[PATCH v5 0/5] data placement hints and FDP

Kanchan Joshi
2024-09-10T15:11:10Z

Current write-hint infrastructure supports 6 temperature-based data
lifetime hints.
The series extends the infrastructure with a new temperature-agnostic
placement-type hint. New fcntl codes F_{SET/GET}_RW_HINT_EX allow to
send the hint type/value on file. See patch #3 commit description and
interface example below [*].

Overall this creates 127 placement hint values that users can pass.

Patch #5 adds the ability to map these new hint values to nvme-specific
placement-identifiers.
Patch #4 restricts SCSI to use only lifetime hint values.
Patch #1 and #2 are simple prep patches.

[*]
#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <inttypes.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <linux/fcntl.h>

int main(int argc, char *argv[])
{
struct rw_hint_ex set_hint_ex={}, get_hint_ex={};
int fd, ret;

if (argc < 4) {
fprintf(stderr, "Usage: %s file <hint type> <hint value>\n",
argv[0]);
return 1;
}

fd = open(argv[1], O_CREAT|O_RDWR|O_DIRECT, 0644);
if (fd < 0) {
perror("open");
return 1;
}

set_hint_ex.type = atoi(argv[2]);
set_hint_ex.val = atol(argv[3]);

ret = fcntl(fd, F_SET_RW_HINT_EX, &set_hint_ex);
if (ret < 0) {
perror("fcntl: Error, F_SET_RW_HINT_EX");
goto close_fd;
}
ret = fcntl(fd, F_GET_RW_HINT_EX, &get_hint_ex);
if (ret < 0) {
perror("fcntl: Error, F_GET_RW_HINT_EX");
goto close_fd;
}
printf("set_hint (%d,%llu)\nget_hint (%d,%llu)\n",
set_hint_ex.type, set_hint_ex.val,
get_hint_ex.type, get_hint_ex.val);

close_fd:
close(fd);
return 0;
}

/* set placement hint (type 2) with value 126 */
# ./a.out /dev/nvme0n1 2 126
set_hint (2,126)
get_hint (2,126)

/* invalid placement hint value */
# ./a.out /dev/nvme0n1 2 128
fcntl: Error, F_SET_RW_HINT_EX: Invalid argument

Changes since v4:
- Retain the size/type checking on the enum (Bart)
- Use the name "*_lifetime_hint" rather than "*_life_hint" (Bart)

Changes since v3:
- 4 new patches to introduce placement hints
- Make nvme patch use the placement hints rather than lifetime hints

Changes since v2:
- Base it on nvme-6.11 and resolve a merge conflict

Changes since v1:
- Reduce the fetched plids from 128 to 6 (Keith)
- Use struct_size for a calculation (Keith)
- Handle robot/sparse warning

Kanchan Joshi (4):
fs, block: refactor enum rw_hint
fcntl: rename rw_hint_* to rw_lifetime_hint_*
fcntl: add F_{SET/GET}_RW_HINT_EX
nvme: enable FDP support

Nitesh Shetty (1):
sd: limit to use write life hints

drivers/nvme/host/core.c | 81 ++++++++++++++++++++++++++++++++++++++
drivers/nvme/host/nvme.h | 4 ++
drivers/scsi/sd.c | 7 ++--
fs/buffer.c | 4 +-
fs/f2fs/f2fs.h | 5 ++-
fs/f2fs/segment.c | 5 ++-
fs/fcntl.c | 79 ++++++++++++++++++++++++++++++++++---
include/linux/blk-mq.h | 2 +-
include/linux/blk_types.h | 2 +-
include/linux/fs.h | 2 +-
include/linux/nvme.h | 19 +++++++++
include/linux/rw_hint.h | 17 +++++++-
include/uapi/linux/fcntl.h | 14 +++++++
13 files changed, 221 insertions(+), 20 deletions(-)

--
2.25.1