Unverified Commit 469739f1 authored by Brian Foster's avatar Brian Foster Committed by Christian Brauner
Browse files

iomap: remove unnecessary advance from iomap_iter() 



At this point, all iomap operations have been updated to advance the
iomap_iter directly before returning to iomap_iter(). Therefore, the
complexity of handling both the old and new semantics is no longer
required and can be removed from iomap_iter().

Update iomap_iter() to expect success or failure status in
iter.processed. As a precaution and developer hint to prevent
inadvertent use of old semantics, warn on a positive return code and
fail the operation. Remove the unnecessary advance and simplify the
termination logic.

Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250224144757.237706-11-bfoster@redhat.com


Reviewed-by: default avatar"Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 6fe32fe1

fs/iomap/iter.c

+15 −24
Original line number Diff line number Diff line
@@ -60,9 +60,8 @@ static inline void iomap_iter_done(struct iomap_iter *iter) 
int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)

{

	bool stale = iter->iomap.flags & IOMAP_F_STALE;

	ssize_t advanced = iter->processed > 0 ? iter->processed : 0;

	u64 olen = iter->len;

	s64 processed;

	ssize_t advanced;

	u64 olen;

	int ret;



	trace_iomap_iter(iter, ops, _RET_IP_);
@@ -71,14 +70,11 @@ int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops) 
		goto begin;



	/*

	 * If iter.processed is zero, the op may still have advanced the iter

	 * itself. Calculate the advanced and original length bytes based on how

	 * far pos has advanced for ->iomap_end().

	 * Calculate how far the iter was advanced and the original length bytes

	 * for ->iomap_end().

	 */

	if (!advanced) {

	advanced = iter->pos - iter->iter_start_pos;

		olen += advanced;

	}

	olen = iter->len + advanced;



	if (ops->iomap_end) {

		ret = ops->iomap_end(iter->inode, iter->iter_start_pos,
@@ -89,27 +85,22 @@ int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops) 
			return ret;

	}



	processed = iter->processed;

	if (processed < 0) {

		iomap_iter_reset_iomap(iter);

		return processed;

	}

	/* detect old return semantics where this would advance */

	if (WARN_ON_ONCE(iter->processed > 0))

		iter->processed = -EIO;



	/*

	 * Advance the iter and clear state from the previous iteration. This

	 * passes iter->processed because that reflects the bytes processed but

	 * not yet advanced by the iter handler.

	 *

	 * Use iter->len to determine whether to continue onto the next mapping.

	 * Explicitly terminate in the case where the current iter has not

	 * Explicitly terminate on error status or if the current iter has not

	 * advanced at all (i.e. no work was done for some reason) unless the

	 * mapping has been marked stale and needs to be reprocessed.

	 */

	ret = iomap_iter_advance(iter, &processed);

	if (!ret && iter->len > 0)

		ret = 1;

	if (ret > 0 && !advanced && !stale)

	if (iter->processed < 0)

		ret = iter->processed;

	else if (iter->len == 0 || (!advanced && !stale))

		ret = 0;

	else

		ret = 1;

	iomap_iter_reset_iomap(iter);

	if (ret <= 0)

		return ret;