lvm2/libdm/libdm-stats.c

/*
 * Copyright (C) 2016 Red Hat, Inc. All rights reserved.
 *
 * _stats_get_extents_for_file() based in part on filefrag_fiemap() from
 * e2fsprogs/misc/filefrag.c. Copyright 2003 by Theodore Ts'o.
 *
 * This file is part of the device-mapper userspace tools.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libdm/misc/dmlib.h"
#include "libdm/misc/kdev_t.h"

#include "math.h" /* log10() */

#include <sys/sysmacros.h>
#include <sys/ioctl.h>
#include <sys/vfs.h> /* fstatfs */

#ifdef __linux__
  #include <linux/fs.h> /* FS_IOC_FIEMAP */
#endif

#ifdef HAVE_LINUX_FIEMAP_H
  #include <linux/fiemap.h> /* fiemap */
#endif

#ifdef HAVE_LINUX_MAGIC_H
  #include <linux/magic.h> /* BTRFS_SUPER_MAGIC */
#endif

#define DM_STATS_REGION_NOT_PRESENT UINT64_MAX
#define DM_STATS_GROUP_NOT_PRESENT DM_STATS_GROUP_NONE

#define NSEC_PER_USEC   1000L
#define NSEC_PER_MSEC   1000000L
#define NSEC_PER_SEC    1000000000L

#define PRECISE_ARG "precise_timestamps"
#define HISTOGRAM_ARG "histogram:"

#define STATS_ROW_BUF_LEN 4096
#define STATS_MSG_BUF_LEN 1024
#define STATS_FIE_BUF_LEN 2048

#define SECTOR_SHIFT 9L

/* Histogram bin */
struct dm_histogram_bin {
	uint64_t upper; /* Upper bound on this bin. */
	uint64_t count; /* Count value for this bin. */
};

struct dm_histogram {
	/* The stats handle this histogram belongs to. */
	const struct dm_stats *dms;
	/* The region this histogram belongs to. */
	const struct dm_stats_region *region;
	uint64_t sum; /* Sum of histogram bin counts. */
	int nr_bins; /* Number of histogram bins assigned. */
	struct dm_histogram_bin bins[];
};

/*
 * See Documentation/device-mapper/statistics.txt for full descriptions
 * of the device-mapper statistics counter fields.
 */
struct dm_stats_counters {
	uint64_t reads;		    /* Num reads completed */
	uint64_t reads_merged;	    /* Num reads merged */
	uint64_t read_sectors;	    /* Num sectors read */
	uint64_t read_nsecs;	    /* Num milliseconds spent reading */
	uint64_t writes;	    /* Num writes completed */
	uint64_t writes_merged;	    /* Num writes merged */
	uint64_t write_sectors;	    /* Num sectors written */
	uint64_t write_nsecs;	    /* Num milliseconds spent writing */
	uint64_t io_in_progress;    /* Num I/Os currently in progress */
	uint64_t io_nsecs;	    /* Num milliseconds spent doing I/Os */
	uint64_t weighted_io_nsecs; /* Weighted num milliseconds doing I/Os */
	uint64_t total_read_nsecs;  /* Total time spent reading in milliseconds */
	uint64_t total_write_nsecs; /* Total time spent writing in milliseconds */
	struct dm_histogram *histogram; /* Histogram. */
};

struct dm_stats_region {
	uint64_t region_id; /* as returned by @stats_list */
	uint64_t group_id;
	uint64_t start;
	uint64_t len;
	uint64_t step;
	char *program_id;
	char *aux_data;
	uint64_t timescale; /* precise_timestamps is per-region */
	struct dm_histogram *bounds; /* histogram configuration */
	struct dm_histogram *histogram; /* aggregate cache */
	struct dm_stats_counters *counters;
};

struct dm_stats_group {
	uint64_t group_id;
	const char *alias;
	dm_bitset_t regions;
	struct dm_histogram *histogram;
};

struct dm_stats {
	/* device binding */
	int bind_major;  /* device major that this dm_stats object is bound to */
	int bind_minor;  /* device minor that this dm_stats object is bound to */
	char *bind_name; /* device-mapper device name */
	char *bind_uuid; /* device-mapper UUID */
	char *program_id; /* default program_id for this handle */
	const char *name; /* cached device_name used for reporting */
	struct dm_pool *mem; /* memory pool for region and counter tables */
	struct dm_pool *hist_mem; /* separate pool for histogram tables */
	struct dm_pool *group_mem; /* separate pool for group tables */
	uint64_t nr_regions; /* total number of present regions */
	uint64_t max_region; /* size of the regions table */
	uint64_t interval_ns;  /* sampling interval in nanoseconds */
	uint64_t timescale; /* default sample value multiplier */
	int precise; /* use precise_timestamps when creating regions */
	struct dm_stats_region *regions;
	struct dm_stats_group *groups;
	/* statistics cursor */
	uint64_t walk_flags; /* walk control flags */
	uint64_t cur_flags;
	uint64_t cur_group;
	uint64_t cur_region;
	uint64_t cur_area;
};

static char *_stats_escape_aux_data(const char *aux_data)
{
	size_t aux_data_len = strlen(aux_data);
	char *escaped = dm_malloc((3 * aux_data_len + 1) * sizeof(char));
	size_t index = 0, i;

	if (!escaped) {
		log_error("Could not allocate memory for escaped "
			  "aux_data string.");
		return NULL;
	}

	for (i = 0; i < aux_data_len; i++) {
		if (aux_data[i] == ' ') {
			escaped[index++] = '\\';
			escaped[index++] = ' ';
		} else if (aux_data[i] == '\\') {
			escaped[index++] = '\\';
			escaped[index++] = '\\';
		} else if (aux_data[i] == '\t') {
			escaped[index++] = '\\';
			escaped[index++] = '\t';
		} else {
			escaped[index++] = aux_data[i];
		}
	}
	escaped[index] = '\0';
	return escaped;
}

#define PROC_SELF_COMM "/proc/self/comm"
static char *_program_id_from_proc(void)
{
	FILE *comm = NULL;
	char buf[STATS_ROW_BUF_LEN];

	if (!(comm = fopen(PROC_SELF_COMM, "r")))
		return_NULL;

	if (!fgets(buf, sizeof(buf), comm)) {
		log_error("Could not read from %s", PROC_SELF_COMM);
		if (fclose(comm))
			stack;
		return NULL;
	}

	if (fclose(comm))
		stack;

	return dm_strdup(buf);
}

static uint64_t _nr_areas(uint64_t len, uint64_t step)
{
	/* Default is one area. */
	if (!len || !step)
		return 1;
	/*
	 * drivers/md/dm-stats.c::message_stats_create()
	 * A region may be sub-divided into areas with their own counters.
	 * Any partial area at the end of the region is treated as an
	 * additional complete area.
	 */
	return (len + step - 1) / step;
}

static uint64_t _nr_areas_region(struct dm_stats_region *region)
{
	return _nr_areas(region->len, region->step);
}

struct dm_stats *dm_stats_create(const char *program_id)
{
	size_t hist_hint = sizeof(struct dm_histogram_bin);
	size_t group_hint = sizeof(struct dm_stats_group);
	struct dm_stats *dms = NULL;

	if (!(dms = dm_zalloc(sizeof(*dms))))
		return_NULL;

	/* FIXME: better hint. */
	if (!(dms->mem = dm_pool_create("stats_pool", 4096))) {
		dm_free(dms);
		return_NULL;
	}

	if (!(dms->hist_mem = dm_pool_create("histogram_pool", hist_hint)))
		goto_bad;

	if (!(dms->group_mem = dm_pool_create("group_pool", group_hint)))
		goto_bad;

	if (!program_id || !strlen(program_id))
		dms->program_id = _program_id_from_proc();
	else
		dms->program_id = dm_strdup(program_id);

	if (!dms->program_id) {
		log_error("Could not allocate memory for program_id");
		goto bad;
	}

	dms->bind_major = -1;
	dms->bind_minor = -1;
	dms->bind_name = NULL;
	dms->bind_uuid = NULL;

	dms->name = NULL;

	/* by default all regions use msec precision */
	dms->timescale = NSEC_PER_MSEC;
	dms->precise = 0;

	dms->nr_regions = DM_STATS_REGION_NOT_PRESENT;
	dms->max_region = DM_STATS_REGION_NOT_PRESENT;
	dms->regions = NULL;

	/* maintain compatibility with earlier walk version */
	dms->walk_flags = dms->cur_flags = DM_STATS_WALK_DEFAULT;

	return dms;

bad:
	dm_pool_destroy(dms->mem);
	if (dms->hist_mem)
		dm_pool_destroy(dms->hist_mem);
	if (dms->group_mem)
		dm_pool_destroy(dms->group_mem);
	dm_free(dms);
	return NULL;
}

/*
 * Test whether the stats region pointed to by region is present.
 */
static int _stats_region_present(const struct dm_stats_region *region)
{
	return !(region->region_id == DM_STATS_REGION_NOT_PRESENT);
}

/*
 * Test whether the stats group pointed to by group is present.
 */
static int _stats_group_present(const struct dm_stats_group *group)
{
	return !(group->group_id == DM_STATS_GROUP_NOT_PRESENT);
}

/*
 * Test whether a stats group id is present.
 */
static int _stats_group_id_present(const struct dm_stats *dms, uint64_t id)
{
	struct dm_stats_group *group = NULL;

	if (id == DM_STATS_GROUP_NOT_PRESENT)
		return 0;

	if (!dms)
		return_0;

	if (!dms->regions)
		return 0;

	if (id > dms->max_region)
		return 0;

	group = &dms->groups[id];

	return _stats_group_present(group);
}

/*
 * Test whether the given region_id is a member of any group.
 */
static uint64_t _stats_region_is_grouped(const struct dm_stats* dms,
					 uint64_t region_id)
{
	uint64_t group_id;

	if (region_id == DM_STATS_GROUP_NOT_PRESENT)
		return 0;

	if (!_stats_region_present(&dms->regions[region_id]))
		return 0;

	group_id = dms->regions[region_id].group_id;

	return group_id != DM_STATS_GROUP_NOT_PRESENT;
}

static void _stats_histograms_destroy(struct dm_pool *mem,
				      struct dm_stats_region *region)
{
	/* Unpopulated handle. */
	if (!region->counters)
		return;

	/*
	 * Free everything in the pool back to the first histogram.
	 */
	if (region->counters[0].histogram)
		dm_pool_free(mem, region->counters[0].histogram);
}

static void _stats_region_destroy(struct dm_stats_region *region)
{
	if (!_stats_region_present(region))
		return;

	region->start = region->len = region->step = 0;
	region->timescale = 0;

	/*
	 * Don't free counters and histogram bounds here: they are
	 * dropped from the pool along with the corresponding
	 * regions table.
	 *
	 * The following objects are all allocated with dm_malloc.
	 */

	region->counters = NULL;
	region->bounds = NULL;

	dm_free(region->program_id);
	region->program_id = NULL;
	dm_free(region->aux_data);
	region->aux_data = NULL;
	region->region_id = DM_STATS_REGION_NOT_PRESENT;
}

static void _stats_regions_destroy(struct dm_stats *dms)
{
	struct dm_pool *mem = dms->mem;
	uint64_t i;

	if (!dms->regions)
		return;

	/* walk backwards to obey pool order */
	for (i = dms->max_region; (i != DM_STATS_REGION_NOT_PRESENT); i--) {
		_stats_histograms_destroy(dms->hist_mem, &dms->regions[i]);
		_stats_region_destroy(&dms->regions[i]);
	}

	dm_pool_free(mem, dms->regions);
	dms->regions = NULL;
}

static void _stats_group_destroy(struct dm_stats_group *group)
{
	if (!_stats_group_present(group))
		return;

	group->histogram = NULL;

	if (group->alias) {
		dm_free((char *) group->alias);
		group->alias = NULL;
	}
	if (group->regions) {
		dm_bitset_destroy(group->regions);
		group->regions = NULL;
	}
	group->group_id = DM_STATS_GROUP_NOT_PRESENT;
}

static void _stats_groups_destroy(struct dm_stats *dms)
{
	uint64_t i;

	if (!dms->groups)
		return;

	for (i = dms->max_region; (i != DM_STATS_REGION_NOT_PRESENT); i--)
		_stats_group_destroy(&dms->groups[i]);
	dm_pool_free(dms->group_mem, dms->groups);
	dms->groups = NULL;
}

static int _set_stats_device(struct dm_stats *dms, struct dm_task *dmt)
{
	if (dms->bind_name)
		return dm_task_set_name(dmt, dms->bind_name);
	if (dms->bind_uuid)
		return dm_task_set_uuid(dmt, dms->bind_uuid);
	if (dms->bind_major > 0)
		return dm_task_set_major(dmt, dms->bind_major)
			&& dm_task_set_minor(dmt, dms->bind_minor);
	return_0;
}

static int _stats_bound(const struct dm_stats *dms)
{
	if (dms->bind_major > 0 || dms->bind_name || dms->bind_uuid)
		return 1;
	/* %p format specifier expects a void pointer. */
	log_error("Stats handle at %p is not bound.", (const void *)dms);
	return 0;
}

static void _stats_clear_binding(struct dm_stats *dms)
{
	if (dms->bind_name)
		dm_pool_free(dms->mem, dms->bind_name);
	if (dms->bind_uuid)
		dm_pool_free(dms->mem, dms->bind_uuid);
	dm_free((char *) dms->name);

	dms->bind_name = dms->bind_uuid = NULL;
	dms->bind_major = dms->bind_minor = -1;
	dms->name = NULL;
}

int dm_stats_bind_devno(struct dm_stats *dms, int major, int minor)
{
	_stats_clear_binding(dms);
	_stats_regions_destroy(dms);
	_stats_groups_destroy(dms);

	dms->bind_major = major;
	dms->bind_minor = minor;

	return 1;
}

int dm_stats_bind_name(struct dm_stats *dms, const char *name)
{
	_stats_clear_binding(dms);
	_stats_regions_destroy(dms);
	_stats_groups_destroy(dms);

	if (!(dms->bind_name = dm_pool_strdup(dms->mem, name)))
		return_0;

	return 1;
}

int dm_stats_bind_uuid(struct dm_stats *dms, const char *uuid)
{
	_stats_clear_binding(dms);
	_stats_regions_destroy(dms);
	_stats_groups_destroy(dms);

	if (!(dms->bind_uuid = dm_pool_strdup(dms->mem, uuid)))
		return_0;

	return 1;
}

int dm_stats_bind_from_fd(struct dm_stats *dms, int fd)
{
        int major, minor;
        struct stat buf;

        if (fstat(fd, &buf)) {
                log_error("fstat failed for fd %d.", fd);
                return 0;
        }

        major = (int) MAJOR(buf.st_dev);
        minor = (int) MINOR(buf.st_dev);

        if (!dm_stats_bind_devno(dms, major, minor))
                return_0;
        return 1;
}

static int _stats_check_precise_timestamps(const struct dm_stats *dms)
{
	/* Already checked? */
	if (dms && dms->precise)
		return 1;

	return dm_message_supports_precise_timestamps();
}

int dm_stats_driver_supports_precise(void)
{
	return _stats_check_precise_timestamps(NULL);
}

int dm_stats_driver_supports_histogram(void)
{
	return _stats_check_precise_timestamps(NULL);
}

static int _fill_hist_arg(char *hist_arg, size_t hist_len, uint64_t scale,
			  struct dm_histogram *bounds)
{
	int i, l, len = 0, nr_bins;
	char *arg = hist_arg;
	uint64_t value;

	nr_bins = bounds->nr_bins;

	for (i = 0; i < nr_bins; i++) {
		value = bounds->bins[i].upper / scale;
		if ((l = dm_snprintf(arg, hist_len - len, FMTu64"%s", value,
				     (i == (nr_bins - 1)) ? "" : ",")) < 0)
			return_0;
		len += l;
		arg += l;
	}
	return 1;
}

static void *_get_hist_arg(struct dm_histogram *bounds, uint64_t scale,
			   size_t *len)
{
	struct dm_histogram_bin *entry, *bins;
	size_t hist_len = 1; /* terminating '\0' */
	double value;

	entry = bins = bounds->bins;

	entry += bounds->nr_bins - 1;
	while(entry >= bins) {
		value = (double) (entry--)->upper;
		/* Use lround to avoid size_t -> double cast warning. */
		hist_len += 1 + (size_t) lround(log10(value / scale));
		if (entry != bins)
			hist_len++; /* ',' */
	}

	*len = hist_len;

	return dm_zalloc(hist_len);
}

static char *_build_histogram_arg(struct dm_histogram *bounds, int *precise)
{
	struct dm_histogram_bin *entry, *bins;
	size_t hist_len;
	char *hist_arg;
	uint64_t scale;

	entry = bins = bounds->bins;

	/* Empty histogram is invalid. */
	if (!bounds->nr_bins) {
		log_error("Cannot format empty histogram description.");
		return NULL;
	}

	/* Validate entries and set *precise if precision < 1ms. */
	entry += bounds->nr_bins - 1;
	while (entry >= bins) {
		if (entry != bins) {
			if (entry->upper < (entry - 1)->upper) {
				log_error("Histogram boundaries must be in "
					  "order of increasing magnitude.");
				return 0;
			}
		}

		/*
		 * Only enable precise_timestamps automatically if any
		 * value in the histogram bounds uses precision < 1ms.
		 */
		if (((entry--)->upper % NSEC_PER_MSEC) && !*precise)
			*precise = 1;
	}

	scale = (*precise) ? 1 : NSEC_PER_MSEC;

	/* Calculate hist_len and allocate a character buffer. */
	if (!(hist_arg = _get_hist_arg(bounds, scale, &hist_len))) {
		log_error("Could not allocate memory for histogram argument.");
		return 0;
	}

	/* Fill hist_arg with boundary strings. */
	if (!_fill_hist_arg(hist_arg, hist_len, scale, bounds))
		goto_bad;

	return hist_arg;

bad:
	log_error("Could not build histogram arguments.");
	dm_free(hist_arg);