Re: [PATCH 06/12] xfs: remove the fork fields in the writepage_ctx and ioend

Darrick J. Wong
2019-10-15T18:05:31Z

On Tue, Oct 15, 2019 at 05:43:39PM +0200, Christoph Hellwig wrote:
> In preparation for moving the writeback code to iomap.c, replace the
> XFS-specific COW fork concept with the iomap IOMAP_F_SHARED flag.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

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

--D

> ---
> fs/xfs/xfs_aops.c | 71 ++++++++++++++++++++++++++++++-----------------
> fs/xfs/xfs_aops.h | 2 +-
> 2 files changed, 46 insertions(+), 27 deletions(-)
>
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index df5955388adc..00fe40b35f72 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -23,7 +23,6 @@
> */
> struct xfs_writepage_ctx {
> struct iomap iomap;
> - int fork;
> unsigned int data_seq;
> unsigned int cow_seq;
> struct xfs_ioend *ioend;
> @@ -272,7 +271,7 @@ xfs_end_ioend(
> */
> error = blk_status_to_errno(ioend->io_bio->bi_status);
> if (unlikely(error)) {
> - if (ioend->io_fork == XFS_COW_FORK)
> + if (ioend->io_flags & IOMAP_F_SHARED)
> xfs_reflink_cancel_cow_range(ip, offset, size, true);
> goto done;
> }
> @@ -280,7 +279,7 @@ xfs_end_ioend(
> /*
> * Success: commit the COW or unwritten blocks if needed.
> */
> - if (ioend->io_fork == XFS_COW_FORK)
> + if (ioend->io_flags & IOMAP_F_SHARED)
> error = xfs_reflink_end_cow(ip, offset, size);
> else if (ioend->io_type == IOMAP_UNWRITTEN)
> error = xfs_iomap_write_unwritten(ip, offset, size, false);
> @@ -304,7 +303,8 @@ xfs_ioend_can_merge(
> {
> if (ioend->io_bio->bi_status != next->io_bio->bi_status)
> return false;
> - if ((ioend->io_fork == XFS_COW_FORK) ^ (next->io_fork == XFS_COW_FORK))
> + if ((ioend->io_flags & IOMAP_F_SHARED) ^
> + (next->io_flags & IOMAP_F_SHARED))
> return false;
> if ((ioend->io_type == IOMAP_UNWRITTEN) ^
> (next->io_type == IOMAP_UNWRITTEN))
> @@ -404,6 +404,13 @@ xfs_end_io(
> }
> }
>
> +static inline bool xfs_ioend_needs_workqueue(struct xfs_ioend *ioend)
> +{
> + return ioend->io_private ||
> + ioend->io_type == IOMAP_UNWRITTEN ||
> + (ioend->io_flags & IOMAP_F_SHARED);
> +}
> +
> STATIC void
> xfs_end_bio(
> struct bio *bio)
> @@ -413,9 +420,7 @@ xfs_end_bio(
> struct xfs_mount *mp = ip->i_mount;
> unsigned long flags;
>
> - if (ioend->io_fork == XFS_COW_FORK ||
> - ioend->io_type == IOMAP_UNWRITTEN ||
> - ioend->io_private) {
> + if (xfs_ioend_needs_workqueue(ioend)) {
> spin_lock_irqsave(&ip->i_ioend_lock, flags);
> if (list_empty(&ip->i_ioend_list))
> WARN_ON_ONCE(!queue_work(mp->m_unwritten_workqueue,
> @@ -444,7 +449,7 @@ xfs_imap_valid(
> * covers the offset. Be careful to check this first because the caller
> * can revalidate a COW mapping without updating the data seqno.
> */
> - if (wpc->fork == XFS_COW_FORK)
> + if (wpc->iomap.flags & IOMAP_F_SHARED)
> return true;
>
> /*
> @@ -474,6 +479,7 @@ static int
> xfs_convert_blocks(
> struct xfs_writepage_ctx *wpc,
> struct xfs_inode *ip,
> + int whichfork,
> loff_t offset)
> {
> int error;
> @@ -485,8 +491,8 @@ xfs_convert_blocks(
> * delalloc extent if free space is sufficiently fragmented.
> */
> do {
> - error = xfs_bmapi_convert_delalloc(ip, wpc->fork, offset,
> - &wpc->iomap, wpc->fork == XFS_COW_FORK ?
> + error = xfs_bmapi_convert_delalloc(ip, whichfork, offset,
> + &wpc->iomap, whichfork == XFS_COW_FORK ?
> &wpc->cow_seq : &wpc->data_seq);
> if (error)
> return error;
> @@ -507,6 +513,7 @@ xfs_map_blocks(
> xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
> xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
> xfs_fileoff_t cow_fsb = NULLFILEOFF;
> + int whichfork = XFS_DATA_FORK;
> struct xfs_bmbt_irec imap;
> struct xfs_iext_cursor icur;
> int retries = 0;
> @@ -555,7 +562,7 @@ xfs_map_blocks(
> wpc->cow_seq = READ_ONCE(ip->i_cowfp->if_seq);
> xfs_iunlock(ip, XFS_ILOCK_SHARED);
>
> - wpc->fork = XFS_COW_FORK;
> + whichfork = XFS_COW_FORK;
> goto allocate_blocks;
> }
>
> @@ -578,8 +585,6 @@ xfs_map_blocks(
> wpc->data_seq = READ_ONCE(ip->i_df.if_seq);
> xfs_iunlock(ip, XFS_ILOCK_SHARED);
>
> - wpc->fork = XFS_DATA_FORK;
> -
> /* landed in a hole or beyond EOF? */
> if (imap.br_startoff > offset_fsb) {
> imap.br_blockcount = imap.br_startoff - offset_fsb;
> @@ -604,10 +609,10 @@ xfs_map_blocks(
> goto allocate_blocks;
>
> xfs_bmbt_to_iomap(ip, &wpc->iomap, &imap, 0);
> - trace_xfs_map_blocks_found(ip, offset, count, wpc->fork, &imap);
> + trace_xfs_map_blocks_found(ip, offset, count, whichfork, &imap);
> return 0;
> allocate_blocks:
> - error = xfs_convert_blocks(wpc, ip, offset);
> + error = xfs_convert_blocks(wpc, ip, whichfork, offset);
> if (error) {
> /*
> * If we failed to find the extent in the COW fork we might have
> @@ -616,7 +621,7 @@ xfs_map_blocks(
> * the former case, but prevent additional retries to avoid
> * looping forever for the latter case.
> */
> - if (error == -EAGAIN && wpc->fork == XFS_COW_FORK && !retries++)
> + if (error == -EAGAIN && whichfork == XFS_COW_FORK && !retries++)
> goto retry;
> ASSERT(error != -EAGAIN);
> return error;
> @@ -627,7 +632,7 @@ xfs_map_blocks(
> * original delalloc one. Trim the return extent to the next COW
> * boundary again to force a re-lookup.
> */
> - if (wpc->fork != XFS_COW_FORK && cow_fsb != NULLFILEOFF) {
> + if (whichfork != XFS_COW_FORK && cow_fsb != NULLFILEOFF) {
> loff_t cow_offset = XFS_FSB_TO_B(mp, cow_fsb);
>
> if (cow_offset < wpc->iomap.offset + wpc->iomap.length)
> @@ -636,7 +641,7 @@ xfs_map_blocks(
>
> ASSERT(wpc->iomap.offset <= offset);
> ASSERT(wpc->iomap.offset + wpc->iomap.length > offset);
> - trace_xfs_map_blocks_alloc(ip, offset, count, wpc->fork, &imap);
> + trace_xfs_map_blocks_alloc(ip, offset, count, whichfork, &imap);
> return 0;
> }
>
> @@ -670,14 +675,14 @@ xfs_submit_ioend(
> nofs_flag = memalloc_nofs_save();
>
> /* Convert CoW extents to regular */
> - if (!status && ioend->io_fork == XFS_COW_FORK) {
> + if (!status && (ioend->io_flags & IOMAP_F_SHARED)) {
> status = xfs_reflink_convert_cow(XFS_I(ioend->io_inode),
> ioend->io_offset, ioend->io_size);
> }
>
> /* Reserve log space if we might write beyond the on-disk inode size. */
> if (!status &&
> - (ioend->io_fork == XFS_COW_FORK ||
> + ((ioend->io_flags & IOMAP_F_SHARED) ||
> ioend->io_type != IOMAP_UNWRITTEN) &&
> xfs_ioend_is_append(ioend) &&
> !ioend->io_private)
> @@ -724,8 +729,8 @@ xfs_alloc_ioend(
>
> ioend = container_of(bio, struct xfs_ioend, io_inline_bio);
> INIT_LIST_HEAD(&ioend->io_list);
> - ioend->io_fork = wpc->fork;
> ioend->io_type = wpc->iomap.type;
> + ioend->io_flags = wpc->iomap.flags;
> ioend->io_inode = inode;
> ioend->io_size = 0;
> ioend->io_offset = offset;
> @@ -759,6 +764,24 @@ xfs_chain_bio(
> return new;
> }
>
> +static bool
> +xfs_can_add_to_ioend(
> + struct xfs_writepage_ctx *wpc,
> + xfs_off_t offset,
> + sector_t sector)
> +{
> + if ((wpc->iomap.flags & IOMAP_F_SHARED) !=
> + (wpc->ioend->io_flags & IOMAP_F_SHARED))
> + return false;
> + if (wpc->iomap.type != wpc->ioend->io_type)
> + return false;
> + if (offset != wpc->ioend->io_offset + wpc->ioend->io_size)
> + return false;
> + if (sector != bio_end_sector(wpc->ioend->io_bio))
> + return false;
> + return true;
> +}
> +
> /*
> * Test to see if we have an existing ioend structure that we could append to
> * first, otherwise finish off the current ioend and start another.
> @@ -778,11 +801,7 @@ xfs_add_to_ioend(
> unsigned poff = offset & (PAGE_SIZE - 1);
> bool merged, same_page = false;
>
> - if (!wpc->ioend ||
> - wpc->fork != wpc->ioend->io_fork ||
> - wpc->iomap.type != wpc->ioend->io_type ||
> - sector != bio_end_sector(wpc->ioend->io_bio) ||
> - offset != wpc->ioend->io_offset + wpc->ioend->io_size) {
> + if (!wpc->ioend || !xfs_can_add_to_ioend(wpc, offset, sector)) {
> if (wpc->ioend)
> list_add(&wpc->ioend->io_list, iolist);
> wpc->ioend = xfs_alloc_ioend(inode, wpc, offset, sector, wbc);
> diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h
> index 6a45d675dcba..4a0226cdad4f 100644
> --- a/fs/xfs/xfs_aops.h
> +++ b/fs/xfs/xfs_aops.h
> @@ -13,8 +13,8 @@ extern struct bio_set xfs_ioend_bioset;
> */
> struct xfs_ioend {
> struct list_head io_list; /* next ioend in chain */
> - int io_fork; /* inode fork written back */
> u16 io_type;
> + u16 io_flags; /* IOMAP_F_* */
> struct inode *io_inode; /* file being written to */
> size_t io_size; /* size of the extent */
> xfs_off_t io_offset; /* offset in the file */
> --
> 2.20.1
>