Add a read_folio_range() handler for buffered writes that filesystems
may pass in if they wish to provide a custom handler for synchronously
reading in the contents of a folio.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
[hch: renamed to read_folio_range, pass less arguments]
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
Documentation/filesystems/iomap/operations.rst | 6 ++++++
fs/iomap/buffered-io.c | 13 +++++++++----
include/linux/iomap.h | 10 ++++++++++
3 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/Documentation/filesystems/iomap/operations.rst b/Documentation/filesystems/iomap/operations.rst
index a9b48ce4af92..067ed8e14ef3 100644
--- a/Documentation/filesystems/iomap/operations.rst
+++ b/Documentation/filesystems/iomap/operations.rst
@@ -68,6 +68,8 @@ The following address space operations can be wrapped easily:
void (*put_folio)(struct inode *inode, loff_t pos, unsigned copied,
struct folio *folio);
bool (*iomap_valid)(struct inode *inode, const struct iomap *iomap);
+ int (*read_folio_range)(const struct iomap_iter *iter,
+ struct folio *folio, loff_t pos, size_t len);
};
iomap calls these functions:
@@ -123,6 +125,10 @@ iomap calls these functions:
``->iomap_valid``, then the iomap should considered stale and the
validation failed.
+ - ``read_folio_range``: Called to synchronously read in the range that will
+ be written to. If this function is not provided, iomap will default to
+ submitting a bio read request.
+
These ``struct kiocb`` flags are significant for buffered I/O with iomap:
* ``IOCB_NOWAIT``: Turns on ``IOMAP_NOWAIT``.
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 8a44f56a3a80..aed4fc30a849 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -671,7 +671,8 @@ static int iomap_read_folio_range(const struct iomap_iter *iter,
return submit_bio_wait(&bio);
}
-static int __iomap_write_begin(const struct iomap_iter *iter, size_t len,
+static int __iomap_write_begin(const struct iomap_iter *iter,
+ const struct iomap_write_ops *write_ops, size_t len,
struct folio *folio)
{
struct iomap_folio_state *ifs;
@@ -722,8 +723,12 @@ static int __iomap_write_begin(const struct iomap_iter *iter, size_t len,
if (iter->flags & IOMAP_NOWAIT)
return -EAGAIN;
- status = iomap_read_folio_range(iter, folio,
- block_start, plen);
+ if (write_ops && write_ops->read_folio_range)
+ status = write_ops->read_folio_range(iter,
+ folio, block_start, plen);
+ else
+ status = iomap_read_folio_range(iter,
+ folio, block_start, plen);
if (status)
return status;
}
@@ -839,7 +844,7 @@ static int iomap_write_begin(struct iomap_iter *iter,
else if (srcmap->flags & IOMAP_F_BUFFER_HEAD)
status = __block_write_begin_int(folio, pos, len, NULL, srcmap);
else
- status = __iomap_write_begin(iter, len, folio);
+ status = __iomap_write_begin(iter, write_ops, len, folio);
if (unlikely(status))
goto out_unlock;
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 80f543cc4fe8..73dceabc21c8 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -166,6 +166,16 @@ struct iomap_write_ops {
* locked by the iomap code.
*/
bool (*iomap_valid)(struct inode *inode, const struct iomap *iomap);
+
+ /*
+ * Optional if the filesystem wishes to provide a custom handler for
+ * reading in the contents of a folio, otherwise iomap will default to
+ * submitting a bio read request.
+ *
+ * The read must be done synchronously.
+ */
+ int (*read_folio_range)(const struct iomap_iter *iter,
+ struct folio *folio, loff_t pos, size_t len);
};
/*
--
2.47.2
