On 10/6/2023 1:10 AM, Bart Van Assche wrote:
> This patch reverts a small subset of commit c75e707fe1aa ("block: remove
> the per-bio/request write hint"). The following functionality has been
> restored:
> - In F2FS, store data lifetime information in struct bio.
> - In fs/iomap and fs/mpage.c, restore the code that sets the data
> lifetime.
>
> A new header file is introduced for the new bio_[sg]et_data_lifetime()
> functions because there is no other header file yet that includes both
> <linux/fs.h> and <linux/ioprio.h>.
>
> The value WRITE_LIFE_NONE is mapped onto the data lifetime 0. This is
> consistent with NVMe TPAR4093a. From that TPAR: "A value of 1h specifies
> the shortest Data Lifetime. A value of 3Fh specifies the longest Data
> Lifetime." This is also consistent with the SCSI specifications. From
> T10 document 23-024r3: "0h: no relative lifetime is applicable; 1h:
> shortest relative lifetime; ...; 3fh: longest relative lifetime".
>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> ---
> fs/f2fs/data.c | 3 +++
> fs/iomap/buffered-io.c | 3 +++
> fs/mpage.c | 2 ++
> include/linux/fs-lifetime.h | 20 ++++++++++++++++++++
> 4 files changed, 28 insertions(+)
> create mode 100644 include/linux/fs-lifetime.h
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 916e317ac925..2962cb335897 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -6,6 +6,7 @@
> * http://www.samsung.com/
> */
> #include <linux/fs.h>
> +#include <linux/fs-lifetime.h>
> #include <linux/f2fs_fs.h>
> #include <linux/buffer_head.h>
> #include <linux/sched/mm.h>
> @@ -478,6 +479,8 @@ static struct bio *__bio_alloc(struct f2fs_io_info *fio, int npages)
> } else {
> bio->bi_end_io = f2fs_write_end_io;
> bio->bi_private = sbi;
> + bio_set_data_lifetime(bio,
> + f2fs_io_type_to_rw_hint(sbi, fio->type, fio->temp));
> }
> iostat_alloc_and_bind_ctx(sbi, bio, NULL);
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 644479ccefbd..9bf05342ca65 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -6,6 +6,7 @@
> #include <linux/module.h>
> #include <linux/compiler.h>
> #include <linux/fs.h>
> +#include <linux/fs-lifetime.h>
> #include <linux/iomap.h>
> #include <linux/pagemap.h>
> #include <linux/uio.h>
> @@ -1660,6 +1661,7 @@ iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc,
> REQ_OP_WRITE | wbc_to_write_flags(wbc),
> GFP_NOFS, &iomap_ioend_bioset);
> bio->bi_iter.bi_sector = sector;
> + bio_set_data_lifetime(bio, inode->i_write_hint);
> wbc_init_bio(wbc, bio);
>
> ioend = container_of(bio, struct iomap_ioend, io_inline_bio);
> @@ -1690,6 +1692,7 @@ iomap_chain_bio(struct bio *prev)
> new = bio_alloc(prev->bi_bdev, BIO_MAX_VECS, prev->bi_opf, GFP_NOFS);
> bio_clone_blkg_association(new, prev);
> new->bi_iter.bi_sector = bio_end_sector(prev);
> + bio_set_data_lifetime(new, bio_get_data_lifetime(prev));
>
> bio_chain(prev, new);
> bio_get(prev); /* for iomap_finish_ioend */
> diff --git a/fs/mpage.c b/fs/mpage.c
> index 242e213ee064..888ca71c9ea7 100644
> --- a/fs/mpage.c
> +++ b/fs/mpage.c
> @@ -20,6 +20,7 @@
> #include <linux/gfp.h>
> #include <linux/bio.h>
> #include <linux/fs.h>
> +#include <linux/fs-lifetime.h>
> #include <linux/buffer_head.h>
> #include <linux/blkdev.h>
> #include <linux/highmem.h>
> @@ -612,6 +613,7 @@ static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc,
> GFP_NOFS);
> bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
> wbc_init_bio(wbc, bio);
> + bio_set_data_lifetime(bio, inode->i_write_hint);
> }
>
> /*
> diff --git a/include/linux/fs-lifetime.h b/include/linux/fs-lifetime.h
> new file mode 100644
> index 000000000000..0e652e00cfab
> --- /dev/null
> +++ b/include/linux/fs-lifetime.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <linux/bio.h>
> +#include <linux/fs.h>
> +#include <linux/ioprio.h>
> +
> +static inline enum rw_hint bio_get_data_lifetime(struct bio *bio)
> +{
> + /* +1 to map 0 onto WRITE_LIFE_NONE. */
> + return IOPRIO_PRIO_LIFETIME(bio->bi_ioprio) + 1;
> +}
> +
> +static inline void bio_set_data_lifetime(struct bio *bio, enum rw_hint lifetime)
> +{
> + /* -1 to map WRITE_LIFE_NONE onto 0. */
> + if (lifetime != 0)
> + lifetime--;
How the driver can figure when lifetime is not set, and when it is set
to WRITE_LIFE_NONE? If it uses IOPRIO_PRIO_LIFETIME (as patch 8 does),
it will see 0 in both cases.
F2FS fs-based whint_mode seems to expect distinct streams for
WRITE_LIFE_NOT_SET and WRITE_LIFE_NONE.
