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Subject[PATCH v3 15/25] iomap: Allow iomap_write_begin() to be called with the full length
Date
In the future, we want write_begin to know the entire length of the
write so that it can choose to allocate large folios. Pass the full
length in from __iomap_zero_iter() and limit it where necessary.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/iomap/buffered-io.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 8d7a67655b60..b1ded5204d1c 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -619,6 +619,9 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
if (fatal_signal_pending(current))
return -EINTR;

+ if (!mapping_large_folio_support(iter->inode->i_mapping))
+ len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));
+
if (page_ops && page_ops->page_prepare) {
status = page_ops->page_prepare(iter->inode, pos, len);
if (status)
@@ -632,6 +635,8 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
goto out_no_page;
}
folio = page_folio(page);
+ if (pos + len > folio_pos(folio) + folio_size(folio))
+ len = folio_pos(folio) + folio_size(folio) - pos;

if (srcmap->type == IOMAP_INLINE)
status = iomap_write_begin_inline(iter, page);
@@ -891,11 +896,13 @@ static s64 __iomap_zero_iter(struct iomap_iter *iter, loff_t pos, u64 length)
struct page *page;
int status;
unsigned offset = offset_in_page(pos);
- unsigned bytes = min_t(u64, PAGE_SIZE - offset, length);
+ unsigned bytes = min_t(u64, UINT_MAX, length);

status = iomap_write_begin(iter, pos, bytes, &page);
if (status)
return status;
+ if (bytes > PAGE_SIZE - offset)
+ bytes = PAGE_SIZE - offset;

zero_user(page, offset, bytes);
mark_page_accessed(page);
--
2.33.0
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