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linux/block/blk-sysfs.c
John Garry 9da3d1e912 block: Add core atomic write support 
Add atomic write support, as follows:
- add helper functions to get request_queue atomic write limits
- report request_queue atomic write support limits to sysfs and update Doc
- support to safely merge atomic writes
- deal with splitting atomic writes
- misc helper functions
- add a per-request atomic write flag

New request_queue limits are added, as follows:
- atomic_write_hw_max is set by the block driver and is the maximum length
  of an atomic write which the device may support. It is not
  necessarily a power-of-2.
- atomic_write_max_sectors is derived from atomic_write_hw_max_sectors and
  max_hw_sectors. It is always a power-of-2. Atomic writes may be merged,
  and atomic_write_max_sectors would be the limit on a merged atomic write
  request size. This value is not capped at max_sectors, as the value in
  max_sectors can be controlled from userspace, and it would only cause
  trouble if userspace could limit atomic_write_unit_max_bytes and the
  other atomic write limits.
- atomic_write_hw_unit_{min,max} are set by the block driver and are the
  min/max length of an atomic write unit which the device may support. They
  both must be a power-of-2. Typically atomic_write_hw_unit_max will hold
  the same value as atomic_write_hw_max.
- atomic_write_unit_{min,max} are derived from
  atomic_write_hw_unit_{min,max}, max_hw_sectors, and block core limits.
  Both min and max values must be a power-of-2.
- atomic_write_hw_boundary is set by the block driver. If non-zero, it
  indicates an LBA space boundary at which an atomic write straddles no
  longer is atomically executed by the disk. The value must be a
  power-of-2. Note that it would be acceptable to enforce a rule that
  atomic_write_hw_boundary_sectors is a multiple of
  atomic_write_hw_unit_max, but the resultant code would be more
  complicated.

All atomic writes limits are by default set 0 to indicate no atomic write
support. Even though it is assumed by Linux that a logical block can always
be atomically written, we ignore this as it is not of particular interest.
Stacked devices are just not supported either for now.

An atomic write must always be submitted to the block driver as part of a
single request. As such, only a single BIO must be submitted to the block
layer for an atomic write. When a single atomic write BIO is submitted, it
cannot be split. As such, atomic_write_unit_{max, min}_bytes are limited
by the maximum guaranteed BIO size which will not be required to be split.
This max size is calculated by request_queue max segments and the number
of bvecs a BIO can fit, BIO_MAX_VECS. Currently we rely on userspace
issuing a write with iovcnt=1 for pwritev2() - as such, we can rely on each
segment containing PAGE_SIZE of data, apart from the first+last, which each
can fit logical block size of data. The first+last will be LBS
length/aligned as we rely on direct IO alignment rules also.

New sysfs files are added to report the following atomic write limits:
- atomic_write_unit_max_bytes - same as atomic_write_unit_max_sectors in
				bytes
- atomic_write_unit_min_bytes - same as atomic_write_unit_min_sectors in
				bytes
- atomic_write_boundary_bytes - same as atomic_write_hw_boundary_sectors in
				bytes
- atomic_write_max_bytes      - same as atomic_write_max_sectors in bytes

Atomic writes may only be merged with other atomic writes and only under
the following conditions:
- total resultant request length <= atomic_write_max_bytes
- the merged write does not straddle a boundary

Helper function bdev_can_atomic_write() is added to indicate whether
atomic writes may be issued to a bdev. If a bdev is a partition, the
partition start must be aligned with both atomic_write_unit_min_sectors
and atomic_write_hw_boundary_sectors.

FSes will rely on the block layer to validate that an atomic write BIO
submitted will be of valid size, so add blk_validate_atomic_write_op_size()
for this purpose. Userspace expects an atomic write which is of invalid
size to be rejected with -EINVAL, so add BLK_STS_INVAL for this. Also use
BLK_STS_INVAL for when a BIO needs to be split, as this should mean an
invalid size BIO.

Flag REQ_ATOMIC is used for indicating an atomic write.

Co-developed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-6-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-06-20 15:19:17 -06:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Functions related to sysfs handling
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/blktrace_api.h>
#include <linux/debugfs.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-debugfs.h"
#include "blk-mq-sched.h"
#include "blk-rq-qos.h"
#include "blk-wbt.h"
#include "blk-cgroup.h"
#include "blk-throttle.h"
struct queue_sysfs_entry {
struct attribute attr;
ssize_t (*show)(struct request_queue *, char *);
ssize_t (*store)(struct request_queue *, const char *, size_t);
};
static ssize_t
queue_var_show(unsigned long var, char *page)
{
return sprintf(page, "%lu\n", var);
}
static ssize_t
queue_var_store(unsigned long *var, const char *page, size_t count)
{
int err;
unsigned long v;
err = kstrtoul(page, 10, &v);
if (err || v > UINT_MAX)
return -EINVAL;
*var = v;
return count;
}
static ssize_t queue_requests_show(struct request_queue *q, char *page)
{
return queue_var_show(q->nr_requests, page);
}
static ssize_t
queue_requests_store(struct request_queue *q, const char *page, size_t count)
{
unsigned long nr;
int ret, err;
if (!queue_is_mq(q))
return -EINVAL;
ret = queue_var_store(&nr, page, count);
if (ret < 0)
return ret;
if (nr < BLKDEV_MIN_RQ)
nr = BLKDEV_MIN_RQ;
err = blk_mq_update_nr_requests(q, nr);
if (err)
return err;
return ret;
}
static ssize_t queue_ra_show(struct request_queue *q, char *page)
{
unsigned long ra_kb;
if (!q->disk)
return -EINVAL;
ra_kb = q->disk->bdi->ra_pages << (PAGE_SHIFT - 10);
return queue_var_show(ra_kb, page);
}
static ssize_t
queue_ra_store(struct request_queue *q, const char *page, size_t count)
{
unsigned long ra_kb;
ssize_t ret;
if (!q->disk)
return -EINVAL;
ret = queue_var_store(&ra_kb, page, count);
if (ret < 0)
return ret;
q->disk->bdi->ra_pages = ra_kb >> (PAGE_SHIFT - 10);
return ret;
}
static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
{
int max_sectors_kb = queue_max_sectors(q) >> 1;
return queue_var_show(max_sectors_kb, page);
}
static ssize_t queue_max_segments_show(struct request_queue *q, char *page)
{
return queue_var_show(queue_max_segments(q), page);
}
static ssize_t queue_max_discard_segments_show(struct request_queue *q,
char *page)
{
return queue_var_show(queue_max_discard_segments(q), page);
}
static ssize_t queue_atomic_write_max_bytes_show(struct request_queue *q,
char *page)
{
return queue_var_show(queue_atomic_write_max_bytes(q), page);
}
static ssize_t queue_atomic_write_boundary_show(struct request_queue *q,
char *page)
{
return queue_var_show(queue_atomic_write_boundary_bytes(q), page);
}
static ssize_t queue_atomic_write_unit_min_show(struct request_queue *q,
char *page)
{
return queue_var_show(queue_atomic_write_unit_min_bytes(q), page);
}
static ssize_t queue_atomic_write_unit_max_show(struct request_queue *q,
char *page)
{
return queue_var_show(queue_atomic_write_unit_max_bytes(q), page);
}
static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *page)
{
return queue_var_show(q->limits.max_integrity_segments, page);
}
static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
{
return queue_var_show(queue_max_segment_size(q), page);
}
static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)
{
return queue_var_show(queue_logical_block_size(q), page);
}
static ssize_t queue_physical_block_size_show(struct request_queue *q, char *page)
{
return queue_var_show(queue_physical_block_size(q), page);
}
static ssize_t queue_chunk_sectors_show(struct request_queue *q, char *page)
{
return queue_var_show(q->limits.chunk_sectors, page);
}
static ssize_t queue_io_min_show(struct request_queue *q, char *page)
{
return queue_var_show(queue_io_min(q), page);
}
static ssize_t queue_io_opt_show(struct request_queue *q, char *page)
{
return queue_var_show(queue_io_opt(q), page);
}
static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
{
return queue_var_show(q->limits.discard_granularity, page);
}
static ssize_t queue_discard_max_hw_show(struct request_queue *q, char *page)
{
return sprintf(page, "%llu\n",
(unsigned long long)q->limits.max_hw_discard_sectors << 9);
}
static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
{
return sprintf(page, "%llu\n",
(unsigned long long)q->limits.max_discard_sectors << 9);
}
static ssize_t queue_discard_max_store(struct request_queue *q,
const char *page, size_t count)
{
unsigned long max_discard_bytes;
struct queue_limits lim;
ssize_t ret;
int err;
ret = queue_var_store(&max_discard_bytes, page, count);
if (ret < 0)
return ret;
if (max_discard_bytes & (q->limits.discard_granularity - 1))
return -EINVAL;
if ((max_discard_bytes >> SECTOR_SHIFT) > UINT_MAX)
return -EINVAL;
lim = queue_limits_start_update(q);
lim.max_user_discard_sectors = max_discard_bytes >> SECTOR_SHIFT;
err = queue_limits_commit_update(q, &lim);
if (err)
return err;
return ret;
}
static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
{
return queue_var_show(0, page);
}
static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
{
return queue_var_show(0, page);
}
static ssize_t queue_write_zeroes_max_show(struct request_queue *q, char *page)
{
return sprintf(page, "%llu\n",
(unsigned long long)q->limits.max_write_zeroes_sectors << 9);
}
static ssize_t queue_zone_write_granularity_show(struct request_queue *q,
char *page)
{
return queue_var_show(queue_zone_write_granularity(q), page);
}
static ssize_t queue_zone_append_max_show(struct request_queue *q, char *page)
{
unsigned long long max_sectors = queue_max_zone_append_sectors(q);
return sprintf(page, "%llu\n", max_sectors << SECTOR_SHIFT);
}
static ssize_t
queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
{
unsigned long max_sectors_kb;
struct queue_limits lim;
ssize_t ret;
int err;
ret = queue_var_store(&max_sectors_kb, page, count);
if (ret < 0)
return ret;
lim = queue_limits_start_update(q);
lim.max_user_sectors = max_sectors_kb << 1;
err = queue_limits_commit_update(q, &lim);
if (err)
return err;
return ret;
}
static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
{
int max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1;
return queue_var_show(max_hw_sectors_kb, page);
}
static ssize_t queue_virt_boundary_mask_show(struct request_queue *q, char *page)
{
return queue_var_show(q->limits.virt_boundary_mask, page);
}
static ssize_t queue_dma_alignment_show(struct request_queue *q, char *page)
{
return queue_var_show(queue_dma_alignment(q), page);
}
static ssize_t queue_feature_store(struct request_queue *q, const char *page,
size_t count, unsigned int feature)
{
struct queue_limits lim;
unsigned long val;
ssize_t ret;
ret = queue_var_store(&val, page, count);
if (ret < 0)
return ret;
lim = queue_limits_start_update(q);
if (val)
lim.features |= feature;
else
lim.features &= ~feature;
ret = queue_limits_commit_update(q, &lim);
if (ret)
return ret;
return count;
}
#define QUEUE_SYSFS_FEATURE(_name, _feature) \
static ssize_t queue_##_name##_show(struct request_queue *q, char *page) \
{ \
return sprintf(page, "%u\n", !!(q->limits.features & _feature)); \
} \
static ssize_t queue_##_name##_store(struct request_queue *q, \
const char *page, size_t count) \
{ \
return queue_feature_store(q, page, count, _feature); \
}
QUEUE_SYSFS_FEATURE(rotational, BLK_FEAT_ROTATIONAL)
QUEUE_SYSFS_FEATURE(add_random, BLK_FEAT_ADD_RANDOM)
QUEUE_SYSFS_FEATURE(iostats, BLK_FEAT_IO_STAT)
QUEUE_SYSFS_FEATURE(stable_writes, BLK_FEAT_STABLE_WRITES);
static ssize_t queue_zoned_show(struct request_queue *q, char *page)
{
if (blk_queue_is_zoned(q))
return sprintf(page, "host-managed\n");
return sprintf(page, "none\n");
}
static ssize_t queue_nr_zones_show(struct request_queue *q, char *page)
{
return queue_var_show(disk_nr_zones(q->disk), page);
}
static ssize_t queue_max_open_zones_show(struct request_queue *q, char *page)
{
return queue_var_show(bdev_max_open_zones(q->disk->part0), page);
}
static ssize_t queue_max_active_zones_show(struct request_queue *q, char *page)
{
return queue_var_show(bdev_max_active_zones(q->disk->part0), page);
}
static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
{
return queue_var_show((blk_queue_nomerges(q) << 1) |
blk_queue_noxmerges(q), page);
}
static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
size_t count)
{
unsigned long nm;
ssize_t ret = queue_var_store(&nm, page, count);
if (ret < 0)
return ret;
blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
blk_queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
if (nm == 2)
blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q);
else if (nm)
blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
return ret;
}
static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
{
bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
bool force = test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags);
return queue_var_show(set << force, page);
}
static ssize_t
queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
{
ssize_t ret = -EINVAL;
#ifdef CONFIG_SMP
unsigned long val;
ret = queue_var_store(&val, page, count);
if (ret < 0)
return ret;
if (val == 2) {
blk_queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
blk_queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
} else if (val == 1) {
blk_queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
blk_queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
} else if (val == 0) {
blk_queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
blk_queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
}
#endif
return ret;
}
static ssize_t queue_poll_delay_show(struct request_queue *q, char *page)
{
return sprintf(page, "%d\n", -1);
}
static ssize_t queue_poll_delay_store(struct request_queue *q, const char *page,
size_t count)
{
return count;
}
static ssize_t queue_poll_show(struct request_queue *q, char *page)
{
return queue_var_show(q->limits.features & BLK_FEAT_POLL, page);
}
static ssize_t queue_poll_store(struct request_queue *q, const char *page,
size_t count)
{
if (!(q->limits.features & BLK_FEAT_POLL))
return -EINVAL;
pr_info_ratelimited("writes to the poll attribute are ignored.\n");
pr_info_ratelimited("please use driver specific parameters instead.\n");
return count;
}
static ssize_t queue_io_timeout_show(struct request_queue *q, char *page)
{
return sprintf(page, "%u\n", jiffies_to_msecs(q->rq_timeout));
}
static ssize_t queue_io_timeout_store(struct request_queue *q, const char *page,
size_t count)
{
unsigned int val;
int err;
err = kstrtou32(page, 10, &val);
if (err || val == 0)
return -EINVAL;
blk_queue_rq_timeout(q, msecs_to_jiffies(val));
return count;
}
static ssize_t queue_wc_show(struct request_queue *q, char *page)
{
if (q->limits.features & BLK_FLAG_WRITE_CACHE_DISABLED)
return sprintf(page, "write through\n");
return sprintf(page, "write back\n");
}
static ssize_t queue_wc_store(struct request_queue *q, const char *page,
size_t count)
{
struct queue_limits lim;
bool disable;
int err;
if (!strncmp(page, "write back", 10)) {
disable = false;
} else if (!strncmp(page, "write through", 13) ||
!strncmp(page, "none", 4)) {
disable = true;
} else {
return -EINVAL;
}
lim = queue_limits_start_update(q);
if (disable)
lim.flags |= BLK_FLAG_WRITE_CACHE_DISABLED;
else
lim.flags &= ~BLK_FLAG_WRITE_CACHE_DISABLED;
err = queue_limits_commit_update(q, &lim);
if (err)
return err;
return count;
}
static ssize_t queue_fua_show(struct request_queue *q, char *page)
{
return sprintf(page, "%u\n", !!(q->limits.features & BLK_FEAT_FUA));
}
static ssize_t queue_dax_show(struct request_queue *q, char *page)
{
return queue_var_show(blk_queue_dax(q), page);
}
#define QUEUE_RO_ENTRY(_prefix, _name) \
static struct queue_sysfs_entry _prefix##_entry = { \
.attr = { .name = _name, .mode = 0444 }, \
.show = _prefix##_show, \
};
#define QUEUE_RW_ENTRY(_prefix, _name) \
static struct queue_sysfs_entry _prefix##_entry = { \
.attr = { .name = _name, .mode = 0644 }, \
.show = _prefix##_show, \
.store = _prefix##_store, \
};
QUEUE_RW_ENTRY(queue_requests, "nr_requests");
QUEUE_RW_ENTRY(queue_ra, "read_ahead_kb");
QUEUE_RW_ENTRY(queue_max_sectors, "max_sectors_kb");
QUEUE_RO_ENTRY(queue_max_hw_sectors, "max_hw_sectors_kb");
QUEUE_RO_ENTRY(queue_max_segments, "max_segments");
QUEUE_RO_ENTRY(queue_max_integrity_segments, "max_integrity_segments");
QUEUE_RO_ENTRY(queue_max_segment_size, "max_segment_size");
QUEUE_RW_ENTRY(elv_iosched, "scheduler");
QUEUE_RO_ENTRY(queue_logical_block_size, "logical_block_size");
QUEUE_RO_ENTRY(queue_physical_block_size, "physical_block_size");
QUEUE_RO_ENTRY(queue_chunk_sectors, "chunk_sectors");
QUEUE_RO_ENTRY(queue_io_min, "minimum_io_size");
QUEUE_RO_ENTRY(queue_io_opt, "optimal_io_size");
QUEUE_RO_ENTRY(queue_max_discard_segments, "max_discard_segments");
QUEUE_RO_ENTRY(queue_discard_granularity, "discard_granularity");
QUEUE_RO_ENTRY(queue_discard_max_hw, "discard_max_hw_bytes");
QUEUE_RW_ENTRY(queue_discard_max, "discard_max_bytes");
QUEUE_RO_ENTRY(queue_discard_zeroes_data, "discard_zeroes_data");
QUEUE_RO_ENTRY(queue_atomic_write_max_bytes, "atomic_write_max_bytes");
QUEUE_RO_ENTRY(queue_atomic_write_boundary, "atomic_write_boundary_bytes");
QUEUE_RO_ENTRY(queue_atomic_write_unit_max, "atomic_write_unit_max_bytes");
QUEUE_RO_ENTRY(queue_atomic_write_unit_min, "atomic_write_unit_min_bytes");
QUEUE_RO_ENTRY(queue_write_same_max, "write_same_max_bytes");
QUEUE_RO_ENTRY(queue_write_zeroes_max, "write_zeroes_max_bytes");
QUEUE_RO_ENTRY(queue_zone_append_max, "zone_append_max_bytes");
QUEUE_RO_ENTRY(queue_zone_write_granularity, "zone_write_granularity");
QUEUE_RO_ENTRY(queue_zoned, "zoned");
QUEUE_RO_ENTRY(queue_nr_zones, "nr_zones");
QUEUE_RO_ENTRY(queue_max_open_zones, "max_open_zones");
QUEUE_RO_ENTRY(queue_max_active_zones, "max_active_zones");
QUEUE_RW_ENTRY(queue_nomerges, "nomerges");
QUEUE_RW_ENTRY(queue_rq_affinity, "rq_affinity");
QUEUE_RW_ENTRY(queue_poll, "io_poll");
QUEUE_RW_ENTRY(queue_poll_delay, "io_poll_delay");
QUEUE_RW_ENTRY(queue_wc, "write_cache");
QUEUE_RO_ENTRY(queue_fua, "fua");
QUEUE_RO_ENTRY(queue_dax, "dax");
QUEUE_RW_ENTRY(queue_io_timeout, "io_timeout");
QUEUE_RO_ENTRY(queue_virt_boundary_mask, "virt_boundary_mask");
QUEUE_RO_ENTRY(queue_dma_alignment, "dma_alignment");
/* legacy alias for logical_block_size: */
static struct queue_sysfs_entry queue_hw_sector_size_entry = {
.attr = {.name = "hw_sector_size", .mode = 0444 },
.show = queue_logical_block_size_show,
};
QUEUE_RW_ENTRY(queue_rotational, "rotational");
QUEUE_RW_ENTRY(queue_iostats, "iostats");
QUEUE_RW_ENTRY(queue_add_random, "add_random");
QUEUE_RW_ENTRY(queue_stable_writes, "stable_writes");
#ifdef CONFIG_BLK_WBT
static ssize_t queue_var_store64(s64 *var, const char *page)
{
int err;
s64 v;
err = kstrtos64(page, 10, &v);
if (err < 0)
return err;
*var = v;
return 0;
}
static ssize_t queue_wb_lat_show(struct request_queue *q, char *page)
{
if (!wbt_rq_qos(q))
return -EINVAL;
if (wbt_disabled(q))
return sprintf(page, "0\n");
return sprintf(page, "%llu\n", div_u64(wbt_get_min_lat(q), 1000));
}
static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
size_t count)
{
struct rq_qos *rqos;
ssize_t ret;
s64 val;
ret = queue_var_store64(&val, page);
if (ret < 0)
return ret;
if (val < -1)
return -EINVAL;
rqos = wbt_rq_qos(q);
if (!rqos) {
ret = wbt_init(q->disk);
if (ret)
return ret;
}
if (val == -1)
val = wbt_default_latency_nsec(q);
else if (val >= 0)
val *= 1000ULL;
if (wbt_get_min_lat(q) == val)
return count;
/*
* Ensure that the queue is idled, in case the latency update
* ends up either enabling or disabling wbt completely. We can't
* have IO inflight if that happens.
*/
blk_mq_quiesce_queue(q);
wbt_set_min_lat(q, val);
blk_mq_unquiesce_queue(q);
return count;
}
QUEUE_RW_ENTRY(queue_wb_lat, "wbt_lat_usec");
#endif
/* Common attributes for bio-based and request-based queues. */
static struct attribute *queue_attrs[] = {
&queue_ra_entry.attr,
&queue_max_hw_sectors_entry.attr,
&queue_max_sectors_entry.attr,
&queue_max_segments_entry.attr,
&queue_max_discard_segments_entry.attr,
&queue_max_integrity_segments_entry.attr,
&queue_max_segment_size_entry.attr,
&queue_hw_sector_size_entry.attr,
&queue_logical_block_size_entry.attr,
&queue_physical_block_size_entry.attr,
&queue_chunk_sectors_entry.attr,
&queue_io_min_entry.attr,
&queue_io_opt_entry.attr,
&queue_discard_granularity_entry.attr,
&queue_discard_max_entry.attr,
&queue_discard_max_hw_entry.attr,
&queue_discard_zeroes_data_entry.attr,
&queue_atomic_write_max_bytes_entry.attr,
&queue_atomic_write_boundary_entry.attr,
&queue_atomic_write_unit_min_entry.attr,
&queue_atomic_write_unit_max_entry.attr,
&queue_write_same_max_entry.attr,
&queue_write_zeroes_max_entry.attr,
&queue_zone_append_max_entry.attr,
&queue_zone_write_granularity_entry.attr,
&queue_rotational_entry.attr,
&queue_zoned_entry.attr,
&queue_nr_zones_entry.attr,
&queue_max_open_zones_entry.attr,
&queue_max_active_zones_entry.attr,
&queue_nomerges_entry.attr,
&queue_iostats_entry.attr,
&queue_stable_writes_entry.attr,
&queue_add_random_entry.attr,
&queue_poll_entry.attr,
&queue_wc_entry.attr,
&queue_fua_entry.attr,
&queue_dax_entry.attr,
&queue_poll_delay_entry.attr,
&queue_virt_boundary_mask_entry.attr,
&queue_dma_alignment_entry.attr,
NULL,
};
/* Request-based queue attributes that are not relevant for bio-based queues. */
static struct attribute *blk_mq_queue_attrs[] = {
&queue_requests_entry.attr,
&elv_iosched_entry.attr,
&queue_rq_affinity_entry.attr,
&queue_io_timeout_entry.attr,
#ifdef CONFIG_BLK_WBT
&queue_wb_lat_entry.attr,
#endif
NULL,
};
static umode_t queue_attr_visible(struct kobject *kobj, struct attribute *attr,
int n)
{
struct gendisk *disk = container_of(kobj, struct gendisk, queue_kobj);
struct request_queue *q = disk->queue;
if ((attr == &queue_max_open_zones_entry.attr ||
attr == &queue_max_active_zones_entry.attr) &&
!blk_queue_is_zoned(q))
return 0;
return attr->mode;
}
static umode_t blk_mq_queue_attr_visible(struct kobject *kobj,
struct attribute *attr, int n)
{
struct gendisk *disk = container_of(kobj, struct gendisk, queue_kobj);
struct request_queue *q = disk->queue;
if (!queue_is_mq(q))
return 0;
if (attr == &queue_io_timeout_entry.attr && !q->mq_ops->timeout)
return 0;
return attr->mode;
}
static struct attribute_group queue_attr_group = {
.attrs = queue_attrs,
.is_visible = queue_attr_visible,
};
static struct attribute_group blk_mq_queue_attr_group = {
.attrs = blk_mq_queue_attrs,
.is_visible = blk_mq_queue_attr_visible,
};
#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
static ssize_t
queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
struct queue_sysfs_entry *entry = to_queue(attr);
struct gendisk *disk = container_of(kobj, struct gendisk, queue_kobj);
struct request_queue *q = disk->queue;
ssize_t res;
if (!entry->show)
return -EIO;
mutex_lock(&q->sysfs_lock);
res = entry->show(q, page);
mutex_unlock(&q->sysfs_lock);
return res;
}
static ssize_t
queue_attr_store(struct kobject *kobj, struct attribute *attr,
const char *page, size_t length)
{
struct queue_sysfs_entry *entry = to_queue(attr);
struct gendisk *disk = container_of(kobj, struct gendisk, queue_kobj);
struct request_queue *q = disk->queue;
ssize_t res;
if (!entry->store)
return -EIO;
blk_mq_freeze_queue(q);
mutex_lock(&q->sysfs_lock);
res = entry->store(q, page, length);
mutex_unlock(&q->sysfs_lock);
blk_mq_unfreeze_queue(q);
return res;
}
static const struct sysfs_ops queue_sysfs_ops = {
.show = queue_attr_show,
.store = queue_attr_store,
};
static const struct attribute_group *blk_queue_attr_groups[] = {
&queue_attr_group,
&blk_mq_queue_attr_group,
NULL
};
static void blk_queue_release(struct kobject *kobj)
{
/* nothing to do here, all data is associated with the parent gendisk */
}
static const struct kobj_type blk_queue_ktype = {
.default_groups = blk_queue_attr_groups,
.sysfs_ops = &queue_sysfs_ops,
.release = blk_queue_release,
};
static void blk_debugfs_remove(struct gendisk *disk)
{
struct request_queue *q = disk->queue;
mutex_lock(&q->debugfs_mutex);
blk_trace_shutdown(q);
debugfs_remove_recursive(q->debugfs_dir);
q->debugfs_dir = NULL;
q->sched_debugfs_dir = NULL;
q->rqos_debugfs_dir = NULL;
mutex_unlock(&q->debugfs_mutex);
}
/**
* blk_register_queue - register a block layer queue with sysfs
* @disk: Disk of which the request queue should be registered with sysfs.
*/
int blk_register_queue(struct gendisk *disk)
{
struct request_queue *q = disk->queue;
int ret;
mutex_lock(&q->sysfs_dir_lock);
kobject_init(&disk->queue_kobj, &blk_queue_ktype);
ret = kobject_add(&disk->queue_kobj, &disk_to_dev(disk)->kobj, "queue");
if (ret < 0)
goto out_put_queue_kobj;
if (queue_is_mq(q)) {
ret = blk_mq_sysfs_register(disk);
if (ret)
goto out_put_queue_kobj;
}
mutex_lock(&q->sysfs_lock);
mutex_lock(&q->debugfs_mutex);
q->debugfs_dir = debugfs_create_dir(disk->disk_name, blk_debugfs_root);
if (queue_is_mq(q))
blk_mq_debugfs_register(q);
mutex_unlock(&q->debugfs_mutex);
ret = disk_register_independent_access_ranges(disk);
if (ret)
goto out_debugfs_remove;
if (q->elevator) {
ret = elv_register_queue(q, false);
if (ret)
goto out_unregister_ia_ranges;
}
ret = blk_crypto_sysfs_register(disk);
if (ret)
goto out_elv_unregister;
blk_queue_flag_set(QUEUE_FLAG_REGISTERED, q);
wbt_enable_default(disk);
/* Now everything is ready and send out KOBJ_ADD uevent */
kobject_uevent(&disk->queue_kobj, KOBJ_ADD);
if (q->elevator)
kobject_uevent(&q->elevator->kobj, KOBJ_ADD);
mutex_unlock(&q->sysfs_lock);
mutex_unlock(&q->sysfs_dir_lock);
/*
* SCSI probing may synchronously create and destroy a lot of
* request_queues for non-existent devices. Shutting down a fully
* functional queue takes measureable wallclock time as RCU grace
* periods are involved. To avoid excessive latency in these
* cases, a request_queue starts out in a degraded mode which is
* faster to shut down and is made fully functional here as
* request_queues for non-existent devices never get registered.
*/
if (!blk_queue_init_done(q)) {
blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, q);
percpu_ref_switch_to_percpu(&q->q_usage_counter);
}
return ret;
out_elv_unregister:
elv_unregister_queue(q);
out_unregister_ia_ranges:
disk_unregister_independent_access_ranges(disk);
out_debugfs_remove:
blk_debugfs_remove(disk);
mutex_unlock(&q->sysfs_lock);
out_put_queue_kobj:
kobject_put(&disk->queue_kobj);
mutex_unlock(&q->sysfs_dir_lock);
return ret;
}
/**
* blk_unregister_queue - counterpart of blk_register_queue()
* @disk: Disk of which the request queue should be unregistered from sysfs.
*
* Note: the caller is responsible for guaranteeing that this function is called
* after blk_register_queue() has finished.
*/
void blk_unregister_queue(struct gendisk *disk)
{
struct request_queue *q = disk->queue;
if (WARN_ON(!q))
return;
/* Return early if disk->queue was never registered. */
if (!blk_queue_registered(q))
return;
/*
* Since sysfs_remove_dir() prevents adding new directory entries
* before removal of existing entries starts, protect against
* concurrent elv_iosched_store() calls.
*/
mutex_lock(&q->sysfs_lock);
blk_queue_flag_clear(QUEUE_FLAG_REGISTERED, q);
mutex_unlock(&q->sysfs_lock);
mutex_lock(&q->sysfs_dir_lock);
/*
* Remove the sysfs attributes before unregistering the queue data
* structures that can be modified through sysfs.
*/
if (queue_is_mq(q))
blk_mq_sysfs_unregister(disk);
blk_crypto_sysfs_unregister(disk);
mutex_lock(&q->sysfs_lock);
elv_unregister_queue(q);
disk_unregister_independent_access_ranges(disk);
mutex_unlock(&q->sysfs_lock);
/* Now that we've deleted all child objects, we can delete the queue. */
kobject_uevent(&disk->queue_kobj, KOBJ_REMOVE);
kobject_del(&disk->queue_kobj);
mutex_unlock(&q->sysfs_dir_lock);
blk_debugfs_remove(disk);
}
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