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dm: add statistics support

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Support the collection of I/O statistics on user-defined regions of
a DM device.  If no regions are defined no statistics are collected so
there isn't any performance impact.  Only bio-based DM devices are
currently supported.

Each user-defined region specifies a starting sector, length and step.
Individual statistics will be collected for each step-sized area within
the range specified.

The I/O statistics counters for each step-sized area of a region are
in the same format as /sys/block/*/stat or /proc/diskstats but extra
counters (12 and 13) are provided: total time spent reading and
writing in milliseconds.  All these counters may be accessed by sending
the @stats_print message to the appropriate DM device via dmsetup.

The creation of DM statistics will allocate memory via kmalloc or
fallback to using vmalloc space.  At most, 1/4 of the overall system
memory may be allocated by DM statistics.  The admin can see how much
memory is used by reading
/sys/module/dm_mod/parameters/stats_current_allocated_bytes

See Documentation/device-mapper/statistics.txt for more details.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mikulas Patocka 2013-08-16 10:54:23 -04:00 committed by Mike Snitzer
parent 94563badaf
commit fd2ed4d252
9 changed files with 1299 additions and 14 deletions
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186
Documentation/device-mapper/statistics.txt Normal file
View file

@ -0,0 +1,186 @@
DM statistics
=============
Device Mapper supports the collection of I/O statistics on user-defined
regions of a DM device. If no regions are defined no statistics are
collected so there isn't any performance impact. Only bio-based DM
devices are currently supported.
Each user-defined region specifies a starting sector, length and step.
Individual statistics will be collected for each step-sized area within
the range specified.
The I/O statistics counters for each step-sized area of a region are
in the same format as /sys/block/*/stat or /proc/diskstats (see:
Documentation/iostats.txt). But two extra counters (12 and 13) are
provided: total time spent reading and writing in milliseconds. All
these counters may be accessed by sending the @stats_print message to
the appropriate DM device via dmsetup.
Each region has a corresponding unique identifier, which we call a
region_id, that is assigned when the region is created. The region_id
must be supplied when querying statistics about the region, deleting the
region, etc. Unique region_ids enable multiple userspace programs to
request and process statistics for the same DM device without stepping
on each other's data.
The creation of DM statistics will allocate memory via kmalloc or
fallback to using vmalloc space. At most, 1/4 of the overall system
memory may be allocated by DM statistics. The admin can see how much
memory is used by reading
/sys/module/dm_mod/parameters/stats_current_allocated_bytes
Messages
========
@stats_create <range> <step> [<program_id> [<aux_data>]]
Create a new region and return the region_id.
<range>
"-" - whole device
"<start_sector>+<length>" - a range of <length> 512-byte sectors
starting with <start_sector>.
<step>
"<area_size>" - the range is subdivided into areas each containing
<area_size> sectors.
"/<number_of_areas>" - the range is subdivided into the specified
number of areas.
<program_id>
An optional parameter. A name that uniquely identifies
the userspace owner of the range. This groups ranges together
so that userspace programs can identify the ranges they
created and ignore those created by others.
The kernel returns this string back in the output of
@stats_list message, but it doesn't use it for anything else.
<aux_data>
An optional parameter. A word that provides auxiliary data
that is useful to the client program that created the range.
The kernel returns this string back in the output of
@stats_list message, but it doesn't use this value for anything.
@stats_delete <region_id>
Delete the region with the specified id.
<region_id>
region_id returned from @stats_create
@stats_clear <region_id>
Clear all the counters except the in-flight i/o counters.
<region_id>
region_id returned from @stats_create
@stats_list [<program_id>]
List all regions registered with @stats_create.
<program_id>
An optional parameter.
If this parameter is specified, only matching regions
are returned.
If it is not specified, all regions are returned.
Output format:
<region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
@stats_print <region_id> [<starting_line> <number_of_lines>]
Print counters for each step-sized area of a region.
<region_id>
region_id returned from @stats_create
<starting_line>
The index of the starting line in the output.
If omitted, all lines are returned.
<number_of_lines>
The number of lines to include in the output.
If omitted, all lines are returned.
Output format for each step-sized area of a region:
<start_sector>+<length> counters
The first 11 counters have the same meaning as
/sys/block/*/stat or /proc/diskstats.
Please refer to Documentation/iostats.txt for details.
1. the number of reads completed
2. the number of reads merged
3. the number of sectors read
4. the number of milliseconds spent reading
5. the number of writes completed
6. the number of writes merged
7. the number of sectors written
8. the number of milliseconds spent writing
9. the number of I/Os currently in progress
10. the number of milliseconds spent doing I/Os
11. the weighted number of milliseconds spent doing I/Os
Additional counters:
12. the total time spent reading in milliseconds
13. the total time spent writing in milliseconds
@stats_print_clear <region_id> [<starting_line> <number_of_lines>]
Atomically print and then clear all the counters except the
in-flight i/o counters. Useful when the client consuming the
statistics does not want to lose any statistics (those updated
between printing and clearing).
<region_id>
region_id returned from @stats_create
<starting_line>
The index of the starting line in the output.
If omitted, all lines are printed and then cleared.
<number_of_lines>
The number of lines to process.
If omitted, all lines are printed and then cleared.
@stats_set_aux <region_id> <aux_data>
Store auxiliary data aux_data for the specified region.
<region_id>
region_id returned from @stats_create
<aux_data>
The string that identifies data which is useful to the client
program that created the range. The kernel returns this
string back in the output of @stats_list message, but it
doesn't use this value for anything.
Examples
========
Subdivide the DM device 'vol' into 100 pieces and start collecting
statistics on them:
dmsetup message vol 0 @stats_create - /100
Set the auxillary data string to "foo bar baz" (the escape for each
space must also be escaped, otherwise the shell will consume them):
dmsetup message vol 0 @stats_set_aux 0 foo\\ bar\\ baz
List the statistics:
dmsetup message vol 0 @stats_list
Print the statistics:
dmsetup message vol 0 @stats_print 0
Delete the statistics:
dmsetup message vol 0 @stats_delete 0

2
drivers/md/Makefile
View file

@ -3,7 +3,7 @@
#
dm-mod-y += dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o
dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o
dm-multipath-y += dm-path-selector.o dm-mpath.o
dm-snapshot-y += dm-snap.o dm-exception-store.o dm-snap-transient.o \
dm-snap-persistent.o

22
drivers/md/dm-ioctl.c
View file

@ -1455,20 +1455,26 @@ static int table_status(struct dm_ioctl *param, size_t param_size)
return 0;
}
static bool buffer_test_overflow(char *result, unsigned maxlen)
{
return !maxlen || strlen(result) + 1 >= maxlen;
}
/*
* Process device-mapper dependent messages.
* Process device-mapper dependent messages. Messages prefixed with '@'
* are processed by the DM core. All others are delivered to the target.
* Returns a number <= 1 if message was processed by device mapper.
* Returns 2 if message should be delivered to the target.
*/
static int message_for_md(struct mapped_device *md, unsigned argc, char **argv,
char *result, unsigned maxlen)
{
return 2;
int r;
if (**argv != '@')
return 2; /* no '@' prefix, deliver to target */
r = dm_stats_message(md, argc, argv, result, maxlen);
if (r < 2)
return r;
DMERR("Unsupported message sent to DM core: %s", argv[0]);
return -EINVAL;
}
/*
@ -1542,7 +1548,7 @@ static int target_message(struct dm_ioctl *param, size_t param_size)
if (r == 1) {
param->flags |= DM_DATA_OUT_FLAG;
if (buffer_test_overflow(result, maxlen))
if (dm_message_test_buffer_overflow(result, maxlen))
param->flags |= DM_BUFFER_FULL_FLAG;
else
param->data_size = param->data_start + strlen(result) + 1;

969
drivers/md/dm-stats.c Normal file
View file

@ -0,0 +1,969 @@
#include <linux/errno.h>
#include <linux/numa.h>
#include <linux/slab.h>
#include <linux/rculist.h>
#include <linux/threads.h>
#include <linux/preempt.h>
#include <linux/irqflags.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/device-mapper.h>
#include "dm.h"
#include "dm-stats.h"
#define DM_MSG_PREFIX "stats"
static int dm_stat_need_rcu_barrier;
/*
* Using 64-bit values to avoid overflow (which is a
* problem that block/genhd.c's IO accounting has).
*/
struct dm_stat_percpu {
unsigned long long sectors[2];
unsigned long long ios[2];
unsigned long long merges[2];
unsigned long long ticks[2];
unsigned long long io_ticks[2];
unsigned long long io_ticks_total;
unsigned long long time_in_queue;
};
struct dm_stat_shared {
atomic_t in_flight[2];
unsigned long stamp;
struct dm_stat_percpu tmp;
};
struct dm_stat {
struct list_head list_entry;
int id;
size_t n_entries;
sector_t start;
sector_t end;
sector_t step;
const char *program_id;
const char *aux_data;
struct rcu_head rcu_head;
size_t shared_alloc_size;
size_t percpu_alloc_size;
struct dm_stat_percpu *stat_percpu[NR_CPUS];
struct dm_stat_shared stat_shared[0];
};
struct dm_stats_last_position {
sector_t last_sector;
unsigned last_rw;
};
/*
* A typo on the command line could possibly make the kernel run out of memory
* and crash. To prevent the crash we account all used memory. We fail if we
* exhaust 1/4 of all memory or 1/2 of vmalloc space.
*/
#define DM_STATS_MEMORY_FACTOR 4
#define DM_STATS_VMALLOC_FACTOR 2
static DEFINE_SPINLOCK(shared_memory_lock);
static unsigned long shared_memory_amount;
static bool __check_shared_memory(size_t alloc_size)
{
size_t a;
a = shared_memory_amount + alloc_size;
if (a < shared_memory_amount)
return false;
if (a >> PAGE_SHIFT > totalram_pages / DM_STATS_MEMORY_FACTOR)
return false;
#ifdef CONFIG_MMU
if (a > (VMALLOC_END - VMALLOC_START) / DM_STATS_VMALLOC_FACTOR)
return false;
#endif
return true;
}
static bool check_shared_memory(size_t alloc_size)
{
bool ret;
spin_lock_irq(&shared_memory_lock);
ret = __check_shared_memory(alloc_size);
spin_unlock_irq(&shared_memory_lock);
return ret;
}
static bool claim_shared_memory(size_t alloc_size)
{
spin_lock_irq(&shared_memory_lock);
if (!__check_shared_memory(alloc_size)) {
spin_unlock_irq(&shared_memory_lock);
return false;
}
shared_memory_amount += alloc_size;
spin_unlock_irq(&shared_memory_lock);
return true;
}
static void free_shared_memory(size_t alloc_size)
{
unsigned long flags;
spin_lock_irqsave(&shared_memory_lock, flags);
if (WARN_ON_ONCE(shared_memory_amount < alloc_size)) {
spin_unlock_irqrestore(&shared_memory_lock, flags);
DMCRIT("Memory usage accounting bug.");
return;
}
shared_memory_amount -= alloc_size;
spin_unlock_irqrestore(&shared_memory_lock, flags);
}
static void *dm_kvzalloc(size_t alloc_size, int node)
{
void *p;
if (!claim_shared_memory(alloc_size))
return NULL;
if (alloc_size <= KMALLOC_MAX_SIZE) {
p = kzalloc_node(alloc_size, GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN, node);
if (p)
return p;
}
p = vzalloc_node(alloc_size, node);
if (p)
return p;
free_shared_memory(alloc_size);
return NULL;
}
static void dm_kvfree(void *ptr, size_t alloc_size)
{
if (!ptr)
return;
free_shared_memory(alloc_size);
if (is_vmalloc_addr(ptr))
vfree(ptr);
else
kfree(ptr);
}
static void dm_stat_free(struct rcu_head *head)
{
int cpu;
struct dm_stat *s = container_of(head, struct dm_stat, rcu_head);
kfree(s->program_id);
kfree(s->aux_data);
for_each_possible_cpu(cpu)
dm_kvfree(s->stat_percpu[cpu], s->percpu_alloc_size);
dm_kvfree(s, s->shared_alloc_size);
}
static int dm_stat_in_flight(struct dm_stat_shared *shared)
{
return atomic_read(&shared->in_flight[READ]) +
atomic_read(&shared->in_flight[WRITE]);
}
void dm_stats_init(struct dm_stats *stats)
{
int cpu;
struct dm_stats_last_position *last;
mutex_init(&stats->mutex);
INIT_LIST_HEAD(&stats->list);
stats->last = alloc_percpu(struct dm_stats_last_position);
for_each_possible_cpu(cpu) {
last = per_cpu_ptr(stats->last, cpu);
last->last_sector = (sector_t)ULLONG_MAX;
last->last_rw = UINT_MAX;
}
}
void dm_stats_cleanup(struct dm_stats *stats)
{
size_t ni;
struct dm_stat *s;
struct dm_stat_shared *shared;
while (!list_empty(&stats->list)) {
s = container_of(stats->list.next, struct dm_stat, list_entry);
list_del(&s->list_entry);
for (ni = 0; ni < s->n_entries; ni++) {
shared = &s->stat_shared[ni];
if (WARN_ON(dm_stat_in_flight(shared))) {
DMCRIT("leaked in-flight counter at index %lu "
"(start %llu, end %llu, step %llu): reads %d, writes %d",
(unsigned long)ni,
(unsigned long long)s->start,
(unsigned long long)s->end,
(unsigned long long)s->step,
atomic_read(&shared->in_flight[READ]),
atomic_read(&shared->in_flight[WRITE]));
}
}
dm_stat_free(&s->rcu_head);
}
free_percpu(stats->last);
}
static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end,
sector_t step, const char *program_id, const char *aux_data,
void (*suspend_callback)(struct mapped_device *),
void (*resume_callback)(struct mapped_device *),
struct mapped_device *md)
{
struct list_head *l;
struct dm_stat *s, *tmp_s;
sector_t n_entries;
size_t ni;
size_t shared_alloc_size;
size_t percpu_alloc_size;
struct dm_stat_percpu *p;
int cpu;
int ret_id;
int r;
if (end < start || !step)
return -EINVAL;
n_entries = end - start;
if (dm_sector_div64(n_entries, step))
n_entries++;
if (n_entries != (size_t)n_entries || !(size_t)(n_entries + 1))
return -EOVERFLOW;
shared_alloc_size = sizeof(struct dm_stat) + (size_t)n_entries * sizeof(struct dm_stat_shared);
if ((shared_alloc_size - sizeof(struct dm_stat)) / sizeof(struct dm_stat_shared) != n_entries)
return -EOVERFLOW;
percpu_alloc_size = (size_t)n_entries * sizeof(struct dm_stat_percpu);
if (percpu_alloc_size / sizeof(struct dm_stat_percpu) != n_entries)
return -EOVERFLOW;
if (!check_shared_memory(shared_alloc_size + num_possible_cpus() * percpu_alloc_size))
return -ENOMEM;
s = dm_kvzalloc(shared_alloc_size, NUMA_NO_NODE);
if (!s)
return -ENOMEM;
s->n_entries = n_entries;
s->start = start;
s->end = end;
s->step = step;
s->shared_alloc_size = shared_alloc_size;
s->percpu_alloc_size = percpu_alloc_size;
s->program_id = kstrdup(program_id, GFP_KERNEL);
if (!s->program_id) {
r = -ENOMEM;
goto out;
}
s->aux_data = kstrdup(aux_data, GFP_KERNEL);
if (!s->aux_data) {
r = -ENOMEM;
goto out;
}
for (ni = 0; ni < n_entries; ni++) {
atomic_set(&s->stat_shared[ni].in_flight[READ], 0);
atomic_set(&s->stat_shared[ni].in_flight[WRITE], 0);
}
for_each_possible_cpu(cpu) {
p = dm_kvzalloc(percpu_alloc_size, cpu_to_node(cpu));
if (!p) {
r = -ENOMEM;
goto out;
}
s->stat_percpu[cpu] = p;
}
/*
* Suspend/resume to make sure there is no i/o in flight,
* so that newly created statistics will be exact.
*
* (note: we couldn't suspend earlier because we must not
* allocate memory while suspended)
*/
suspend_callback(md);
mutex_lock(&stats->mutex);
s->id = 0;
list_for_each(l, &stats->list) {
tmp_s = container_of(l, struct dm_stat, list_entry);
if (WARN_ON(tmp_s->id < s->id)) {
r = -EINVAL;
goto out_unlock_resume;
}
if (tmp_s->id > s->id)
break;
if (unlikely(s->id == INT_MAX)) {
r = -ENFILE;
goto out_unlock_resume;
}
s->id++;
}
ret_id = s->id;
list_add_tail_rcu(&s->list_entry, l);
mutex_unlock(&stats->mutex);
resume_callback(md);
return ret_id;
out_unlock_resume:
mutex_unlock(&stats->mutex);
resume_callback(md);
out:
dm_stat_free(&s->rcu_head);
return r;
}
static struct dm_stat *__dm_stats_find(struct dm_stats *stats, int id)
{
struct dm_stat *s;
list_for_each_entry(s, &stats->list, list_entry) {
if (s->id > id)
break;
if (s->id == id)
return s;
}
return NULL;
}
static int dm_stats_delete(struct dm_stats *stats, int id)
{
struct dm_stat *s;
int cpu;
mutex_lock(&stats->mutex);
s = __dm_stats_find(stats, id);
if (!s) {
mutex_unlock(&stats->mutex);
return -ENOENT;
}
list_del_rcu(&s->list_entry);
mutex_unlock(&stats->mutex);
/*
* vfree can't be called from RCU callback
*/
for_each_possible_cpu(cpu)
if (is_vmalloc_addr(s->stat_percpu))
goto do_sync_free;
if (is_vmalloc_addr(s)) {
do_sync_free:
synchronize_rcu_expedited();
dm_stat_free(&s->rcu_head);
} else {
ACCESS_ONCE(dm_stat_need_rcu_barrier) = 1;
call_rcu(&s->rcu_head, dm_stat_free);
}
return 0;
}
static int dm_stats_list(struct dm_stats *stats, const char *program,
char *result, unsigned maxlen)
{
struct dm_stat *s;
sector_t len;
unsigned sz = 0;
/*
* Output format:
* <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
*/
mutex_lock(&stats->mutex);
list_for_each_entry(s, &stats->list, list_entry) {
if (!program || !strcmp(program, s->program_id)) {
len = s->end - s->start;
DMEMIT("%d: %llu+%llu %llu %s %s\n", s->id,
(unsigned long long)s->start,
(unsigned long long)len,
(unsigned long long)s->step,
s->program_id,
s->aux_data);
}
}
mutex_unlock(&stats->mutex);
return 1;
}
static void dm_stat_round(struct dm_stat_shared *shared, struct dm_stat_percpu *p)
{
/*
* This is racy, but so is part_round_stats_single.
*/
unsigned long now = jiffies;
unsigned in_flight_read;
unsigned in_flight_write;
unsigned long difference = now - shared->stamp;
if (!difference)
return;
in_flight_read = (unsigned)atomic_read(&shared->in_flight[READ]);
in_flight_write = (unsigned)atomic_read(&shared->in_flight[WRITE]);
if (in_flight_read)
p->io_ticks[READ] += difference;
if (in_flight_write)
p->io_ticks[WRITE] += difference;
if (in_flight_read + in_flight_write) {
p->io_ticks_total += difference;
p->time_in_queue += (in_flight_read + in_flight_write) * difference;
}
shared->stamp = now;
}
static void dm_stat_for_entry(struct dm_stat *s, size_t entry,
unsigned long bi_rw, sector_t len, bool merged,
bool end, unsigned long duration)
{
unsigned long idx = bi_rw & REQ_WRITE;
struct dm_stat_shared *shared = &s->stat_shared[entry];
struct dm_stat_percpu *p;
/*
* For strict correctness we should use local_irq_disable/enable
* instead of preempt_disable/enable.
*
* This is racy if the driver finishes bios from non-interrupt
* context as well as from interrupt context or from more different
* interrupts.
*
* However, the race only results in not counting some events,
* so it is acceptable.
*
* part_stat_lock()/part_stat_unlock() have this race too.
*/
preempt_disable();
p = &s->stat_percpu[smp_processor_id()][entry];
if (!end) {
dm_stat_round(shared, p);
atomic_inc(&shared->in_flight[idx]);
} else {
dm_stat_round(shared, p);
atomic_dec(&shared->in_flight[idx]);
p->sectors[idx] += len;
p->ios[idx] += 1;
p->merges[idx] += merged;
p->ticks[idx] += duration;
}
preempt_enable();
}
static void __dm_stat_bio(struct dm_stat *s, unsigned long bi_rw,
sector_t bi_sector, sector_t end_sector,
bool end, unsigned long duration,
struct dm_stats_aux *stats_aux)
{
sector_t rel_sector, offset, todo, fragment_len;
size_t entry;
if (end_sector <= s->start || bi_sector >= s->end)
return;
if (unlikely(bi_sector < s->start)) {
rel_sector = 0;
todo = end_sector - s->start;
} else {
rel_sector = bi_sector - s->start;
todo = end_sector - bi_sector;
}
if (unlikely(end_sector > s->end))
todo -= (end_sector - s->end);
offset = dm_sector_div64(rel_sector, s->step);
entry = rel_sector;
do {
if (WARN_ON_ONCE(entry >= s->n_entries)) {
DMCRIT("Invalid area access in region id %d", s->id);
return;
}
fragment_len = todo;
if (fragment_len > s->step - offset)
fragment_len = s->step - offset;
dm_stat_for_entry(s, entry, bi_rw, fragment_len,
stats_aux->merged, end, duration);
todo -= fragment_len;
entry++;
offset = 0;
} while (unlikely(todo != 0));
}
void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw,
sector_t bi_sector, unsigned bi_sectors, bool end,
unsigned long duration, struct dm_stats_aux *stats_aux)
{
struct dm_stat *s;
sector_t end_sector;
struct dm_stats_last_position *last;
if (unlikely(!bi_sectors))
return;
end_sector = bi_sector + bi_sectors;
if (!end) {
/*
* A race condition can at worst result in the merged flag being
* misrepresented, so we don't have to disable preemption here.
*/
last = __this_cpu_ptr(stats->last);
stats_aux->merged =
(bi_sector == (ACCESS_ONCE(last->last_sector) &&
((bi_rw & (REQ_WRITE | REQ_DISCARD)) ==
(ACCESS_ONCE(last->last_rw) & (REQ_WRITE | REQ_DISCARD)))
));
ACCESS_ONCE(last->last_sector) = end_sector;
ACCESS_ONCE(last->last_rw) = bi_rw;
}
rcu_read_lock();
list_for_each_entry_rcu(s, &stats->list, list_entry)
__dm_stat_bio(s, bi_rw, bi_sector, end_sector, end, duration, stats_aux);
rcu_read_unlock();
}
static void __dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *shared,
struct dm_stat *s, size_t x)
{
int cpu;
struct dm_stat_percpu *p;
local_irq_disable();
p = &s->stat_percpu[smp_processor_id()][x];
dm_stat_round(shared, p);
local_irq_enable();
memset(&shared->tmp, 0, sizeof(shared->tmp));
for_each_possible_cpu(cpu) {
p = &s->stat_percpu[cpu][x];
shared->tmp.sectors[READ] += ACCESS_ONCE(p->sectors[READ]);
shared->tmp.sectors[WRITE] += ACCESS_ONCE(p->sectors[WRITE]);
shared->tmp.ios[READ] += ACCESS_ONCE(p->ios[READ]);
shared->tmp.ios[WRITE] += ACCESS_ONCE(p->ios[WRITE]);
shared->tmp.merges[READ] += ACCESS_ONCE(p->merges[READ]);
shared->tmp.merges[WRITE] += ACCESS_ONCE(p->merges[WRITE]);
shared->tmp.ticks[READ] += ACCESS_ONCE(p->ticks[READ]);
shared->tmp.ticks[WRITE] += ACCESS_ONCE(p->ticks[WRITE]);
shared->tmp.io_ticks[READ] += ACCESS_ONCE(p->io_ticks[READ]);
shared->tmp.io_ticks[WRITE] += ACCESS_ONCE(p->io_ticks[WRITE]);
shared->tmp.io_ticks_total += ACCESS_ONCE(p->io_ticks_total);
shared->tmp.time_in_queue += ACCESS_ONCE(p->time_in_queue);
}
}
static void __dm_stat_clear(struct dm_stat *s, size_t idx_start, size_t idx_end,
bool init_tmp_percpu_totals)
{
size_t x;
struct dm_stat_shared *shared;
struct dm_stat_percpu *p;
for (x = idx_start; x < idx_end; x++) {
shared = &s->stat_shared[x];
if (init_tmp_percpu_totals)
__dm_stat_init_temporary_percpu_totals(shared, s, x);
local_irq_disable();
p = &s->stat_percpu[smp_processor_id()][x];
p->sectors[READ] -= shared->tmp.sectors[READ];
p->sectors[WRITE] -= shared->tmp.sectors[WRITE];
p->ios[READ] -= shared->tmp.ios[READ];
p->ios[WRITE] -= shared->tmp.ios[WRITE];
p->merges[READ] -= shared->tmp.merges[READ];
p->merges[WRITE] -= shared->tmp.merges[WRITE];
p->ticks[READ] -= shared->tmp.ticks[READ];
p->ticks[WRITE] -= shared->tmp.ticks[WRITE];
p->io_ticks[READ] -= shared->tmp.io_ticks[READ];
p->io_ticks[WRITE] -= shared->tmp.io_ticks[WRITE];
p->io_ticks_total -= shared->tmp.io_ticks_total;
p->time_in_queue -= shared->tmp.time_in_queue;
local_irq_enable();
}
}
static int dm_stats_clear(struct dm_stats *stats, int id)
{
struct dm_stat *s;
mutex_lock(&stats->mutex);
s = __dm_stats_find(stats, id);
if (!s) {
mutex_unlock(&stats->mutex);
return -ENOENT;
}
__dm_stat_clear(s, 0, s->n_entries, true);
mutex_unlock(&stats->mutex);
return 1;
}
/*
* This is like jiffies_to_msec, but works for 64-bit values.
*/
static unsigned long long dm_jiffies_to_msec64(unsigned long long j)
{
unsigned long long result = 0;
unsigned mult;
if (j)
result = jiffies_to_msecs(j & 0x3fffff);
if (j >= 1 << 22) {
mult = jiffies_to_msecs(1 << 22);
result += (unsigned long long)mult * (unsigned long long)jiffies_to_msecs((j >> 22) & 0x3fffff);
}
if (j >= 1ULL << 44)
result += (unsigned long long)mult * (unsigned long long)mult * (unsigned long long)jiffies_to_msecs(j >> 44);
return result;
}
static int dm_stats_print(struct dm_stats *stats, int id,
size_t idx_start, size_t idx_len,
bool clear, char *result, unsigned maxlen)
{
unsigned sz = 0;
struct dm_stat *s;
size_t x;
sector_t start, end, step;
size_t idx_end;
struct dm_stat_shared *shared;
/*
* Output format:
* <start_sector>+<length> counters
*/
mutex_lock(&stats->mutex);
s = __dm_stats_find(stats, id);
if (!s) {
mutex_unlock(&stats->mutex);
return -ENOENT;
}
idx_end = idx_start + idx_len;
if (idx_end < idx_start ||
idx_end > s->n_entries)
idx_end = s->n_entries;
if (idx_start > idx_end)
idx_start = idx_end;
step = s->step;
start = s->start + (step * idx_start);
for (x = idx_start; x < idx_end; x++, start = end) {
shared = &s->stat_shared[x];
end = start + step;
if (unlikely(end > s->end))
end = s->end;
__dm_stat_init_temporary_percpu_totals(shared, s, x);
DMEMIT("%llu+%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu\n",
(unsigned long long)start,
(unsigned long long)step,
shared->tmp.ios[READ],
shared->tmp.merges[READ],
shared->tmp.sectors[READ],
dm_jiffies_to_msec64(shared->tmp.ticks[READ]),
shared->tmp.ios[WRITE],
shared->tmp.merges[WRITE],
shared->tmp.sectors[WRITE],
dm_jiffies_to_msec64(shared->tmp.ticks[WRITE]),
dm_stat_in_flight(shared),
dm_jiffies_to_msec64(shared->tmp.io_ticks_total),
dm_jiffies_to_msec64(shared->tmp.time_in_queue),
dm_jiffies_to_msec64(shared->tmp.io_ticks[READ]),
dm_jiffies_to_msec64(shared->tmp.io_ticks[WRITE]));
if (unlikely(sz + 1 >= maxlen))
goto buffer_overflow;
}
if (clear)
__dm_stat_clear(s, idx_start, idx_end, false);
buffer_overflow:
mutex_unlock(&stats->mutex);
return 1;
}
static int dm_stats_set_aux(struct dm_stats *stats, int id, const char *aux_data)
{
struct dm_stat *s;
const char *new_aux_data;
mutex_lock(&stats->mutex);
s = __dm_stats_find(stats, id);
if (!s) {
mutex_unlock(&stats->mutex);
return -ENOENT;
}
new_aux_data = kstrdup(aux_data, GFP_KERNEL);
if (!new_aux_data) {
mutex_unlock(&stats->mutex);
return -ENOMEM;
}
kfree(s->aux_data);
s->aux_data = new_aux_data;
mutex_unlock(&stats->mutex);
return 0;
}
static int message_stats_create(struct mapped_device *md,
unsigned argc, char **argv,
char *result, unsigned maxlen)
{
int id;
char dummy;
unsigned long long start, end, len, step;
unsigned divisor;
const char *program_id, *aux_data;
/*
* Input format:
* <range> <step> [<program_id> [<aux_data>]]
*/
if (argc < 3 || argc > 5)
return -EINVAL;
if (!strcmp(argv[1], "-")) {
start = 0;
len = dm_get_size(md);
if (!len)
len = 1;
} else if (sscanf(argv[1], "%llu+%llu%c", &start, &len, &dummy) != 2 ||
start != (sector_t)start || len != (sector_t)len)
return -EINVAL;
end = start + len;
if (start >= end)
return -EINVAL;
if (sscanf(argv[2], "/%u%c", &divisor, &dummy) == 1) {
step = end - start;
if (do_div(step, divisor))
step++;
if (!step)
step = 1;
} else if (sscanf(argv[2], "%llu%c", &step, &dummy) != 1 ||
step != (sector_t)step || !step)
return -EINVAL;
program_id = "-";
aux_data = "-";
if (argc > 3)
program_id = argv[3];
if (argc > 4)
aux_data = argv[4];
/*
* If a buffer overflow happens after we created the region,
* it's too late (the userspace would retry with a larger
* buffer, but the region id that caused the overflow is already
* leaked). So we must detect buffer overflow in advance.
*/
snprintf(result, maxlen, "%d", INT_MAX);
if (dm_message_test_buffer_overflow(result, maxlen))
return 1;
id = dm_stats_create(dm_get_stats(md), start, end, step, program_id, aux_data,
dm_internal_suspend, dm_internal_resume, md);
if (id < 0)
return id;
snprintf(result, maxlen, "%d", id);
return 1;
}
static int message_stats_delete(struct mapped_device *md,
unsigned argc, char **argv)
{
int id;
char dummy;
if (argc != 2)
return -EINVAL;
if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
return -EINVAL;
return dm_stats_delete(dm_get_stats(md), id);
}
static int message_stats_clear(struct mapped_device *md,
unsigned argc, char **argv)
{
int id;
char dummy;
if (argc != 2)
return -EINVAL;
if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
return -EINVAL;
return dm_stats_clear(dm_get_stats(md), id);
}
static int message_stats_list(struct mapped_device *md,
unsigned argc, char **argv,
char *result, unsigned maxlen)
{
int r;
const char *program = NULL;
if (argc < 1 || argc > 2)
return -EINVAL;
if (argc > 1) {
program = kstrdup(argv[1], GFP_KERNEL);
if (!program)
return -ENOMEM;
}
r = dm_stats_list(dm_get_stats(md), program, result, maxlen);
kfree(program);
return r;
}
static int message_stats_print(struct mapped_device *md,
unsigned argc, char **argv, bool clear,
char *result, unsigned maxlen)
{
int id;
char dummy;
unsigned long idx_start = 0, idx_len = ULONG_MAX;
if (argc != 2 && argc != 4)
return -EINVAL;
if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
return -EINVAL;
if (argc > 3) {
if (strcmp(argv[2], "-") &&
sscanf(argv[2], "%lu%c", &idx_start, &dummy) != 1)
return -EINVAL;
if (strcmp(argv[3], "-") &&
sscanf(argv[3], "%lu%c", &idx_len, &dummy) != 1)
return -EINVAL;
}
return dm_stats_print(dm_get_stats(md), id, idx_start, idx_len, clear,
result, maxlen);
}
static int message_stats_set_aux(struct mapped_device *md,
unsigned argc, char **argv)
{
int id;
char dummy;
if (argc != 3)
return -EINVAL;
if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
return -EINVAL;
return dm_stats_set_aux(dm_get_stats(md), id, argv[2]);
}
int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
char *result, unsigned maxlen)
{
int r;
if (dm_request_based(md)) {
DMWARN("Statistics are only supported for bio-based devices");
return -EOPNOTSUPP;
}
/* All messages here must start with '@' */
if (!strcasecmp(argv[0], "@stats_create"))
r = message_stats_create(md, argc, argv, result, maxlen);
else if (!strcasecmp(argv[0], "@stats_delete"))
r = message_stats_delete(md, argc, argv);
else if (!strcasecmp(argv[0], "@stats_clear"))
r = message_stats_clear(md, argc, argv);
else if (!strcasecmp(argv[0], "@stats_list"))
r = message_stats_list(md, argc, argv, result, maxlen);
else if (!strcasecmp(argv[0], "@stats_print"))
r = message_stats_print(md, argc, argv, false, result, maxlen);
else if (!strcasecmp(argv[0], "@stats_print_clear"))
r = message_stats_print(md, argc, argv, true, result, maxlen);
else if (!strcasecmp(argv[0], "@stats_set_aux"))
r = message_stats_set_aux(md, argc, argv);
else
return 2; /* this wasn't a stats message */
if (r == -EINVAL)
DMWARN("Invalid parameters for message %s", argv[0]);
return r;
}
int __init dm_statistics_init(void)
{
dm_stat_need_rcu_barrier = 0;
return 0;
}
void dm_statistics_exit(void)
{
if (dm_stat_need_rcu_barrier)
rcu_barrier();
if (WARN_ON(shared_memory_amount))
DMCRIT("shared_memory_amount leaked: %lu", shared_memory_amount);
}
module_param_named(stats_current_allocated_bytes, shared_memory_amount, ulong, S_IRUGO);
MODULE_PARM_DESC(stats_current_allocated_bytes, "Memory currently used by statistics");

40
drivers/md/dm-stats.h Normal file
View file

@ -0,0 +1,40 @@
#ifndef DM_STATS_H
#define DM_STATS_H
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/list.h>
int dm_statistics_init(void);
void dm_statistics_exit(void);
struct dm_stats {
struct mutex mutex;
struct list_head list; /* list of struct dm_stat */
struct dm_stats_last_position __percpu *last;
sector_t last_sector;
unsigned last_rw;
};
struct dm_stats_aux {
bool merged;
};
void dm_stats_init(struct dm_stats *st);
void dm_stats_cleanup(struct dm_stats *st);
struct mapped_device;
int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
char *result, unsigned maxlen);
void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw,
sector_t bi_sector, unsigned bi_sectors, bool end,
unsigned long duration, struct dm_stats_aux *aux);
static inline bool dm_stats_used(struct dm_stats *st)
{
return !list_empty(&st->list);
}
#endif

65
drivers/md/dm.c
View file

@ -60,6 +60,7 @@ struct dm_io {
struct bio *bio;
unsigned long start_time;
spinlock_t endio_lock;
struct dm_stats_aux stats_aux;
};
/*
@ -198,6 +199,8 @@ struct mapped_device {
/* zero-length flush that will be cloned and submitted to targets */
struct bio flush_bio;
struct dm_stats stats;
};
/*
@ -269,6 +272,7 @@ static int (*_inits[])(void) __initdata = {
dm_io_init,
dm_kcopyd_init,
dm_interface_init,
dm_statistics_init,
};
static void (*_exits[])(void) = {
@ -279,6 +283,7 @@ static void (*_exits[])(void) = {
dm_io_exit,
dm_kcopyd_exit,
dm_interface_exit,
dm_statistics_exit,
};
static int __init dm_init(void)
@ -384,6 +389,16 @@ int dm_lock_for_deletion(struct mapped_device *md)
return r;
}
sector_t dm_get_size(struct mapped_device *md)
{
return get_capacity(md->disk);
}
struct dm_stats *dm_get_stats(struct mapped_device *md)
{
return &md->stats;
}
static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
struct mapped_device *md = bdev->bd_disk->private_data;
@ -466,8 +481,9 @@ static int md_in_flight(struct mapped_device *md)
static void start_io_acct(struct dm_io *io)
{
struct mapped_device *md = io->md;
struct bio *bio = io->bio;
int cpu;
int rw = bio_data_dir(io->bio);
int rw = bio_data_dir(bio);
io->start_time = jiffies;
@ -476,6 +492,10 @@ static void start_io_acct(struct dm_io *io)
part_stat_unlock();
atomic_set(&dm_disk(md)->part0.in_flight[rw],
atomic_inc_return(&md->pending[rw]));
if (unlikely(dm_stats_used(&md->stats)))
dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector,
bio_sectors(bio), false, 0, &io->stats_aux);
}
static void end_io_acct(struct dm_io *io)
@ -491,6 +511,10 @@ static void end_io_acct(struct dm_io *io)
part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
part_stat_unlock();
if (unlikely(dm_stats_used(&md->stats)))
dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_sector,
bio_sectors(bio), true, duration, &io->stats_aux);
/*
* After this is decremented the bio must not be touched if it is
* a flush.
@ -1519,7 +1543,7 @@ static void _dm_request(struct request_queue *q, struct bio *bio)
return;
}
static int dm_request_based(struct mapped_device *md)
int dm_request_based(struct mapped_device *md)
{
return blk_queue_stackable(md->queue);
}
@ -1958,6 +1982,8 @@ static struct mapped_device *alloc_dev(int minor)
md->flush_bio.bi_bdev = md->bdev;
md->flush_bio.bi_rw = WRITE_FLUSH;
dm_stats_init(&md->stats);
/* Populate the mapping, nobody knows we exist yet */
spin_lock(&_minor_lock);
old_md = idr_replace(&_minor_idr, md, minor);
@ -2009,6 +2035,7 @@ static void free_dev(struct mapped_device *md)
put_disk(md->disk);
blk_cleanup_queue(md->queue);
dm_stats_cleanup(&md->stats);
module_put(THIS_MODULE);
kfree(md);
}
@ -2150,7 +2177,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
/*
* Wipe any geometry if the size of the table changed.
*/
if (size != get_capacity(md->disk))
if (size != dm_get_size(md))
memset(&md->geometry, 0, sizeof(md->geometry));
__set_size(md, size);
@ -2696,6 +2723,38 @@ int dm_resume(struct mapped_device *md)
return r;
}
/*
* Internal suspend/resume works like userspace-driven suspend. It waits
* until all bios finish and prevents issuing new bios to the target drivers.
* It may be used only from the kernel.
*
* Internal suspend holds md->suspend_lock, which prevents interaction with
* userspace-driven suspend.
*/
void dm_internal_suspend(struct mapped_device *md)
{
mutex_lock(&md->suspend_lock);
if (dm_suspended_md(md))
return;
set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
synchronize_srcu(&md->io_barrier);
flush_workqueue(md->wq);
dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
}
void dm_internal_resume(struct mapped_device *md)
{
if (dm_suspended_md(md))
goto done;
dm_queue_flush(md);
done:
mutex_unlock(&md->suspend_lock);
}
/*-----------------------------------------------------------------
* Event notification.
*---------------------------------------------------------------*/

16
drivers/md/dm.h
View file

@ -16,6 +16,8 @@
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include "dm-stats.h"
/*
* Suspend feature flags
*/
@ -157,10 +159,16 @@ void dm_destroy(struct mapped_device *md);
void dm_destroy_immediate(struct mapped_device *md);
int dm_open_count(struct mapped_device *md);
int dm_lock_for_deletion(struct mapped_device *md);
int dm_request_based(struct mapped_device *md);
sector_t dm_get_size(struct mapped_device *md);
struct dm_stats *dm_get_stats(struct mapped_device *md);
int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
unsigned cookie);
void dm_internal_suspend(struct mapped_device *md);
void dm_internal_resume(struct mapped_device *md);
int dm_io_init(void);
void dm_io_exit(void);
@ -173,4 +181,12 @@ void dm_kcopyd_exit(void);
struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size);
void dm_free_md_mempools(struct dm_md_mempools *pools);
/*
* Helpers that are used by DM core
*/
static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen)
{
return !maxlen || strlen(result) + 1 >= maxlen;
}
#endif

9
include/linux/device-mapper.h
View file

@ -10,6 +10,7 @@
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/math64.h>
#include <linux/ratelimit.h>
struct dm_dev;
@ -550,6 +551,14 @@ extern struct ratelimit_state dm_ratelimit_state;
#define DM_MAPIO_REMAPPED 1
#define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE
#define dm_sector_div64(x, y)( \
{ \
u64 _res; \
(x) = div64_u64_rem(x, y, &_res); \
_res; \
} \
)
/*
* Ceiling(n / sz)
*/

4
include/uapi/linux/dm-ioctl.h
View file

@ -267,9 +267,9 @@ enum {
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
#define DM_VERSION_MINOR 25
#define DM_VERSION_MINOR 26
#define DM_VERSION_PATCHLEVEL 0
#define DM_VERSION_EXTRA "-ioctl (2013-06-26)"
#define DM_VERSION_EXTRA "-ioctl (2013-08-15)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */