t)));
... but it sounds like hch plans to clean this up and rework it in the
near future.
> + ASSERT(del->br_blockcount > 0);
> + ASSERT(got.br_startoff <= del->br_startoff);
> + del_endoff = del->br_startoff + del->br_blockcount;
> + got_endoff = got.br_startoff + got.br_blockcount;
> + ASSERT(got_endoff >= del_endoff);
> + delay = isnullstartblock(got.br_startblock);
> + ASSERT(isnullstartblock(del->br_startblock) == delay);
> + qfield = 0;
> + error = 0;
> + /*
> + * If deleting a real allocation, must free up the disk space.
> + */
> + if (!delay) {
> + nblks = del->br_blockcount;
> + qfield = XFS_TRANS_DQ_BCOUNT;
> + /*
> + * Set up del_endblock and cur for later.
> + */
> + del_endblock = del->br_startblock + del->br_blockcount;
> + da_old = da_new = 0;
> + } else {
> + da_old = startblockval(got.br_startblock);
> + da_new = 0;
> + nblks = 0;
> + }
> + qfield = qfield;
> + nblks = nblks;
> +
> + /*
> + * Set flag value to use in switch statement.
> + * Left-contig is 2, right-contig is 1.
> + */
> + switch (((got.br_startoff == del->br_startoff) << 1) |
> + (got_endoff == del_endoff)) {
> + case 3:
> + /*
> + * Matches the whole extent. Delete the entry.
> + */
> + xfs_iext_remove(ip, eidx, 1, BMAP_COWFORK);
> + --eidx;
> + break;
> +
> + case 2:
> + /*
> + * Deleting the first part of the extent.
> + */
> + trace_xfs_bmap_pre_update(ip, eidx, state, _THIS_IP_);
> + xfs_bmbt_set_startoff(ep, del_endoff);
> + temp = got.br_blockcount - del->br_blockcount;
> + xfs_bmbt_set_blockcount(ep, temp);
> + if (delay) {
> + temp = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
> + da_old);
> + xfs_bmbt_set_startblock(ep, nullstartblock((int)temp));
> + trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);
> + da_new = temp;
> + break;
> + }
> + xfs_bmbt_set_startblock(ep, del_endblock);
> + trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);
> + break;
> +
> + case 1:
> + /*
> + * Deleting the last part of the extent.
> + */
> + temp = got.br_blockcount - del->br_blockcount;
> + trace_xfs_bmap_pre_update(ip, eidx, state, _THIS_IP_);
> + xfs_bmbt_set_blockcount(ep, temp);
> + if (delay) {
> + temp = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp),
> + da_old);
> + xfs_bmbt_set_startblock(ep, nullstartblock((int)temp));
> + trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);
> + da_new = temp;
> + break;
> + }
> + trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);
> + break;
> +
> + case 0:
> + /*
> + * Deleting the middle of the extent.
> + */
> + temp = del->br_startoff - got.br_startoff;
> + trace_xfs_bmap_pre_update(ip, eidx, state, _THIS_IP_);
> + xfs_bmbt_set_blockcount(ep, temp);
> + new.br_startoff = del_endoff;
> + temp2 = got_endoff - del_endoff;
> + new.br_blockcount = temp2;
> + new.br_state = got.br_state;
> + if (!delay) {
> + new.br_startblock = del_endblock;
> + } else {
> + temp = xfs_bmap_worst_indlen(ip, temp);
> + xfs_bmbt_set_startblock(ep, nullstartblock((int)temp));
> + temp2 = xfs_bmap_worst_indlen(ip, temp2);
> + new.br_startblock = nullstartblock((int)temp2);
> + da_new = temp + temp2;
> + while (da_new > da_old) {
> + if (temp) {
> + temp--;
> + da_new--;
> + xfs_bmbt_set_startblock(ep,
> + nullstartblock((int)temp));
> + }
> + if (da_new == da_old)
> + break;
> + if (temp2) {
> + temp2--;
> + da_new--;
> + new.br_startblock =
> + nullstartblock((int)temp2);
> + }
> + }
xfs_bmap_split_indlen() ?
Brian
> + }
> + trace_xfs_bmap_post_update(ip, eidx, state, _THIS_IP_);
> + xfs_iext_insert(ip, eidx + 1, 1, &new, state);
> + ++eidx;
> + break;
> + }
> +
> + /*
> + * Account for change in delayed indirect blocks.
> + * Nothing to do for disk quota accounting here.
> + */
> + ASSERT(da_old >= da_new);
> + if (da_old > da_new)
> + xfs_mod_fdblocks(mp, (int64_t)(da_old - da_new), false);
> +
> + return error;
> +}
> +
> +/*
> * Unmap (remove) blocks from a file.
> * If nexts is nonzero then the number of extents to remove is limited to
> * that value. If not all extents in the block range can be removed then
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index 75b1a1f..7c4ad01 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -221,6 +221,7 @@ int xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip,
> xfs_fileoff_t bno, xfs_filblks_t len, int flags,
> xfs_extnum_t nexts, xfs_fsblock_t *firstblock,
> struct xfs_defer_ops *dfops, int *done);
> +int xfs_bunmapi_cow(struct xfs_inode *ip, struct xfs_bmbt_irec *del);
> int xfs_check_nostate_extents(struct xfs_ifork *ifp, xfs_extnum_t idx,
> xfs_extnum_t num);
> uint xfs_default_attroffset(struct xfs_inode *ip);
>
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