[PATCH v3 1/8] iomap: export iomap_bio_read_folio_range_sync()

[Chi Zhiling <chizhiling@163.com>]

From: Chi Zhiling <chizhiling@kylinos.cn>

Filesystems that provide a buffered write ->read_folio_range handler
need to perform the same synchronous bio read as the default handler.
Move the declaration of iomap_bio_read_folio_range_sync() from the
internal header to <linux/iomap.h>, together with the !CONFIG_BLOCK
fallback, and export it so that modular filesystems can call it.

exfat will call it from its own ->read_folio_range handler to zero
the stale bytes between valid_size and the end of the block under
the folio lock during buffered writes.

Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
---
 fs/iomap/bio.c        |  1 +
 fs/iomap/internal.h   | 12 ------------
 include/linux/iomap.h |  9 +++++++++
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/fs/iomap/bio.c b/fs/iomap/bio.c
index 48100c614431..abb649f024a3 100644
--- a/fs/iomap/bio.c
+++ b/fs/iomap/bio.c
@@ -187,3 +187,4 @@ int iomap_bio_read_folio_range_sync(const struct iomap_iter *iter,
 	bio_uninit(&bio);
 	return error;
 }
+EXPORT_SYMBOL_GPL(iomap_bio_read_folio_range_sync);
diff --git a/fs/iomap/internal.h b/fs/iomap/internal.h
index 74e898b196dc..d13aff5e1e91 100644
--- a/fs/iomap/internal.h
+++ b/fs/iomap/internal.h
@@ -20,16 +20,4 @@ static inline size_t iomap_max_bio_size(const struct iomap *iomap)
 u32 iomap_finish_ioend_buffered_read(struct iomap_ioend *ioend);
 u32 iomap_finish_ioend_direct(struct iomap_ioend *ioend);
 
-#ifdef CONFIG_BLOCK
-int iomap_bio_read_folio_range_sync(const struct iomap_iter *iter,
-		struct folio *folio, loff_t pos, size_t len);
-#else
-static inline int iomap_bio_read_folio_range_sync(const struct iomap_iter *iter,
-		struct folio *folio, loff_t pos, size_t len)
-{
-	WARN_ON_ONCE(1);
-	return -EIO;
-}
-#endif /* CONFIG_BLOCK */
-
 #endif /* _IOMAP_INTERNAL_H */
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index bc7ae6327dbf..35b686cbb586 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -763,6 +763,8 @@ extern struct bio_set iomap_ioend_bioset;
 #ifdef CONFIG_BLOCK
 int iomap_bio_read_folio_range(const struct iomap_iter *iter,
 		struct iomap_read_folio_ctx *ctx, size_t plen);
+int iomap_bio_read_folio_range_sync(const struct iomap_iter *iter,
+		struct folio *folio, loff_t pos, size_t len);
 void iomap_bio_submit_read_endio(const struct iomap_iter *iter,
 		struct iomap_read_folio_ctx *ctx, bio_end_io_t end_io);
 
@@ -789,6 +791,13 @@ static inline void iomap_bio_readahead(struct readahead_control *rac,
 
 	iomap_readahead(ops, &ctx, NULL);
 }
+#else /* !CONFIG_BLOCK */
+static inline int iomap_bio_read_folio_range_sync(const struct iomap_iter *iter,
+		struct folio *folio, loff_t pos, size_t len)
+{
+	WARN_ON_ONCE(1);
+	return -EIO;
+}
 #endif /* CONFIG_BLOCK */
 
 #endif /* LINUX_IOMAP_H */
-- 
2.53.0