linux/block/blk-sysfs.c
Ming Lei cecf5d87ff block: split .sysfs_lock into two locks
The kernfs built-in lock of 'kn->count' is held in sysfs .show/.store
path. Meantime, inside block's .show/.store callback, q->sysfs_lock is
required.

However, when mq & iosched kobjects are removed via
blk_mq_unregister_dev() & elv_unregister_queue(), q->sysfs_lock is held
too. This way causes AB-BA lock because the kernfs built-in lock of
'kn-count' is required inside kobject_del() too, see the lockdep warning[1].

On the other hand, it isn't necessary to acquire q->sysfs_lock for
both blk_mq_unregister_dev() & elv_unregister_queue() because
clearing REGISTERED flag prevents storing to 'queue/scheduler'
from being happened. Also sysfs write(store) is exclusive, so no
necessary to hold the lock for elv_unregister_queue() when it is
called in switching elevator path.

So split .sysfs_lock into two: one is still named as .sysfs_lock for
covering sync .store, the other one is named as .sysfs_dir_lock
for covering kobjects and related status change.

sysfs itself can handle the race between add/remove kobjects and
showing/storing attributes under kobjects. For switching scheduler
via storing to 'queue/scheduler', we use the queue flag of
QUEUE_FLAG_REGISTERED with .sysfs_lock for avoiding the race, then
we can avoid to hold .sysfs_lock during removing/adding kobjects.

[1]  lockdep warning
    ======================================================
    WARNING: possible circular locking dependency detected
    5.3.0-rc3-00044-g73277fc75ea0 #1380 Not tainted
    ------------------------------------------------------
    rmmod/777 is trying to acquire lock:
    00000000ac50e981 (kn->count#202){++++}, at: kernfs_remove_by_name_ns+0x59/0x72

    but task is already holding lock:
    00000000fb16ae21 (&q->sysfs_lock){+.+.}, at: blk_unregister_queue+0x78/0x10b

    which lock already depends on the new lock.

    the existing dependency chain (in reverse order) is:

    -> #1 (&q->sysfs_lock){+.+.}:
           __lock_acquire+0x95f/0xa2f
           lock_acquire+0x1b4/0x1e8
           __mutex_lock+0x14a/0xa9b
           blk_mq_hw_sysfs_show+0x63/0xb6
           sysfs_kf_seq_show+0x11f/0x196
           seq_read+0x2cd/0x5f2
           vfs_read+0xc7/0x18c
           ksys_read+0xc4/0x13e
           do_syscall_64+0xa7/0x295
           entry_SYSCALL_64_after_hwframe+0x49/0xbe

    -> #0 (kn->count#202){++++}:
           check_prev_add+0x5d2/0xc45
           validate_chain+0xed3/0xf94
           __lock_acquire+0x95f/0xa2f
           lock_acquire+0x1b4/0x1e8
           __kernfs_remove+0x237/0x40b
           kernfs_remove_by_name_ns+0x59/0x72
           remove_files+0x61/0x96
           sysfs_remove_group+0x81/0xa4
           sysfs_remove_groups+0x3b/0x44
           kobject_del+0x44/0x94
           blk_mq_unregister_dev+0x83/0xdd
           blk_unregister_queue+0xa0/0x10b
           del_gendisk+0x259/0x3fa
           null_del_dev+0x8b/0x1c3 [null_blk]
           null_exit+0x5c/0x95 [null_blk]
           __se_sys_delete_module+0x204/0x337
           do_syscall_64+0xa7/0x295
           entry_SYSCALL_64_after_hwframe+0x49/0xbe

    other info that might help us debug this:

     Possible unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
      lock(&q->sysfs_lock);
                                   lock(kn->count#202);
                                   lock(&q->sysfs_lock);
      lock(kn->count#202);

     *** DEADLOCK ***

    2 locks held by rmmod/777:
     #0: 00000000e69bd9de (&lock){+.+.}, at: null_exit+0x2e/0x95 [null_blk]
     #1: 00000000fb16ae21 (&q->sysfs_lock){+.+.}, at: blk_unregister_queue+0x78/0x10b

    stack backtrace:
    CPU: 0 PID: 777 Comm: rmmod Not tainted 5.3.0-rc3-00044-g73277fc75ea0 #1380
    Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS ?-20180724_192412-buildhw-07.phx4
    Call Trace:
     dump_stack+0x9a/0xe6
     check_noncircular+0x207/0x251
     ? print_circular_bug+0x32a/0x32a
     ? find_usage_backwards+0x84/0xb0
     check_prev_add+0x5d2/0xc45
     validate_chain+0xed3/0xf94
     ? check_prev_add+0xc45/0xc45
     ? mark_lock+0x11b/0x804
     ? check_usage_forwards+0x1ca/0x1ca
     __lock_acquire+0x95f/0xa2f
     lock_acquire+0x1b4/0x1e8
     ? kernfs_remove_by_name_ns+0x59/0x72
     __kernfs_remove+0x237/0x40b
     ? kernfs_remove_by_name_ns+0x59/0x72
     ? kernfs_next_descendant_post+0x7d/0x7d
     ? strlen+0x10/0x23
     ? strcmp+0x22/0x44
     kernfs_remove_by_name_ns+0x59/0x72
     remove_files+0x61/0x96
     sysfs_remove_group+0x81/0xa4
     sysfs_remove_groups+0x3b/0x44
     kobject_del+0x44/0x94
     blk_mq_unregister_dev+0x83/0xdd
     blk_unregister_queue+0xa0/0x10b
     del_gendisk+0x259/0x3fa
     ? disk_events_poll_msecs_store+0x12b/0x12b
     ? check_flags+0x1ea/0x204
     ? mark_held_locks+0x1f/0x7a
     null_del_dev+0x8b/0x1c3 [null_blk]
     null_exit+0x5c/0x95 [null_blk]
     __se_sys_delete_module+0x204/0x337
     ? free_module+0x39f/0x39f
     ? blkcg_maybe_throttle_current+0x8a/0x718
     ? rwlock_bug+0x62/0x62
     ? __blkcg_punt_bio_submit+0xd0/0xd0
     ? trace_hardirqs_on_thunk+0x1a/0x20
     ? mark_held_locks+0x1f/0x7a
     ? do_syscall_64+0x4c/0x295
     do_syscall_64+0xa7/0x295
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x7fb696cdbe6b
    Code: 73 01 c3 48 8b 0d 1d 20 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 008
    RSP: 002b:00007ffec9588788 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
    RAX: ffffffffffffffda RBX: 0000559e589137c0 RCX: 00007fb696cdbe6b
    RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559e58913828
    RBP: 0000000000000000 R08: 00007ffec9587701 R09: 0000000000000000
    R10: 00007fb696d4eae0 R11: 0000000000000206 R12: 00007ffec95889b0
    R13: 00007ffec95896b3 R14: 0000559e58913260 R15: 0000559e589137c0

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27 10:40:20 -06:00

1070 lines
26 KiB
C

// 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/blk-mq.h>
#include <linux/blk-cgroup.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-debugfs.h"
#include "blk-wbt.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_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_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 = q->backing_dev_info->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 = queue_var_store(&ra_kb, page, count);
if (ret < 0)
return ret;
q->backing_dev_info->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_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;
ssize_t ret = queue_var_store(&max_discard, page, count);
if (ret < 0)
return ret;
if (max_discard & (q->limits.discard_granularity - 1))
return -EINVAL;
max_discard >>= 9;
if (max_discard > UINT_MAX)
return -EINVAL;
if (max_discard > q->limits.max_hw_discard_sectors)
max_discard = q->limits.max_hw_discard_sectors;
q->limits.max_discard_sectors = max_discard;
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 sprintf(page, "%llu\n",
(unsigned long long)q->limits.max_write_same_sectors << 9);
}
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_max_sectors_store(struct request_queue *q, const char *page, size_t count)
{
unsigned long max_sectors_kb,
max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1,
page_kb = 1 << (PAGE_SHIFT - 10);
ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
if (ret < 0)
return ret;
max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb, (unsigned long)
q->limits.max_dev_sectors >> 1);
if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
return -EINVAL;
spin_lock_irq(&q->queue_lock);
q->limits.max_sectors = max_sectors_kb << 1;
q->backing_dev_info->io_pages = max_sectors_kb >> (PAGE_SHIFT - 10);
spin_unlock_irq(&q->queue_lock);
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));
}
#define QUEUE_SYSFS_BIT_FNS(name, flag, neg) \
static ssize_t \
queue_show_##name(struct request_queue *q, char *page) \
{ \
int bit; \
bit = test_bit(QUEUE_FLAG_##flag, &q->queue_flags); \
return queue_var_show(neg ? !bit : bit, page); \
} \
static ssize_t \
queue_store_##name(struct request_queue *q, const char *page, size_t count) \
{ \
unsigned long val; \
ssize_t ret; \
ret = queue_var_store(&val, page, count); \
if (ret < 0) \
return ret; \
if (neg) \
val = !val; \
\
if (val) \
blk_queue_flag_set(QUEUE_FLAG_##flag, q); \
else \
blk_queue_flag_clear(QUEUE_FLAG_##flag, q); \
return ret; \
}
QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1);
QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
#undef QUEUE_SYSFS_BIT_FNS
static ssize_t queue_zoned_show(struct request_queue *q, char *page)
{
switch (blk_queue_zoned_model(q)) {
case BLK_ZONED_HA:
return sprintf(page, "host-aware\n");
case BLK_ZONED_HM:
return sprintf(page, "host-managed\n");
default:
return sprintf(page, "none\n");
}
}
static ssize_t queue_nr_zones_show(struct request_queue *q, char *page)
{
return queue_var_show(blk_queue_nr_zones(q), 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)
{
int val;
if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
val = BLK_MQ_POLL_CLASSIC;
else
val = q->poll_nsec / 1000;
return sprintf(page, "%d\n", val);
}
static ssize_t queue_poll_delay_store(struct request_queue *q, const char *page,
size_t count)
{
int err, val;
if (!q->mq_ops || !q->mq_ops->poll)
return -EINVAL;
err = kstrtoint(page, 10, &val);
if (err < 0)
return err;
if (val == BLK_MQ_POLL_CLASSIC)
q->poll_nsec = BLK_MQ_POLL_CLASSIC;
else if (val >= 0)
q->poll_nsec = val * 1000;
else
return -EINVAL;
return count;
}
static ssize_t queue_poll_show(struct request_queue *q, char *page)
{
return queue_var_show(test_bit(QUEUE_FLAG_POLL, &q->queue_flags), page);
}
static ssize_t queue_poll_store(struct request_queue *q, const char *page,
size_t count)
{
unsigned long poll_on;
ssize_t ret;
if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL ||
!q->tag_set->map[HCTX_TYPE_POLL].nr_queues)
return -EINVAL;
ret = queue_var_store(&poll_on, page, count);
if (ret < 0)
return ret;
if (poll_on)
blk_queue_flag_set(QUEUE_FLAG_POLL, q);
else
blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
return ret;
}
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_wb_lat_show(struct request_queue *q, char *page)
{
if (!wbt_rq_qos(q))
return -EINVAL;
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);
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_freeze_queue(q);
blk_mq_quiesce_queue(q);
wbt_set_min_lat(q, val);
wbt_update_limits(q);
blk_mq_unquiesce_queue(q);
blk_mq_unfreeze_queue(q);
return count;
}
static ssize_t queue_wc_show(struct request_queue *q, char *page)
{
if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
return sprintf(page, "write back\n");
return sprintf(page, "write through\n");
}
static ssize_t queue_wc_store(struct request_queue *q, const char *page,
size_t count)
{
int set = -1;
if (!strncmp(page, "write back", 10))
set = 1;
else if (!strncmp(page, "write through", 13) ||
!strncmp(page, "none", 4))
set = 0;
if (set == -1)
return -EINVAL;
if (set)
blk_queue_flag_set(QUEUE_FLAG_WC, q);
else
blk_queue_flag_clear(QUEUE_FLAG_WC, q);
return count;
}
static ssize_t queue_fua_show(struct request_queue *q, char *page)
{
return sprintf(page, "%u\n", test_bit(QUEUE_FLAG_FUA, &q->queue_flags));
}
static ssize_t queue_dax_show(struct request_queue *q, char *page)
{
return queue_var_show(blk_queue_dax(q), page);
}
static struct queue_sysfs_entry queue_requests_entry = {
.attr = {.name = "nr_requests", .mode = 0644 },
.show = queue_requests_show,
.store = queue_requests_store,
};
static struct queue_sysfs_entry queue_ra_entry = {
.attr = {.name = "read_ahead_kb", .mode = 0644 },
.show = queue_ra_show,
.store = queue_ra_store,
};
static struct queue_sysfs_entry queue_max_sectors_entry = {
.attr = {.name = "max_sectors_kb", .mode = 0644 },
.show = queue_max_sectors_show,
.store = queue_max_sectors_store,
};
static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
.attr = {.name = "max_hw_sectors_kb", .mode = 0444 },
.show = queue_max_hw_sectors_show,
};
static struct queue_sysfs_entry queue_max_segments_entry = {
.attr = {.name = "max_segments", .mode = 0444 },
.show = queue_max_segments_show,
};
static struct queue_sysfs_entry queue_max_discard_segments_entry = {
.attr = {.name = "max_discard_segments", .mode = 0444 },
.show = queue_max_discard_segments_show,
};
static struct queue_sysfs_entry queue_max_integrity_segments_entry = {
.attr = {.name = "max_integrity_segments", .mode = 0444 },
.show = queue_max_integrity_segments_show,
};
static struct queue_sysfs_entry queue_max_segment_size_entry = {
.attr = {.name = "max_segment_size", .mode = 0444 },
.show = queue_max_segment_size_show,
};
static struct queue_sysfs_entry queue_iosched_entry = {
.attr = {.name = "scheduler", .mode = 0644 },
.show = elv_iosched_show,
.store = elv_iosched_store,
};
static struct queue_sysfs_entry queue_hw_sector_size_entry = {
.attr = {.name = "hw_sector_size", .mode = 0444 },
.show = queue_logical_block_size_show,
};
static struct queue_sysfs_entry queue_logical_block_size_entry = {
.attr = {.name = "logical_block_size", .mode = 0444 },
.show = queue_logical_block_size_show,
};
static struct queue_sysfs_entry queue_physical_block_size_entry = {
.attr = {.name = "physical_block_size", .mode = 0444 },
.show = queue_physical_block_size_show,
};
static struct queue_sysfs_entry queue_chunk_sectors_entry = {
.attr = {.name = "chunk_sectors", .mode = 0444 },
.show = queue_chunk_sectors_show,
};
static struct queue_sysfs_entry queue_io_min_entry = {
.attr = {.name = "minimum_io_size", .mode = 0444 },
.show = queue_io_min_show,
};
static struct queue_sysfs_entry queue_io_opt_entry = {
.attr = {.name = "optimal_io_size", .mode = 0444 },
.show = queue_io_opt_show,
};
static struct queue_sysfs_entry queue_discard_granularity_entry = {
.attr = {.name = "discard_granularity", .mode = 0444 },
.show = queue_discard_granularity_show,
};
static struct queue_sysfs_entry queue_discard_max_hw_entry = {
.attr = {.name = "discard_max_hw_bytes", .mode = 0444 },
.show = queue_discard_max_hw_show,
};
static struct queue_sysfs_entry queue_discard_max_entry = {
.attr = {.name = "discard_max_bytes", .mode = 0644 },
.show = queue_discard_max_show,
.store = queue_discard_max_store,
};
static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
.attr = {.name = "discard_zeroes_data", .mode = 0444 },
.show = queue_discard_zeroes_data_show,
};
static struct queue_sysfs_entry queue_write_same_max_entry = {
.attr = {.name = "write_same_max_bytes", .mode = 0444 },
.show = queue_write_same_max_show,
};
static struct queue_sysfs_entry queue_write_zeroes_max_entry = {
.attr = {.name = "write_zeroes_max_bytes", .mode = 0444 },
.show = queue_write_zeroes_max_show,
};
static struct queue_sysfs_entry queue_nonrot_entry = {
.attr = {.name = "rotational", .mode = 0644 },
.show = queue_show_nonrot,
.store = queue_store_nonrot,
};
static struct queue_sysfs_entry queue_zoned_entry = {
.attr = {.name = "zoned", .mode = 0444 },
.show = queue_zoned_show,
};
static struct queue_sysfs_entry queue_nr_zones_entry = {
.attr = {.name = "nr_zones", .mode = 0444 },
.show = queue_nr_zones_show,
};
static struct queue_sysfs_entry queue_nomerges_entry = {
.attr = {.name = "nomerges", .mode = 0644 },
.show = queue_nomerges_show,
.store = queue_nomerges_store,
};
static struct queue_sysfs_entry queue_rq_affinity_entry = {
.attr = {.name = "rq_affinity", .mode = 0644 },
.show = queue_rq_affinity_show,
.store = queue_rq_affinity_store,
};
static struct queue_sysfs_entry queue_iostats_entry = {
.attr = {.name = "iostats", .mode = 0644 },
.show = queue_show_iostats,
.store = queue_store_iostats,
};
static struct queue_sysfs_entry queue_random_entry = {
.attr = {.name = "add_random", .mode = 0644 },
.show = queue_show_random,
.store = queue_store_random,
};
static struct queue_sysfs_entry queue_poll_entry = {
.attr = {.name = "io_poll", .mode = 0644 },
.show = queue_poll_show,
.store = queue_poll_store,
};
static struct queue_sysfs_entry queue_poll_delay_entry = {
.attr = {.name = "io_poll_delay", .mode = 0644 },
.show = queue_poll_delay_show,
.store = queue_poll_delay_store,
};
static struct queue_sysfs_entry queue_wc_entry = {
.attr = {.name = "write_cache", .mode = 0644 },
.show = queue_wc_show,
.store = queue_wc_store,
};
static struct queue_sysfs_entry queue_fua_entry = {
.attr = {.name = "fua", .mode = 0444 },
.show = queue_fua_show,
};
static struct queue_sysfs_entry queue_dax_entry = {
.attr = {.name = "dax", .mode = 0444 },
.show = queue_dax_show,
};
static struct queue_sysfs_entry queue_io_timeout_entry = {
.attr = {.name = "io_timeout", .mode = 0644 },
.show = queue_io_timeout_show,
.store = queue_io_timeout_store,
};
static struct queue_sysfs_entry queue_wb_lat_entry = {
.attr = {.name = "wbt_lat_usec", .mode = 0644 },
.show = queue_wb_lat_show,
.store = queue_wb_lat_store,
};
#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
static struct queue_sysfs_entry throtl_sample_time_entry = {
.attr = {.name = "throttle_sample_time", .mode = 0644 },
.show = blk_throtl_sample_time_show,
.store = blk_throtl_sample_time_store,
};
#endif
static struct attribute *queue_attrs[] = {
&queue_requests_entry.attr,
&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_iosched_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_write_same_max_entry.attr,
&queue_write_zeroes_max_entry.attr,
&queue_nonrot_entry.attr,
&queue_zoned_entry.attr,
&queue_nr_zones_entry.attr,
&queue_nomerges_entry.attr,
&queue_rq_affinity_entry.attr,
&queue_iostats_entry.attr,
&queue_random_entry.attr,
&queue_poll_entry.attr,
&queue_wc_entry.attr,
&queue_fua_entry.attr,
&queue_dax_entry.attr,
&queue_wb_lat_entry.attr,
&queue_poll_delay_entry.attr,
&queue_io_timeout_entry.attr,
#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
&throtl_sample_time_entry.attr,
#endif
NULL,
};
static umode_t queue_attr_visible(struct kobject *kobj, struct attribute *attr,
int n)
{
struct request_queue *q =
container_of(kobj, struct request_queue, kobj);
if (attr == &queue_io_timeout_entry.attr &&
(!q->mq_ops || !q->mq_ops->timeout))
return 0;
return attr->mode;
}
static struct attribute_group queue_attr_group = {
.attrs = queue_attrs,
.is_visible = 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 request_queue *q =
container_of(kobj, struct request_queue, kobj);
ssize_t res;
if (!entry->show)
return -EIO;
mutex_lock(&q->sysfs_lock);
if (blk_queue_dying(q)) {
mutex_unlock(&q->sysfs_lock);
return -ENOENT;
}
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 request_queue *q;
ssize_t res;
if (!entry->store)
return -EIO;
q = container_of(kobj, struct request_queue, kobj);
mutex_lock(&q->sysfs_lock);
if (blk_queue_dying(q)) {
mutex_unlock(&q->sysfs_lock);
return -ENOENT;
}
res = entry->store(q, page, length);
mutex_unlock(&q->sysfs_lock);
return res;
}
static void blk_free_queue_rcu(struct rcu_head *rcu_head)
{
struct request_queue *q = container_of(rcu_head, struct request_queue,
rcu_head);
kmem_cache_free(blk_requestq_cachep, q);
}
/* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
static void blk_exit_queue(struct request_queue *q)
{
/*
* Since the I/O scheduler exit code may access cgroup information,
* perform I/O scheduler exit before disassociating from the block
* cgroup controller.
*/
if (q->elevator) {
ioc_clear_queue(q);
__elevator_exit(q, q->elevator);
q->elevator = NULL;
}
/*
* Remove all references to @q from the block cgroup controller before
* restoring @q->queue_lock to avoid that restoring this pointer causes
* e.g. blkcg_print_blkgs() to crash.
*/
blkcg_exit_queue(q);
/*
* Since the cgroup code may dereference the @q->backing_dev_info
* pointer, only decrease its reference count after having removed the
* association with the block cgroup controller.
*/
bdi_put(q->backing_dev_info);
}
/**
* __blk_release_queue - release a request queue
* @work: pointer to the release_work member of the request queue to be released
*
* Description:
* This function is called when a block device is being unregistered. The
* process of releasing a request queue starts with blk_cleanup_queue, which
* set the appropriate flags and then calls blk_put_queue, that decrements
* the reference counter of the request queue. Once the reference counter
* of the request queue reaches zero, blk_release_queue is called to release
* all allocated resources of the request queue.
*/
static void __blk_release_queue(struct work_struct *work)
{
struct request_queue *q = container_of(work, typeof(*q), release_work);
if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
blk_stat_remove_callback(q, q->poll_cb);
blk_stat_free_callback(q->poll_cb);
blk_free_queue_stats(q->stats);
blk_exit_queue(q);
blk_queue_free_zone_bitmaps(q);
if (queue_is_mq(q))
blk_mq_release(q);
blk_trace_shutdown(q);
if (queue_is_mq(q))
blk_mq_debugfs_unregister(q);
bioset_exit(&q->bio_split);
ida_simple_remove(&blk_queue_ida, q->id);
call_rcu(&q->rcu_head, blk_free_queue_rcu);
}
static void blk_release_queue(struct kobject *kobj)
{
struct request_queue *q =
container_of(kobj, struct request_queue, kobj);
INIT_WORK(&q->release_work, __blk_release_queue);
schedule_work(&q->release_work);
}
static const struct sysfs_ops queue_sysfs_ops = {
.show = queue_attr_show,
.store = queue_attr_store,
};
struct kobj_type blk_queue_ktype = {
.sysfs_ops = &queue_sysfs_ops,
.release = blk_release_queue,
};
/**
* 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)
{
int ret;
struct device *dev = disk_to_dev(disk);
struct request_queue *q = disk->queue;
bool has_elevator = false;
if (WARN_ON(!q))
return -ENXIO;
WARN_ONCE(blk_queue_registered(q),
"%s is registering an already registered queue\n",
kobject_name(&dev->kobj));
/*
* 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);
}
ret = blk_trace_init_sysfs(dev);
if (ret)
return ret;
mutex_lock(&q->sysfs_dir_lock);
ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
if (ret < 0) {
blk_trace_remove_sysfs(dev);
goto unlock;
}
ret = sysfs_create_group(&q->kobj, &queue_attr_group);
if (ret) {
blk_trace_remove_sysfs(dev);
kobject_del(&q->kobj);
kobject_put(&dev->kobj);
goto unlock;
}
if (queue_is_mq(q)) {
__blk_mq_register_dev(dev, q);
blk_mq_debugfs_register(q);
}
/*
* The flag of QUEUE_FLAG_REGISTERED isn't set yet, so elevator
* switch won't happen at all.
*/
if (q->elevator) {
ret = elv_register_queue(q, false);
if (ret) {
mutex_unlock(&q->sysfs_dir_lock);
kobject_del(&q->kobj);
blk_trace_remove_sysfs(dev);
kobject_put(&dev->kobj);
return ret;
}
has_elevator = true;
}
mutex_lock(&q->sysfs_lock);
blk_queue_flag_set(QUEUE_FLAG_REGISTERED, q);
wbt_enable_default(q);
blk_throtl_register_queue(q);
/* Now everything is ready and send out KOBJ_ADD uevent */
kobject_uevent(&q->kobj, KOBJ_ADD);
if (has_elevator)
kobject_uevent(&q->elevator->kobj, KOBJ_ADD);
mutex_unlock(&q->sysfs_lock);
ret = 0;
unlock:
mutex_unlock(&q->sysfs_dir_lock);
return ret;
}
EXPORT_SYMBOL_GPL(blk_register_queue);
/**
* 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;
bool has_elevator;
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);
has_elevator = !!q->elevator;
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_unregister_dev(disk_to_dev(disk), q);
kobject_uevent(&q->kobj, KOBJ_REMOVE);
kobject_del(&q->kobj);
blk_trace_remove_sysfs(disk_to_dev(disk));
if (has_elevator)
elv_unregister_queue(q);
mutex_unlock(&q->sysfs_dir_lock);
kobject_put(&disk_to_dev(disk)->kobj);
}