Unverified Commit c4f9a1ba authored by Brian Foster's avatar Brian Foster Committed by Christian Brauner
Browse files

iomap: helper to trim pos/bytes to within folio 



Several buffered write based iteration callbacks duplicate logic to
trim the current pos and length to within the current folio. Factor
this into a helper to make it easier to relocate closer to folio
lookup.

Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/20250506134118.911396-5-bfoster@redhat.com


Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 3ceb65b1

fs/iomap/buffered-io.c

+20 −15
Original line number Diff line number Diff line
@@ -766,6 +766,22 @@ static void __iomap_put_folio(struct iomap_iter *iter, size_t ret, 
	}

}



/* trim pos and bytes to within a given folio */

static loff_t iomap_trim_folio_range(struct iomap_iter *iter,

		struct folio *folio, size_t *offset, u64 *bytes)

{

	loff_t pos = iter->pos;

	size_t fsize = folio_size(folio);



	WARN_ON_ONCE(pos < folio_pos(folio));

	WARN_ON_ONCE(pos >= folio_pos(folio) + fsize);



	*offset = offset_in_folio(folio, pos);

	*bytes = min(*bytes, fsize - *offset);



	return pos;

}



static int iomap_write_begin_inline(const struct iomap_iter *iter,

		struct folio *folio)

{
@@ -920,7 +936,7 @@ static int iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) 
		struct folio *folio;

		loff_t old_size;

		size_t offset;		/* Offset into folio */

		size_t bytes;		/* Bytes to write to folio */

		u64 bytes;		/* Bytes to write to folio */

		size_t copied;		/* Bytes copied from user */

		u64 written;		/* Bytes have been written */

		loff_t pos;
@@ -959,11 +975,8 @@ static int iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) 
		}

		if (iter->iomap.flags & IOMAP_F_STALE)

			break;

		pos = iter->pos;



		offset = offset_in_folio(folio, pos);

		if (bytes > folio_size(folio) - offset)

			bytes = folio_size(folio) - offset;

		pos = iomap_trim_folio_range(iter, folio, &offset, &bytes);



		if (mapping_writably_mapped(mapping))

			flush_dcache_folio(folio);
@@ -1280,7 +1293,6 @@ static int iomap_unshare_iter(struct iomap_iter *iter) 
	do {

		struct folio *folio;

		size_t offset;

		loff_t pos;

		bool ret;



		bytes = min_t(u64, SIZE_MAX, bytes);
@@ -1289,11 +1301,8 @@ static int iomap_unshare_iter(struct iomap_iter *iter) 
			return status;

		if (iomap->flags & IOMAP_F_STALE)

			break;

		pos = iter->pos;



		offset = offset_in_folio(folio, pos);

		if (bytes > folio_size(folio) - offset)

			bytes = folio_size(folio) - offset;

		iomap_trim_folio_range(iter, folio, &offset, &bytes);



		ret = iomap_write_end(iter, bytes, bytes, folio);

		__iomap_put_folio(iter, bytes, folio);
@@ -1356,7 +1365,6 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero) 
	do {

		struct folio *folio;

		size_t offset;

		loff_t pos;

		bool ret;



		bytes = min_t(u64, SIZE_MAX, bytes);
@@ -1365,14 +1373,11 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero) 
			return status;

		if (iter->iomap.flags & IOMAP_F_STALE)

			break;

		pos = iter->pos;



		/* warn about zeroing folios beyond eof that won't write back */

		WARN_ON_ONCE(folio_pos(folio) > iter->inode->i_size);

		offset = offset_in_folio(folio, pos);

		if (bytes > folio_size(folio) - offset)

			bytes = folio_size(folio) - offset;



		iomap_trim_folio_range(iter, folio, &offset, &bytes);

		folio_zero_range(folio, offset, bytes);

		folio_mark_accessed(folio);