Merge patch series "iomap: incremental advance conversion -- phase 2"

Brian Foster <bfoster@redhat.com> says:

Here's phase 2 of the incremental iter advance conversions. This updates
all remaining iomap operations to advance the iter within the operation
and thus removes the need to advance from the core iomap iterator. Once
all operations are switched over, the core advance code is removed and
the processed field is renamed to reflect that it is now a pure status
code.

For context, this was first introduced in a previous series [1] that
focused mainly on the core mechanism and iomap buffered write. This is
because original impetus was to facilitate a folio batch mechanism where
a filesystem can optionally provide a batch of folios to process for a
given mapping (i.e. zero range of an unwritten mapping with dirty folios
in pagecache). That is still WIP, but the broader point is that this was
originally intended as an optional mode until consensus that fell out of
discussion was that it would be preferable to convert over everything.
This presumably facilitates some other future work and simplifies
semantics in the core iteration code.

Patches 1-3 convert over iomap buffered read, direct I/O and various
other remaining ops (swap, etc.). Patches 4-9 convert over the various
DAX iomap operations. Finally, patches 10-12 introduce some cleanups now
that all iomap operations have updated iteration semantics.

* patches from https://lore.kernel.org/r/20250224144757.237706-1-bfoster@redhat.com:
  iomap: introduce a full map advance helper
  iomap: rename iomap_iter processed field to status
  iomap: remove unnecessary advance from iomap_iter()
  dax: advance the iomap_iter on pte and pmd faults
  dax: advance the iomap_iter on dedupe range
  dax: advance the iomap_iter on unshare range
  dax: advance the iomap_iter on zero range
  dax: push advance down into dax_iomap_iter() for read and write
  dax: advance the iomap_iter in the read/write path
  iomap: convert misc simple ops to incremental advance
  iomap: advance the iter on direct I/O
  iomap: advance the iter directly on buffered read

Link: https://lore.kernel.org/r/20250224144757.237706-1-bfoster@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index e180dacf434c..1fd66bc29cc1 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -220,9 +220,8 @@ struct iomap_ops {
  *	It is updated at the same time as @pos.
  * @iter_start_pos: The original start pos for the current iomap. Used for
  *	incremental iter advance.
- * @processed: The number of bytes the most recent iteration needs iomap_iter()
- *	to advance the iter, zero if the iter was already advanced, or a
- *	negative errno for an error during the operation.
+ * @status: Status of the most recent iteration. Zero on success or a negative
+ *	errno on error.
  * @flags: Zero or more of the iomap_begin flags above.
  * @iomap: Map describing the I/O iteration
  * @srcmap: Source map for COW operations
@@ -232,7 +231,7 @@ struct iomap_iter {
 	loff_t pos;
 	u64 len;
 	loff_t iter_start_pos;
-	s64 processed;
+	int status;
 	unsigned flags;
 	struct iomap iomap;
 	struct iomap srcmap;
@@ -273,6 +272,16 @@ static inline u64 iomap_length(const struct iomap_iter *iter)
 }
 
 /**
+ * iomap_iter_advance_full - advance by the full length of current map
+ */
+static inline int iomap_iter_advance_full(struct iomap_iter *iter)
+{
+	u64 length = iomap_length(iter);
+
+	return iomap_iter_advance(iter, &length);
+}
+
+/**
  * iomap_iter_srcmap - return the source map for the current iomap iteration
  * @i: iteration structure
  *