Add a IOMAP_F_ANON_WRITE flag that indicates that the write I/O does not
have a target block assigned to it yet at iomap time and the file system
will do that in the bio submission handler, splitting the I/O as needed.
This is used to implement Zone Append based I/O for zoned XFS, where
splitting writes to the hardware limits and assigning a zone to them
happens just before sending the I/O off to the block layer, but could
also be useful for other things like compressed I/O.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
Documentation/filesystems/iomap/design.rst | 4 ++++
fs/iomap/buffered-io.c | 13 +++++++++----
fs/iomap/direct-io.c | 6 ++++--
include/linux/iomap.h | 7 +++++++
4 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/Documentation/filesystems/iomap/design.rst b/Documentation/filesystems/iomap/design.rst
index b0d0188a095e..28ab3758c474 100644
--- a/Documentation/filesystems/iomap/design.rst
+++ b/Documentation/filesystems/iomap/design.rst
@@ -246,6 +246,10 @@ The fields are as follows:
* **IOMAP_F_PRIVATE**: Starting with this value, the upper bits can
be set by the filesystem for its own purposes.
+ * **IOMAP_F_ANON_WRITE**: Indicates that (write) I/O does not have a target
+ block assigned to it yet and the file system will do that in the bio
+ submission handler, splitting the I/O as needed.
+
These flags can be set by iomap itself during file operations.
The filesystem should supply an ``->iomap_end`` function if it needs
to observe these flags:
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 3176dc996fb7..8c18fb2a82e0 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1691,10 +1691,14 @@ static int iomap_submit_ioend(struct iomap_writepage_ctx *wpc, int error)
* failure happened so that the file system end I/O handler gets called
* to clean up.
*/
- if (wpc->ops->submit_ioend)
+ if (wpc->ops->submit_ioend) {
error = wpc->ops->submit_ioend(wpc, error);
- else if (!error)
- submit_bio(&wpc->ioend->io_bio);
+ } else {
+ if (WARN_ON_ONCE(wpc->iomap.flags & IOMAP_F_ANON_WRITE))
+ error = -EIO;
+ if (!error)
+ submit_bio(&wpc->ioend->io_bio);
+ }
if (error) {
wpc->ioend->io_bio.bi_status = errno_to_blk_status(error);
@@ -1744,7 +1748,8 @@ static bool iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t pos,
return false;
if (pos != wpc->ioend->io_offset + wpc->ioend->io_size)
return false;
- if (iomap_sector(&wpc->iomap, pos) !=
+ if (!(wpc->iomap.flags & IOMAP_F_ANON_WRITE) &&
+ iomap_sector(&wpc->iomap, pos) !=
bio_end_sector(&wpc->ioend->io_bio))
return false;
/*
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index b521eb15759e..641649a04614 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -81,10 +81,12 @@ static void iomap_dio_submit_bio(const struct iomap_iter *iter,
WRITE_ONCE(iocb->private, bio);
}
- if (dio->dops && dio->dops->submit_io)
+ if (dio->dops && dio->dops->submit_io) {
dio->dops->submit_io(iter, bio, pos);
- else
+ } else {
+ WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_ANON_WRITE);
submit_bio(bio);
+ }
}
ssize_t iomap_dio_complete(struct iomap_dio *dio)
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 31857d4750a9..36a7298b6cea 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -56,6 +56,10 @@ struct vm_fault;
*
* IOMAP_F_BOUNDARY indicates that I/O and I/O completions for this iomap must
* never be merged with the mapping before it.
+ *
+ * IOMAP_F_ANON_WRITE indicates that (write) I/O does not have a target block
+ * assigned to it yet and the file system will do that in the bio submission
+ * handler, splitting the I/O as needed.
*/
#define IOMAP_F_NEW (1U << 0)
#define IOMAP_F_DIRTY (1U << 1)
@@ -68,6 +72,7 @@ struct vm_fault;
#endif /* CONFIG_BUFFER_HEAD */
#define IOMAP_F_XATTR (1U << 5)
#define IOMAP_F_BOUNDARY (1U << 6)
+#define IOMAP_F_ANON_WRITE (1U << 7)
/*
* Flags set by the core iomap code during operations:
@@ -111,6 +116,8 @@ struct iomap {
static inline sector_t iomap_sector(const struct iomap *iomap, loff_t pos)
{
+ if (iomap->flags & IOMAP_F_ANON_WRITE)
+ return U64_MAX; /* invalid */
return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
}
--
2.45.2
