[PATCH RFC 01/29] iomap: add iomap_writepages_unbound() to write beyond EOF

Andrey Albershteyn
2025-07-28T20:31:26Z

From: Andrey Albershteyn <aalbersh@redhat.com>

Add iomap_writepages_unbound() without limit in form of EOF. XFS
will use this to write metadata (fs-verity Merkle tree) in range far
beyond EOF.

Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
---
fs/iomap/buffered-io.c | 51 +++++++++++++++++++++++++++++++++++++++-----------
include/linux/iomap.h | 3 +++
2 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 3729391a18f3..7bef232254a3 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1881,18 +1881,10 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
int error = 0;
u32 rlen;

- WARN_ON_ONCE(!folio_test_locked(folio));
- WARN_ON_ONCE(folio_test_dirty(folio));
- WARN_ON_ONCE(folio_test_writeback(folio));
-
- trace_iomap_writepage(inode, pos, folio_size(folio));
-
- if (!iomap_writepage_handle_eof(folio, inode, &end_pos)) {
- folio_unlock(folio);
- return 0;
- }
WARN_ON_ONCE(end_pos <= pos);

+ trace_iomap_writepage(inode, pos, folio_size(folio));
+
if (i_blocks_per_folio(inode, folio) > 1) {
if (!ifs) {
ifs = ifs_alloc(inode, folio, 0);
@@ -1956,6 +1948,23 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
return error;
}

+/* Map pages bound by EOF */
+static int iomap_writepage_map_eof(struct iomap_writepage_ctx *wpc,
+ struct writeback_control *wbc, struct folio *folio)
+{
+ int error;
+ struct inode *inode = folio->mapping->host;
+ u64 end_pos = folio_pos(folio) + folio_size(folio);
+
+ if (!iomap_writepage_handle_eof(folio, inode, &end_pos)) {
+ folio_unlock(folio);
+ return 0;
+ }
+
+ error = iomap_writepage_map(wpc, wbc, folio);
+ return error;
+}
+
int
iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
struct iomap_writepage_ctx *wpc,
@@ -1972,9 +1981,29 @@ iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
PF_MEMALLOC))
return -EIO;

+ wpc->ops = ops;
+ while ((folio = writeback_iter(mapping, wbc, folio, &error))) {
+ WARN_ON_ONCE(!folio_test_locked(folio));
+ WARN_ON_ONCE(folio_test_dirty(folio));
+ WARN_ON_ONCE(folio_test_writeback(folio));
+
+ error = iomap_writepage_map_eof(wpc, wbc, folio);
+ }
+ return iomap_submit_ioend(wpc, error);
+}
+EXPORT_SYMBOL_GPL(iomap_writepages);
+
+int
+iomap_writepages_unbound(struct address_space *mapping, struct writeback_control *wbc,
+ struct iomap_writepage_ctx *wpc,
+ const struct iomap_writeback_ops *ops)
+{
+ struct folio *folio = NULL;
+ int error;
+
wpc->ops = ops;
while ((folio = writeback_iter(mapping, wbc, folio, &error)))
error = iomap_writepage_map(wpc, wbc, folio);
return iomap_submit_ioend(wpc, error);
}
-EXPORT_SYMBOL_GPL(iomap_writepages);
+EXPORT_SYMBOL_GPL(iomap_writepages_unbound);
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 522644d62f30..4a0b5ebb79e9 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -464,6 +464,9 @@ void iomap_sort_ioends(struct list_head *ioend_list);
int iomap_writepages(struct address_space *mapping,
struct writeback_control *wbc, struct iomap_writepage_ctx *wpc,
const struct iomap_writeback_ops *ops);
+int iomap_writepages_unbound(struct address_space *mapping,
+ struct writeback_control *wbc, struct iomap_writepage_ctx *wpc,
+ const struct iomap_writeback_ops *ops);

/*
* Flags for direct I/O ->end_io:

--
2.50.0