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    Subject[PATCH v4 16/36] iomap: Support large pages in write paths
    Date
    From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

    Use thp_size() instead of PAGE_SIZE and offset_in_thp() instead of
    offset_in_page(). Also simplify the logic in iomap_do_writepage()
    for determining end of file.

    Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
    ---
    fs/iomap/buffered-io.c | 52 +++++++++++++++++++++++-------------------
    1 file changed, 29 insertions(+), 23 deletions(-)

    diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
    index 75f42c0d4cd9..b7504b8aa90c 100644
    --- a/fs/iomap/buffered-io.c
    +++ b/fs/iomap/buffered-io.c
    @@ -466,7 +466,7 @@ iomap_is_partially_uptodate(struct page *page, unsigned long from,
    unsigned i;

    /* Limit range to one page */
    - len = min_t(unsigned, PAGE_SIZE - from, count);
    + len = min_t(unsigned, thp_size(page) - from, count);

    /* First and last blocks in range within page */
    first = from >> inode->i_blkbits;
    @@ -510,7 +510,7 @@ iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
    * If we are invalidating the entire page, clear the dirty state from it
    * and release it to avoid unnecessary buildup of the LRU.
    */
    - if (offset == 0 && len == PAGE_SIZE) {
    + if (offset == 0 && len == thp_size(page)) {
    WARN_ON_ONCE(PageWriteback(page));
    cancel_dirty_page(page);
    iomap_page_release(page);
    @@ -586,7 +586,9 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
    loff_t block_size = i_blocksize(inode);
    loff_t block_start = pos & ~(block_size - 1);
    loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
    - unsigned from = offset_in_page(pos), to = from + len, poff, plen;
    + unsigned from = offset_in_thp(page, pos);
    + unsigned to = from + len;
    + unsigned poff, plen;
    int status;

    if (PageUptodate(page))
    @@ -654,8 +656,8 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
    else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
    status = __block_write_begin_int(page, pos, len, NULL, srcmap);
    else
    - status = __iomap_write_begin(inode, pos, len, flags, page,
    - srcmap);
    + status = __iomap_write_begin(inode, pos, len, flags,
    + compound_head(page), srcmap);

    if (unlikely(status))
    goto out_unlock;
    @@ -718,7 +720,7 @@ __iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
    */
    if (unlikely(copied < len && !PageUptodate(page)))
    return 0;
    - iomap_set_range_uptodate(page, offset_in_page(pos), len);
    + iomap_set_range_uptodate(page, offset_in_thp(page, pos), len);
    iomap_set_page_dirty(page);
    return copied;
    }
    @@ -754,7 +756,8 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len, unsigned copied,
    ret = block_write_end(NULL, inode->i_mapping, pos, len, copied,
    page, NULL);
    } else {
    - ret = __iomap_write_end(inode, pos, len, copied, page);
    + ret = __iomap_write_end(inode, pos, len, copied,
    + compound_head(page));
    }

    /*
    @@ -793,6 +796,10 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
    unsigned long bytes; /* Bytes to write to page */
    size_t copied; /* Bytes copied from user */

    + /*
    + * XXX: We don't know what size page we'll find in the
    + * page cache, so only copy up to a regular page boundary.
    + */
    offset = offset_in_page(pos);
    bytes = min_t(unsigned long, PAGE_SIZE - offset,
    iov_iter_count(i));
    @@ -1129,7 +1136,7 @@ iomap_finish_ioend(struct iomap_ioend *ioend, int error)
    next = bio->bi_private;

    /* walk each page on bio, ending page IO on them */
    - bio_for_each_segment_all(bv, bio, iter_all)
    + bio_for_each_thp_segment_all(bv, bio, iter_all)
    iomap_finish_page_writeback(inode, bv->bv_page, error);
    bio_put(bio);
    }
    @@ -1335,7 +1342,7 @@ iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page,
    {
    sector_t sector = iomap_sector(&wpc->iomap, offset);
    unsigned len = i_blocksize(inode);
    - unsigned poff = offset & (PAGE_SIZE - 1);
    + unsigned poff = offset & (thp_size(page) - 1);
    bool merged, same_page = false;

    if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, offset, sector)) {
    @@ -1385,11 +1392,12 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
    struct iomap_page *iop = to_iomap_page(page);
    struct iomap_ioend *ioend, *next;
    unsigned len = i_blocksize(inode);
    - u64 file_offset; /* file offset of page */
    + loff_t pos;
    int error = 0, count = 0, i;
    + int nr_blocks = i_blocks_per_page(inode, page);
    LIST_HEAD(submit_list);

    - WARN_ON_ONCE(i_blocks_per_page(inode, page) > 1 && !iop);
    + WARN_ON_ONCE(nr_blocks > 1 && !iop);
    WARN_ON_ONCE(iop && atomic_read(&iop->write_count) != 0);

    /*
    @@ -1397,20 +1405,20 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
    * end of the current map or find the current map invalid, grab a new
    * one.
    */
    - for (i = 0, file_offset = page_offset(page);
    - i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
    - i++, file_offset += len) {
    + for (i = 0, pos = page_offset(page);
    + i < nr_blocks && pos < end_offset;
    + i++, pos += len) {
    if (iop && !test_bit(i, iop->uptodate))
    continue;

    - error = wpc->ops->map_blocks(wpc, inode, file_offset);
    + error = wpc->ops->map_blocks(wpc, inode, pos);
    if (error)
    break;
    if (WARN_ON_ONCE(wpc->iomap.type == IOMAP_INLINE))
    continue;
    if (wpc->iomap.type == IOMAP_HOLE)
    continue;
    - iomap_add_to_ioend(inode, file_offset, page, iop, wpc, wbc,
    + iomap_add_to_ioend(inode, pos, page, iop, wpc, wbc,
    &submit_list);
    count++;
    }
    @@ -1492,7 +1500,6 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
    {
    struct iomap_writepage_ctx *wpc = data;
    struct inode *inode = page->mapping->host;
    - pgoff_t end_index;
    u64 end_offset;
    loff_t offset;

    @@ -1533,10 +1540,8 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
    * ---------------------------------^------------------|
    */
    offset = i_size_read(inode);
    - end_index = offset >> PAGE_SHIFT;
    - if (page->index < end_index)
    - end_offset = (loff_t)(page->index + 1) << PAGE_SHIFT;
    - else {
    + end_offset = page_offset(page) + thp_size(page);
    + if (end_offset > offset) {
    /*
    * Check whether the page to write out is beyond or straddles
    * i_size or not.
    @@ -1548,7 +1553,8 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
    * | | Straddles |
    * ---------------------------------^-----------|--------|
    */
    - unsigned offset_into_page = offset & (PAGE_SIZE - 1);
    + unsigned offset_into_page = offset_in_thp(page, offset);
    + pgoff_t end_index = offset >> PAGE_SHIFT;

    /*
    * Skip the page if it is fully outside i_size, e.g. due to a
    @@ -1579,7 +1585,7 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
    * memory is zeroed when mapped, and writes to that region are
    * not written out to the file."
    */
    - zero_user_segment(page, offset_into_page, PAGE_SIZE);
    + zero_user_segment(page, offset_into_page, thp_size(page));

    /* Adjust the end_offset to the end of file */
    end_offset = offset;
    --
    2.26.2
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