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Subject[PATCH v2 7/9] iomap: Convert write_count to write_bytes_pending
Date
Instead of counting bio segments, count the number of bytes submitted.
This insulates us from the block layer's definition of what a 'same page'
is, which is not necessarily clear once THPs are involved.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/iomap/buffered-io.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 1cf976a8e55c..64a5cb383f30 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -27,7 +27,7 @@
*/
struct iomap_page {
atomic_t read_bytes_pending;
- atomic_t write_count;
+ atomic_t write_bytes_pending;
spinlock_t uptodate_lock;
unsigned long uptodate[];
};
@@ -73,7 +73,7 @@ iomap_page_release(struct page *page)
if (!iop)
return;
WARN_ON_ONCE(atomic_read(&iop->read_bytes_pending));
- WARN_ON_ONCE(atomic_read(&iop->write_count));
+ WARN_ON_ONCE(atomic_read(&iop->write_bytes_pending));
WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) !=
PageUptodate(page));
kfree(iop);
@@ -1047,7 +1047,7 @@ EXPORT_SYMBOL_GPL(iomap_page_mkwrite);

static void
iomap_finish_page_writeback(struct inode *inode, struct page *page,
- int error)
+ int error, unsigned int len)
{
struct iomap_page *iop = to_iomap_page(page);

@@ -1057,9 +1057,9 @@ iomap_finish_page_writeback(struct inode *inode, struct page *page,
}

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

- if (!iop || atomic_dec_and_test(&iop->write_count))
+ if (!iop || atomic_sub_and_test(len, &iop->write_bytes_pending))
end_page_writeback(page);
}

@@ -1093,7 +1093,8 @@ iomap_finish_ioend(struct iomap_ioend *ioend, int error)

/* walk each page on bio, ending page IO on them */
bio_for_each_segment_all(bv, bio, iter_all)
- iomap_finish_page_writeback(inode, bv->bv_page, error);
+ iomap_finish_page_writeback(inode, bv->bv_page, error,
+ bv->bv_len);
bio_put(bio);
}
/* The ioend has been freed by bio_put() */
@@ -1309,8 +1310,8 @@ iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page,

merged = __bio_try_merge_page(wpc->ioend->io_bio, page, len, poff,
&same_page);
- if (iop && !same_page)
- atomic_inc(&iop->write_count);
+ if (iop)
+ atomic_add(len, &iop->write_bytes_pending);

if (!merged) {
if (bio_full(wpc->ioend->io_bio, len)) {
@@ -1353,7 +1354,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
LIST_HEAD(submit_list);

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

/*
* Walk through the page to find areas to write back. If we run off the
--
2.28.0
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