Commit 81d4782a authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

iomap: Simplify iomap_do_writepage() 



Rename end_offset to end_pos and offset_into_page to poff to match the
rest of the file.  Simplify the handling of the last page straddling
i_size by doing the EOF check based on the byte granularity i_size
instead of converting to a pgoff prematurely.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
parent 92655036

fs/iomap/buffered-io.c

+10 −13
Original line number Diff line number Diff line
@@ -1408,9 +1408,7 @@ 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;

	u64 end_pos, isize;



	trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE);
@@ -1441,11 +1439,9 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) 
	 * |     desired writeback range    |      see else    |

	 * ---------------------------------^------------------|

	 */

	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 {

	isize = i_size_read(inode);

	end_pos = page_offset(page) + PAGE_SIZE;

	if (end_pos > isize) {

		/*

		 * Check whether the page to write out is beyond or straddles

		 * i_size or not.
@@ -1457,7 +1453,8 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) 
		 * |				    |      Straddles     |

		 * ---------------------------------^-----------|--------|

		 */

		unsigned offset_into_page = offset & (PAGE_SIZE - 1);

		size_t poff = offset_in_page(isize);

		pgoff_t end_index = isize >> PAGE_SHIFT;



		/*

		 * Skip the page if it's fully outside i_size, e.g. due to a
@@ -1477,7 +1474,7 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) 
		 * offset is just equal to the EOF.

		 */

		if (page->index > end_index ||

		    (page->index == end_index && offset_into_page == 0))

		    (page->index == end_index && poff == 0))

			goto redirty;



		/*
@@ -1488,13 +1485,13 @@ 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, poff, PAGE_SIZE);



		/* Adjust the end_offset to the end of file */

		end_offset = offset;

		end_pos = isize;

	}



	return iomap_writepage_map(wpc, wbc, inode, page, end_offset);

	return iomap_writepage_map(wpc, wbc, inode, page, end_pos);



redirty:

	redirty_page_for_writepage(wbc, page);