On Fri, May 18, 2018 at 06:48:01PM +0200, Christoph Hellwig wrote:
> This way the implementation doesn't depend on buffer_head internals.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/iomap.c | 83 +++++++++++++++++++++++++++---------------------------
> 1 file changed, 42 insertions(+), 41 deletions(-)
>
> diff --git a/fs/iomap.c b/fs/iomap.c
> index bef5e91d40bf..0fecd5789d7b 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -594,31 +594,54 @@ EXPORT_SYMBOL_GPL(iomap_fiemap);
> *
> * Returns the offset within the file on success, and -ENOENT otherwise.
This comment is now wrong, since we return the offset via *lastoff and I
think the return value is whether or not we found what we were looking
for...?
> */
> -static loff_t
> -page_seek_hole_data(struct page *page, loff_t lastoff, int whence)
> +static bool
> +page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
> + int whence)
> {
> - loff_t offset = page_offset(page);
> - struct buffer_head *bh, *head;
> + const struct address_space_operations *ops = inode->i_mapping->a_ops;
> + unsigned int bsize = i_blocksize(inode), off;
> bool seek_data = whence == SEEK_DATA;
> + loff_t poff = page_offset(page);
>
> - if (lastoff < offset)
> - lastoff = offset;
> -
> - bh = head = page_buffers(page);
> - do {
> - offset += bh->b_size;
> - if (lastoff >= offset)
> - continue;
> + if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))
> + return false;
>
> + if (*lastoff < poff) {
> /*
> - * Any buffer with valid data in it should have BH_Uptodate set.
> + * Last offset smaller than the start of the page means we found
> + * a hole:
> */
> - if (buffer_uptodate(bh) == seek_data)
> - return lastoff;
> + if (whence == SEEK_HOLE)
> + return true;
> + *lastoff = poff;
> + }
>
> - lastoff = offset;
> - } while ((bh = bh->b_this_page) != head);
> - return -ENOENT;
> + /*
> + * Just check the page unless we can and should check block ranges:
> + */
> + if (bsize == PAGE_SIZE || !ops->is_partially_uptodate) {
> + if (PageUptodate(page) == seek_data)
> + return true;
> + return false;
return PageUptodate(page) == seek_data; ?
--D
> + }
> +
> + lock_page(page);
> + if (unlikely(page->mapping != inode->i_mapping))
> + goto out_unlock_not_found;
> +
> + for (off = 0; off < PAGE_SIZE; off += bsize) {
> + if ((*lastoff & ~PAGE_MASK) >= off + bsize)
> + continue;
> + if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
> + unlock_page(page);
> + return true;
> + }
> + *lastoff = poff + off + bsize;
> + }
> +
> +out_unlock_not_found:
> + unlock_page(page);
> + return false;
> }
>
> /*
> @@ -655,30 +678,8 @@ page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
> for (i = 0; i < nr_pages; i++) {
> struct page *page = pvec.pages[i];
>
> - /*
> - * At this point, the page may be truncated or
> - * invalidated (changing page->mapping to NULL), or
> - * even swizzled back from swapper_space to tmpfs file
> - * mapping. However, page->index will not change
> - * because we have a reference on the page.
> - *
> - * If current page offset is beyond where we've ended,
> - * we've found a hole.
> - */
> - if (whence == SEEK_HOLE &&
> - lastoff < page_offset(page))
> + if (page_seek_hole_data(inode, page, &lastoff, whence))
> goto check_range;
> -
> - lock_page(page);
> - if (likely(page->mapping == inode->i_mapping) &&
> - page_has_buffers(page)) {
> - lastoff = page_seek_hole_data(page, lastoff, whence);
> - if (lastoff >= 0) {
> - unlock_page(page);
> - goto check_range;
> - }
> - }
> - unlock_page(page);
> lastoff = page_offset(page) + PAGE_SIZE;
> }
> pagevec_release(&pvec);
> --
> 2.17.0
>
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