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iomap: add read_folio_range() handler for buffered writes

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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@gmail.com>
[hch: renamed to read_folio_range, pass less arguments]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/20250710133343.399917-14-hch@lst.de
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christoph Hellwig
2025-07-10 15:33:37 +02:00
committed by Christian Brauner
parent e6caf01d3f
commit c5690dd019
3 changed files with 25 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
Documentation/filesystems/iomap/operations.rst
View File

@@ -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``.

13
fs/iomap/buffered-io.c
View File

@@ -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;

10
include/linux/iomap.h
View File

@@ -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);
};
/*