[PATCH 11/14] iomap: factor out a iomap_writepage_map_block helper

Christoph Hellwig
2023-12-07T07:27:54Z

Split the loop body that calls into the file system to map a block and
add it to the ioend into a separate helper to prefer for refactoring of
the surrounding code.

Note that this was the only place in iomap_writepage_map that could
return an error, so include the call to ->discard_folio into the new
helper as that will help to avoid code duplication in the future.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
fs/iomap/buffered-io.c | 70 ++++++++++++++++++++++++++----------------
1 file changed, 43 insertions(+), 27 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 21f5019c0fe762..622764ed649d57 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1722,6 +1722,45 @@ static void iomap_add_to_ioend(struct iomap_writepage_ctx *wpc,
wbc_account_cgroup_owner(wbc, &folio->page, len);
}

+static int iomap_writepage_map_blocks(struct iomap_writepage_ctx *wpc,
+ struct writeback_control *wbc, struct folio *folio,
+ struct inode *inode, u64 pos, unsigned *count,
+ struct list_head *submit_list)
+{
+ int error;
+
+ error = wpc->ops->map_blocks(wpc, inode, pos);
+ if (error)
+ goto fail;
+ trace_iomap_writepage_map(inode, &wpc->iomap);
+
+ switch (wpc->iomap.type) {
+ case IOMAP_INLINE:
+ WARN_ON_ONCE(1);
+ error = -EIO;
+ break;
+ case IOMAP_HOLE:
+ break;
+ default:
+ iomap_add_to_ioend(wpc, wbc, folio, inode, pos, submit_list);
+ (*count)++;
+ }
+
+fail:
+ /*
+ * We cannot cancel the ioend directly here on error. We may have
+ * already set other pages under writeback and hence we have to run I/O
+ * completion to mark the error state of the pages under writeback
+ * appropriately.
+ *
+ * Just let the file system know what portion of the folio failed to
+ * map.
+ */
+ if (error && wpc->ops->discard_folio)
+ wpc->ops->discard_folio(folio, pos);
+ return error;
+}
+
/*
* Check interaction of the folio with the file end.
*
@@ -1806,7 +1845,8 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
unsigned nblocks = i_blocks_per_folio(inode, folio);
u64 pos = folio_pos(folio);
u64 end_pos = pos + folio_size(folio);
- int error = 0, count = 0, i;
+ unsigned count = 0;
+ int error = 0, i;
LIST_HEAD(submit_list);

trace_iomap_writepage(inode, pos, folio_size(folio));
@@ -1832,19 +1872,10 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
for (i = 0; i < nblocks && pos < end_pos; i++, pos += len) {
if (ifs && !ifs_block_is_dirty(folio, ifs, i))
continue;
-
- error = wpc->ops->map_blocks(wpc, inode, pos);
+ error = iomap_writepage_map_blocks(wpc, wbc, folio, inode, pos,
+ &count, &submit_list);
if (error)
break;
- trace_iomap_writepage_map(inode, &wpc->iomap);
- if (WARN_ON_ONCE(wpc->iomap.type == IOMAP_INLINE)) {
- error = -EIO;
- break;
- }
- if (wpc->iomap.type == IOMAP_HOLE)
- continue;
- iomap_add_to_ioend(wpc, wbc, folio, inode, pos, &submit_list);
- count++;
}
if (count)
wpc->nr_folios++;
@@ -1854,21 +1885,6 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
WARN_ON_ONCE(folio_test_writeback(folio));
WARN_ON_ONCE(folio_test_dirty(folio));

- /*
- * We cannot cancel the ioend directly here on error. We may have
- * already set other pages under writeback and hence we have to run I/O
- * completion to mark the error state of the pages under writeback
- * appropriately.
- */
- if (unlikely(error)) {
- /*
- * Let the filesystem know what portion of the current page
- * failed to map.
- */
- if (wpc->ops->discard_folio)
- wpc->ops->discard_folio(folio, pos);
- }
-
/*
* We can have dirty bits set past end of file in page_mkwrite path
* while mapping the last partial folio. Hence it's better to clear
--
2.39.2