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Subject[PATCH v3 21/25] iomap: Simplify iomap_do_writepage()
Date
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: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
fs/iomap/buffered-io.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 20e7087aa75c..8bfdda8e5f1c 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -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);
--
2.33.0
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