Add a page_prepare calback that's called before a page is written to. This
will be used by gfs2 to start a transaction in page_prepare and end it in
page_done. Other filesystems that implement data journaling will require the
same kind of mechanism.
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
---
fs/iomap.c | 4 ++++
include/linux/iomap.h | 9 ++++++---
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/fs/iomap.c b/fs/iomap.c
index 97cb9d486a7d..abd9aa76dbd1 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -684,6 +684,10 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
status = __block_write_begin_int(page, pos, len, NULL, iomap);
else
status = __iomap_write_begin(inode, pos, len, page, iomap);
+
+ if (likely(!status) && iomap->page_prepare)
+ status = iomap->page_prepare(inode, pos, len, page, iomap);
+
if (unlikely(status)) {
unlock_page(page);
put_page(page);
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 0fefb5455bda..0982f3e13e56 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -65,10 +65,13 @@ struct iomap {
void *private; /* filesystem private */
/*
- * Called when finished processing a page in the mapping returned in
- * this iomap. At least for now this is only supported in the buffered
- * write path.
+ * Called before / after processing a page in the mapping returned in
+ * this iomap. At least for now, this is only supported in the
+ * buffered write path. When page_prepare returns 0 for a page,
+ * page_done is called for that page as well.
*/
+ int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len,
+ struct page *page, struct iomap *iomap);
void (*page_done)(struct inode *inode, loff_t pos, unsigned copied,
struct page *page, struct iomap *iomap);
};
--
2.20.1
