On Thu, May 05, 2022 at 03:11:10PM -0500, Christoph Hellwig wrote:
> Allow the file system to provide a specific bio_set for allocating
> direct I/O bios. This will allow file systems that use the
> ->submit_io hook to stash away additional information for file system
> use.
>
> To make use of this additional space for information in the completion
> path, the file system needs to override the ->bi_end_io callback and
> then call back into iomap, so export iomap_dio_bio_end_io for that.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
LGTM,
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> ---
> fs/iomap/direct-io.c | 18 ++++++++++++++----
> include/linux/iomap.h | 11 +++++++++++
> 2 files changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index b08f5dc31780d..15929690d89e3 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -51,6 +51,15 @@ struct iomap_dio {
> };
> };
>
> +static struct bio *iomap_dio_alloc_bio(const struct iomap_iter *iter,
> + struct iomap_dio *dio, unsigned short nr_vecs, unsigned int opf)
> +{
> + if (dio->dops && dio->dops->bio_set)
> + return bio_alloc_bioset(iter->iomap.bdev, nr_vecs, opf,
> + GFP_KERNEL, dio->dops->bio_set);
> + return bio_alloc(iter->iomap.bdev, nr_vecs, opf, GFP_KERNEL);
> +}
> +
> static void iomap_dio_submit_bio(const struct iomap_iter *iter,
> struct iomap_dio *dio, struct bio *bio, loff_t pos)
> {
> @@ -144,7 +153,7 @@ static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
> cmpxchg(&dio->error, 0, ret);
> }
>
> -static void iomap_dio_bio_end_io(struct bio *bio)
> +void iomap_dio_bio_end_io(struct bio *bio)
> {
> struct iomap_dio *dio = bio->bi_private;
> bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
> @@ -176,16 +185,17 @@ static void iomap_dio_bio_end_io(struct bio *bio)
> bio_put(bio);
> }
> }
> +EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io);
>
> static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
> loff_t pos, unsigned len)
> {
> struct inode *inode = file_inode(dio->iocb->ki_filp);
> struct page *page = ZERO_PAGE(0);
> - int flags = REQ_SYNC | REQ_IDLE;
> struct bio *bio;
>
> - bio = bio_alloc(iter->iomap.bdev, 1, REQ_OP_WRITE | flags, GFP_KERNEL);
> + bio = iomap_dio_alloc_bio(iter, dio, 1,
> + REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
> fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
> GFP_KERNEL);
> bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
> @@ -311,7 +321,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
> goto out;
> }
>
> - bio = bio_alloc(iomap->bdev, nr_pages, bio_opf, GFP_KERNEL);
> + bio = iomap_dio_alloc_bio(iter, dio, nr_pages, bio_opf);
> fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
> GFP_KERNEL);
> bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index b76f0dd149fb4..526c9e7f2eaf8 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -320,6 +320,16 @@ struct iomap_dio_ops {
> unsigned flags);
> void (*submit_io)(const struct iomap_iter *iter, struct bio *bio,
> loff_t file_offset);
> +
> + /*
> + * Filesystems wishing to attach private information to a directio bio
> + * must provide a ->submit_io method that attaches the additional
> + * information to the bio and changes the ->bi_end_io callback to a
> + * custom function. This function should, at a minimum, perform any
> + * relevant post-processing of the bio and end with a call to
> + * iomap_dio_bio_end_io.
> + */
> + struct bio_set *bio_set;
> };
>
> /*
> @@ -349,6 +359,7 @@ struct iomap_dio *__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
> unsigned int dio_flags, size_t done_before);
> ssize_t iomap_dio_complete(struct iomap_dio *dio);
> +void iomap_dio_bio_end_io(struct bio *bio);
>
> #ifdef CONFIG_SWAP
> struct file;
> --
> 2.30.2
>
