Re: [PATCH v2 20/28] iomap: Convert iomap_write_begin() and iomap_write_end() to folios
From: "Darrick J. Wong" <djwong@kernel.org>
Date: 2021-11-17 04:31:29
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linux-fsdevel, linux-xfs, lkml
On Mon, Nov 08, 2021 at 04:05:43AM +0000, Matthew Wilcox (Oracle) wrote:
quoted hunk ↗ jump to hunk
These functions still only work in PAGE_SIZE chunks, but there are fewer conversions from tail to head pages as a result of this patch. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> --- fs/iomap/buffered-io.c | 66 ++++++++++++++++++++---------------------- 1 file changed, 31 insertions(+), 35 deletions(-)diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 9c61d12028ca..f4ae200adc4c 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c
<snip>
quoted hunk ↗ jump to hunk
@@ -741,6 +737,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) long status = 0; do { + struct folio *folio; struct page *page; unsigned long offset; /* Offset into pagecache page */ unsigned long bytes; /* Bytes to write to page */@@ -764,16 +761,17 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) break; } - status = iomap_write_begin(iter, pos, bytes, &page); + status = iomap_write_begin(iter, pos, bytes, &folio); if (unlikely(status)) break; + page = folio_file_page(folio, pos >> PAGE_SHIFT); if (mapping_writably_mapped(iter->inode->i_mapping)) flush_dcache_page(page); copied = copy_page_from_iter_atomic(page, offset, bytes, i);
Hrmm. In principle (or I guess even a subsequent patch), if we had multi-page folios, could we simply loop the pages in the folio instead of doing a single page and then calling back into iomap_write_begin to get (probably) the same folio? This looks like a fairly straightforward conversion, but I was wondering about that one little point... Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D
quoted hunk ↗ jump to hunk
- status = iomap_write_end(iter, pos, bytes, copied, page); + status = iomap_write_end(iter, pos, bytes, copied, folio); if (unlikely(copied != status)) iov_iter_revert(i, copied - status);@@ -839,13 +837,13 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter) do { unsigned long offset = offset_in_page(pos); unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length); - struct page *page; + struct folio *folio; - status = iomap_write_begin(iter, pos, bytes, &page); + status = iomap_write_begin(iter, pos, bytes, &folio); if (unlikely(status)) return status; - status = iomap_write_end(iter, pos, bytes, bytes, page); + status = iomap_write_end(iter, pos, bytes, bytes, folio); if (WARN_ON_ONCE(status == 0)) return -EIO;@@ -882,21 +880,19 @@ EXPORT_SYMBOL_GPL(iomap_file_unshare); static s64 __iomap_zero_iter(struct iomap_iter *iter, loff_t pos, u64 length) { struct folio *folio; - struct page *page; int status; size_t offset, bytes; - status = iomap_write_begin(iter, pos, length, &page); + status = iomap_write_begin(iter, pos, length, &folio); if (status) return status; - folio = page_folio(page); offset = offset_in_folio(folio, pos); bytes = min_t(u64, folio_size(folio) - offset, length); folio_zero_range(folio, offset, bytes); folio_mark_accessed(folio); - return iomap_write_end(iter, pos, bytes, bytes, page); + return iomap_write_end(iter, pos, bytes, bytes, folio); } static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)-- 2.33.0