Move the page_done callback into a separate iomap_page_ops structure and
add a page_prepare calback to be called before the next page is written
to. In gfs2, we'll want 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/gfs2/bmap.c | 22 +++++++++++++++++-----
fs/iomap.c | 36 ++++++++++++++++++++++++++----------
include/linux/iomap.h | 22 +++++++++++++++++-----
3 files changed, 60 insertions(+), 20 deletions(-)
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 5da4ca9041c0..6b980703bae7 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -991,15 +991,27 @@ static void gfs2_write_unlock(struct inode *inode)
gfs2_glock_dq_uninit(&ip->i_gh);
}
-static void gfs2_iomap_journaled_page_done(struct inode *inode, loff_t pos,
- unsigned copied, struct page *page,
- struct iomap *iomap)
+static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos,
+ unsigned len, struct iomap *iomap)
+{
+ return 0;
+}
+
+static void gfs2_iomap_page_done(struct inode *inode, loff_t pos,
+ unsigned copied, struct page *page,
+ struct iomap *iomap)
{
struct gfs2_inode *ip = GFS2_I(inode);
- gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied);
+ if (page)
+ gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied);
}
+static const struct iomap_page_ops gfs2_iomap_page_ops = {
+ .page_prepare = gfs2_iomap_page_prepare,
+ .page_done = gfs2_iomap_page_done,
+};
+
static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
loff_t length, unsigned flags,
struct iomap *iomap,
@@ -1077,7 +1089,7 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos,
}
}
if (!gfs2_is_stuffed(ip) && gfs2_is_jdata(ip))
- iomap->page_done = gfs2_iomap_journaled_page_done;
+ iomap->page_ops = &gfs2_iomap_page_ops;
return 0;
out_trans_end:
diff --git a/fs/iomap.c b/fs/iomap.c
index b01ed5a28d2c..ee9ce7a06244 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -665,6 +665,7 @@ static int
iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
struct page **pagep, struct iomap *iomap)
{
+ const struct iomap_page_ops *page_ops = iomap->page_ops;
pgoff_t index = pos >> PAGE_SHIFT;
struct page *page;
int status = 0;
@@ -674,9 +675,17 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
if (fatal_signal_pending(current))
return -EINTR;
+ if (page_ops && page_ops->page_prepare) {
+ status = page_ops->page_prepare(inode, pos, len, iomap);
+ if (status)
+ return status;
+ }
+
page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
- if (!page)
- return -ENOMEM;
+ if (!page) {
+ status = -ENOMEM;
+ goto out_no_page;
+ }
if (iomap->type == IOMAP_INLINE)
iomap_read_inline_data(inode, page, iomap);
@@ -684,15 +693,21 @@ 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 (unlikely(status)) {
- unlock_page(page);
- put_page(page);
- page = NULL;
- iomap_write_failed(inode, pos, len);
- }
+ if (unlikely(status))
+ goto out_unlock;
*pagep = page;
+ return 0;
+
+out_unlock:
+ unlock_page(page);
+ put_page(page);
+ iomap_write_failed(inode, pos, len);
+
+out_no_page:
+ if (page_ops && page_ops->page_done)
+ page_ops->page_done(inode, pos, 0, NULL, iomap);
return status;
}
@@ -766,6 +781,7 @@ static int
iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
unsigned copied, struct page *page, struct iomap *iomap)
{
+ const struct iomap_page_ops *page_ops = iomap->page_ops;
int ret;
if (iomap->type == IOMAP_INLINE) {
@@ -778,8 +794,8 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
}
ret = __generic_write_end(inode, pos, ret, page);
- if (iomap->page_done)
- iomap->page_done(inode, pos, copied, page, iomap);
+ if (page_ops)
+ page_ops->page_done(inode, pos, copied, page, iomap);
put_page(page);
if (ret < len)
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 0fefb5455bda..2103b94cb1bf 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -53,6 +53,8 @@ struct vm_fault;
*/
#define IOMAP_NULL_ADDR -1ULL /* addr is not valid */
+struct iomap_page_ops;
+
struct iomap {
u64 addr; /* disk offset of mapping, bytes */
loff_t offset; /* file offset of mapping, bytes */
@@ -63,12 +65,22 @@ struct iomap {
struct dax_device *dax_dev; /* dax_dev for dax operations */
void *inline_data;
void *private; /* filesystem private */
+ const struct iomap_page_ops *page_ops;
+};
- /*
- * 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.
- */
+/*
+ * When a filesystem sets page_ops in an iomap mapping it returns, page_prepare
+ * and page_done will be called for each page written to. This only applies to
+ * buffered writes as unbuffered writes will not typically have pages
+ * associated with them.
+ *
+ * When page_prepare succeeds, page_done will always be called to do any
+ * cleanup work necessary. In that page_done call, @page will be NULL if the
+ * associated page could not be obtained.
+ */
+struct iomap_page_ops {
+ int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len,
+ struct iomap *iomap);
void (*page_done)(struct inode *inode, loff_t pos, unsigned copied,
struct page *page, struct iomap *iomap);
};
--
2.20.1
