This allows IOMAP_IN_MEM iomaps to use iomap_writepages() for handling
writeback. This lets IOMAP_IN_MEM iomaps use some of the internal
features in iomaps such as granular dirty tracking for large folios.
This introduces a new iomap_writeback_ops callback, writeback_folio(),
callers may pass in which hands off folio writeback logic to the caller
for writing back dirty pages instead of relying on mapping blocks.
This exposes two apis, iomap_start_folio_write() and
iomap_finish_folio_write(), which callers may find useful in their
writeback_folio() callback implementation.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
fs/iomap/buffered-io-bio.c | 12 --------
fs/iomap/buffered-io.c | 60 ++++++++++++++++++++++++++++++++------
include/linux/iomap.h | 18 ++++++++++--
3 files changed, 67 insertions(+), 23 deletions(-)
diff --git a/fs/iomap/buffered-io-bio.c b/fs/iomap/buffered-io-bio.c
index 03841bed72e7..b7bc838cf477 100644
--- a/fs/iomap/buffered-io-bio.c
+++ b/fs/iomap/buffered-io-bio.c
@@ -96,18 +96,6 @@ int iomap_bio_read_folio_sync(loff_t block_start, struct folio *folio, size_t po
return submit_bio_wait(&bio);
}
-static void iomap_finish_folio_write(struct inode *inode, struct folio *folio,
- size_t len)
-{
- struct iomap_folio_state *ifs = folio->private;
-
- WARN_ON_ONCE(i_blocks_per_folio(inode, folio) > 1 && !ifs);
- WARN_ON_ONCE(ifs && atomic_read(&ifs->write_bytes_pending) <= 0);
-
- if (!ifs || atomic_sub_and_test(len, &ifs->write_bytes_pending))
- folio_end_writeback(folio);
-}
-
/*
* We're now finished for good with this ioend structure. Update the page
* state, release holds on bios, and finally free up memory. Do not use the
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index fd2ea1306d88..92f08b316d47 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1441,15 +1441,15 @@ EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
/*
* Submit an ioend.
- *
- * If @error is non-zero, it means that we have a situation where some part of
- * the submission process has failed after we've marked pages for writeback.
- * We cannot cancel ioend directly in that case, so call the bio end I/O handler
- * with the error status here to run the normal I/O completion handler to clear
- * the writeback bit and let the file system proess the errors.
*/
int iomap_submit_ioend(struct iomap_writepage_ctx *wpc, int error)
{
+ if (wpc->iomap.type == IOMAP_IN_MEM) {
+ if (wpc->ops->submit_ioend)
+ error = wpc->ops->submit_ioend(wpc, error);
+ return error;
+ }
+
if (!wpc->ioend)
return error;
@@ -1468,6 +1468,13 @@ int iomap_submit_ioend(struct iomap_writepage_ctx *wpc, int error)
iomap_submit_bio(&wpc->ioend->io_bio);
}
+ /*
+ * If error is non-zero, it means that we have a situation where some part of
+ * the submission process has failed after we've marked pages for writeback.
+ * We cannot cancel ioend directly in that case, so call the bio end I/O handler
+ * with the error status here to run the normal I/O completion handler to clear
+ * the writeback bit and let the file system process the errors.
+ */
if (error)
iomap_bio_ioend_error(wpc, error);
@@ -1635,8 +1642,17 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
*/
end_aligned = round_up(end_pos, i_blocksize(inode));
while ((rlen = iomap_find_dirty_range(folio, &pos, end_aligned))) {
- error = iomap_writepage_map_blocks(wpc, wbc, folio, inode,
- pos, end_pos, rlen, &count);
+ if (wpc->ops->writeback_folio) {
+ WARN_ON_ONCE(wpc->ops->map_blocks);
+ error = wpc->ops->writeback_folio(wpc, folio, inode,
+ offset_in_folio(folio, pos),
+ rlen);
+ } else {
+ WARN_ON_ONCE(wpc->iomap.type == IOMAP_IN_MEM);
+ error = iomap_writepage_map_blocks(wpc, wbc, folio,
+ inode, pos, end_pos,
+ rlen, &count);
+ }
if (error)
break;
pos += rlen;
@@ -1664,7 +1680,11 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
if (atomic_dec_and_test(&ifs->write_bytes_pending))
folio_end_writeback(folio);
} else {
- if (!count)
+ /*
+ * If wpc->ops->writeback_folio is set, then it is responsible
+ * for ending the writeback itself.
+ */
+ if (!count && !wpc->ops->writeback_folio)
folio_end_writeback(folio);
}
mapping_set_error(inode->i_mapping, error);
@@ -1693,3 +1713,25 @@ iomap_writepages(struct address_space *mapping, struct writeback_control *wbc,
return iomap_submit_ioend(wpc, error);
}
EXPORT_SYMBOL_GPL(iomap_writepages);
+
+void iomap_start_folio_write(struct inode *inode, struct folio *folio, size_t len)
+{
+ struct iomap_folio_state *ifs = folio->private;
+
+ WARN_ON_ONCE(i_blocks_per_folio(inode, folio) > 1 && !ifs);
+ if (ifs)
+ atomic_add(len, &ifs->write_bytes_pending);
+}
+EXPORT_SYMBOL_GPL(iomap_start_folio_write);
+
+void iomap_finish_folio_write(struct inode *inode, struct folio *folio, size_t len)
+{
+ struct iomap_folio_state *ifs = folio->private;
+
+ WARN_ON_ONCE(i_blocks_per_folio(inode, folio) > 1 && !ifs);
+ WARN_ON_ONCE(ifs && atomic_read(&ifs->write_bytes_pending) <= 0);
+
+ if (!ifs || atomic_sub_and_test(len, &ifs->write_bytes_pending))
+ folio_end_writeback(folio);
+}
+EXPORT_SYMBOL_GPL(iomap_finish_folio_write);
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index e748aeebe1a5..4b5e083fa802 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -424,8 +424,8 @@ static inline struct iomap_ioend *iomap_ioend_from_bio(struct bio *bio)
struct iomap_writeback_ops {
/*
- * Required, maps the blocks so that writeback can be performed on
- * the range starting at offset.
+ * Required if ->writeback_folio is not set. Maps the blocks so that
+ * writeback can be performed on the range starting at offset.
*
* Can return arbitrarily large regions, but we need to call into it at
* least once per folio to allow the file systems to synchronize with
@@ -436,6 +436,16 @@ struct iomap_writeback_ops {
*/
int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode,
loff_t offset, unsigned len);
+ /*
+ * Forwards the folio writeback logic to the caller.
+ *
+ * Required for IOMAP_IN_MEM iomaps or if ->map_blocks is not set.
+ *
+ * The caller is responsible for ending writeback on the folio after
+ * it's fully done processing it.
+ */
+ int (*writeback_folio)(struct iomap_writepage_ctx *wpc, struct folio *folio,
+ struct inode *inode, loff_t offset, unsigned len);
/*
* Optional, allows the file systems to hook into bio submission,
@@ -459,6 +469,7 @@ struct iomap_writepage_ctx {
struct iomap_ioend *ioend;
const struct iomap_writeback_ops *ops;
u32 nr_folios; /* folios added to the ioend */
+ void *private;
};
struct iomap_ioend *iomap_init_ioend(struct inode *inode, struct bio *bio,
@@ -538,4 +549,7 @@ int iomap_swapfile_activate(struct swap_info_struct *sis,
extern struct bio_set iomap_ioend_bioset;
+void iomap_start_folio_write(struct inode *inode, struct folio *folio, size_t len);
+void iomap_finish_folio_write(struct inode *inode, struct folio *folio, size_t len);
+
#endif /* LINUX_IOMAP_H */
--
2.47.1
