[PATCH v5 06/10] iomap: export iomap_iter_advance() and return remaining length

Brian Foster
2025-02-05T13:56:06Z

As a final step for generic iter advance, export the helper and
update it to return the remaining length of the current iteration
after the advance. This will usually be 0 in the iomap_iter() case,
but will be useful for the various operations that iterate on their
own and will be updated to advance as they progress.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/iomap/iter.c | 22 ++++++++--------------
include/linux/iomap.h | 1 +
2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c
index 8e0746ad80bd..cdba24dbbfd7 100644
--- a/fs/iomap/iter.c
+++ b/fs/iomap/iter.c
@@ -15,22 +15,16 @@ static inline void iomap_iter_reset_iomap(struct iomap_iter *iter)
}

/*
- * Advance to the next range we need to map.
- *
- * If the iomap is marked IOMAP_F_STALE, it means the existing map was not fully
- * processed - it was aborted because the extent the iomap spanned may have been
- * changed during the operation. In this case, the iteration behaviour is to
- * remap the unprocessed range of the iter, and that means we may need to remap
- * even when we've made no progress (i.e. count = 0). Hence the "finished
- * iterating" case needs to distinguish between (count = 0) meaning we are done
- * and (count = 0 && stale) meaning we need to remap the entire remaining range.
+ * Advance the current iterator position and return the length remaining for the
+ * current mapping.
*/
-static inline int iomap_iter_advance(struct iomap_iter *iter, s64 count)
+int iomap_iter_advance(struct iomap_iter *iter, u64 *count)
{
- if (WARN_ON_ONCE(count > iomap_length(iter)))
+ if (WARN_ON_ONCE(*count > iomap_length(iter)))
return -EIO;
- iter->pos += count;
- iter->len -= count;
+ iter->pos += *count;
+ iter->len -= *count;
+ *count = iomap_length(iter);
return 0;
}

@@ -93,7 +87,7 @@ int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
* 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);
+ ret = iomap_iter_advance(iter, &processed);
if (!ret && iter->len > 0)
ret = 1;
if (ret > 0 && !iter->processed && !stale)
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index f5ca71ac2fa2..f304c602e5fe 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -229,6 +229,7 @@ struct iomap_iter {
};

int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops);
+int iomap_iter_advance(struct iomap_iter *iter, u64 *count);

/**
* iomap_length_trim - trimmed length of the current iomap iteration
--
2.48.1