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iomap: remove unnecessary advance from iomap_iter()

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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: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250224144757.237706-11-bfoster@redhat.com
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Brian Foster
2025-02-24 09:47:55 -05:00
committed by Christian Brauner
parent 6fe32fe1bb
commit 469739f1d8
1 changed files with 15 additions and 24 deletions
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39
fs/iomap/iter.c
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@@ -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;
}
advanced = iter->pos - iter->iter_start_pos;
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;