Unverified Commit fb7a10ac authored by Joanne Koong's avatar Joanne Koong Committed by Christian Brauner
Browse files

iomap: set accurate iter->pos when reading folio ranges 



Advance iter to the correct position before calling an IO helper to read
in a folio range. This allows the helper to reliably use iter->pos to
determine the starting offset for reading.

This will simplify the interface for reading in folio ranges when iomap
read/readahead supports caller-provided callbacks.

Signed-off-by: default avatarJoanne Koong <joannelkoong@gmail.com>
Suggested-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent d43558ae

fs/iomap/buffered-io.c

+13 −8
Original line number Diff line number Diff line
@@ -375,10 +375,11 @@ static void iomap_bio_submit_read(struct iomap_read_folio_ctx *ctx) 
}



static void iomap_bio_read_folio_range(const struct iomap_iter *iter,

		struct iomap_read_folio_ctx *ctx, loff_t pos, size_t plen)

		struct iomap_read_folio_ctx *ctx, size_t plen)

{

	struct folio *folio = ctx->cur_folio;

	const struct iomap *iomap = &iter->iomap;

	loff_t pos = iter->pos;

	size_t poff = offset_in_folio(folio, pos);

	loff_t length = iomap_length(iter);

	sector_t sector;
@@ -506,7 +507,7 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, 
	loff_t length = iomap_length(iter);

	struct folio *folio = ctx->cur_folio;

	size_t poff, plen;

	loff_t count;

	loff_t pos_diff;

	int ret;



	if (iomap->type == IOMAP_INLINE) {
@@ -524,12 +525,16 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, 
		iomap_adjust_read_range(iter->inode, folio, &pos, length, &poff,

				&plen);



		count = pos - iter->pos + plen;

		if (WARN_ON_ONCE(count > length))

		pos_diff = pos - iter->pos;

		if (WARN_ON_ONCE(pos_diff + plen > length))

			return -EIO;



		ret = iomap_iter_advance(iter, pos_diff);

		if (ret)

			return ret;



		if (plen == 0)

			return iomap_iter_advance(iter, count);

			return 0;



		/* zero post-eof blocks as the page may be mapped */

		if (iomap_block_needs_zeroing(iter, pos)) {
@@ -539,13 +544,13 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, 
			if (!*bytes_pending)

				iomap_read_init(folio);

			*bytes_pending += plen;

			iomap_bio_read_folio_range(iter, ctx, pos, plen);

			iomap_bio_read_folio_range(iter, ctx, plen);

		}



		ret = iomap_iter_advance(iter, count);

		ret = iomap_iter_advance(iter, plen);

		if (ret)

			return ret;

		length -= count;

		length -= pos_diff + plen;

		pos = iter->pos;

	}

	return 0;