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Add callbacks for displaying KSTAT_TYPE_RAW kstats
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The current implementation for displaying kstats of type KSTAT_TYPE_RAW
is rather crude. This patch attempts to enhance this handling by
allowing a kstat user to register formatting callbacks which can
optionally be used.

The callbacks allow the user to implement functions for interpreting
their data and transposing it into a character buffer. This buffer,
containing a string representation of the raw data, is then be displayed
through the current /proc textual interface.

Additionally the kstats are made writable because it's now possible
to provide a useful handler via the existing ks_update() interface.

Signed-off-by: Prakash Surya <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #296
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@behlendorf
Prakash Surya authored and behlendorf committed Oct 16, 2013
1 parent 4768c0d commit 56d40a6
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Showing 2 changed files with 123 additions and 16 deletions.
20 changes: 18 additions & 2 deletions include/sys/kstat.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@
#include <sys/mutex.h>

#define KSTAT_STRLEN 31
#define KSTAT_RAW_MAX (128*1024)

/* For reference valid classes are:
* disk, tape, net, controller, vm, kvm, hat, streams, kstat, misc
Expand Down Expand Up @@ -79,6 +80,7 @@
#define KSTAT_WRITE 1

struct kstat_s;
typedef struct kstat_s kstat_t;

typedef int kid_t; /* unique kstat id */
typedef int kstat_update_t(struct kstat_s *, int); /* dynamic update cb */
Expand All @@ -90,7 +92,13 @@ typedef struct kstat_module {
struct proc_dir_entry *ksm_proc; /* proc entry */
} kstat_module_t;

typedef struct kstat_s {
typedef struct kstat_raw_ops {
int (*headers)(char *buf, size_t size);
int (*data)(char *buf, size_t size, void *data);
void *(*addr)(kstat_t *ksp, loff_t index);
} kstat_raw_ops_t;

struct kstat_s {
int ks_magic; /* magic value */
kid_t ks_kid; /* unique kstat ID */
hrtime_t ks_crtime; /* creation time */
Expand All @@ -110,7 +118,10 @@ typedef struct kstat_s {
kmutex_t ks_lock; /* kstat data lock */
struct list_head ks_list; /* kstat linkage */
kstat_module_t *ks_owner; /* kstat module linkage */
} kstat_t;
kstat_raw_ops_t ks_raw_ops; /* ops table for raw type */
char *ks_raw_buf; /* buf used for raw ops */
size_t ks_raw_bufsize; /* size of raw ops buffer */
};

typedef struct kstat_named_s {
char name[KSTAT_STRLEN]; /* name of counter */
Expand Down Expand Up @@ -188,13 +199,18 @@ typedef struct kstat_txg {
int spl_kstat_init(void);
void spl_kstat_fini(void);

extern void __kstat_set_raw_ops(kstat_t *ksp,
int (*headers)(char *buf, size_t size),
int (*data)(char *buf, size_t size, void *data),
void* (*addr)(kstat_t *ksp, loff_t index));
extern kstat_t *__kstat_create(const char *ks_module, int ks_instance,
const char *ks_name, const char *ks_class,
uchar_t ks_type, uint_t ks_ndata,
uchar_t ks_flags);
extern void __kstat_install(kstat_t *ksp);
extern void __kstat_delete(kstat_t *ksp);

#define kstat_set_raw_ops(k,h,d,a) __kstat_set_raw_ops(k,h,d,a)
#define kstat_create(m,i,n,c,t,s,f) __kstat_create(m,i,n,c,t,s,f)
#define kstat_install(k) __kstat_install(k)
#define kstat_delete(k) __kstat_delete(k)
Expand Down
119 changes: 105 additions & 14 deletions module/spl/spl-kstat.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,10 +41,25 @@ static kmutex_t kstat_module_lock;
static struct list_head kstat_module_list;
static kid_t kstat_id;

static void
static int
kstat_resize_raw(kstat_t *ksp)
{
if (ksp->ks_raw_bufsize == KSTAT_RAW_MAX)
return ENOMEM;

vmem_free(ksp->ks_raw_buf, ksp->ks_raw_bufsize);
ksp->ks_raw_bufsize = MIN(ksp->ks_raw_bufsize * 2, KSTAT_RAW_MAX);
ksp->ks_raw_buf = vmem_alloc(ksp->ks_raw_bufsize, KM_SLEEP);

return 0;
}

static int
kstat_seq_show_headers(struct seq_file *f)
{
kstat_t *ksp = (kstat_t *)f->private;
int rc = 0;

ASSERT(ksp->ks_magic == KS_MAGIC);

seq_printf(f, "%d %d 0x%02x %d %d %lld %lld\n",
Expand All @@ -54,7 +69,17 @@ kstat_seq_show_headers(struct seq_file *f)

switch (ksp->ks_type) {
case KSTAT_TYPE_RAW:
seq_printf(f, "raw data");
restart:
if (ksp->ks_raw_ops.headers) {
rc = ksp->ks_raw_ops.headers(
ksp->ks_raw_buf, ksp->ks_raw_bufsize);
if (rc == ENOMEM && !kstat_resize_raw(ksp))
goto restart;
if (!rc)
seq_puts(f, ksp->ks_raw_buf);
} else {
seq_printf(f, "raw data\n");
}
break;
case KSTAT_TYPE_NAMED:
seq_printf(f, "%-31s %-4s %s\n",
Expand Down Expand Up @@ -92,6 +117,8 @@ kstat_seq_show_headers(struct seq_file *f)
default:
PANIC("Undefined kstat type %d\n", ksp->ks_type);
}

return -rc;
}

static int
Expand Down Expand Up @@ -232,9 +259,19 @@ kstat_seq_show(struct seq_file *f, void *p)

switch (ksp->ks_type) {
case KSTAT_TYPE_RAW:
ASSERT(ksp->ks_ndata == 1);
rc = kstat_seq_show_raw(f, ksp->ks_data,
ksp->ks_data_size);
restart:
if (ksp->ks_raw_ops.data) {
rc = ksp->ks_raw_ops.data(
ksp->ks_raw_buf, ksp->ks_raw_bufsize, p);
if (rc == ENOMEM && !kstat_resize_raw(ksp))
goto restart;
if (!rc)
seq_puts(f, ksp->ks_raw_buf);
} else {
ASSERT(ksp->ks_ndata == 1);
rc = kstat_seq_show_raw(f, ksp->ks_data,
ksp->ks_data_size);
}
break;
case KSTAT_TYPE_NAMED:
rc = kstat_seq_show_named(f, (kstat_named_t *)p);
Expand All @@ -255,13 +292,17 @@ kstat_seq_show(struct seq_file *f, void *p)
PANIC("Undefined kstat type %d\n", ksp->ks_type);
}

return rc;
return -rc;
}

int
kstat_default_update(kstat_t *ksp, int rw)
{
ASSERT(ksp != NULL);

if (rw == KSTAT_WRITE)
return (EACCES);

return 0;
}

Expand All @@ -273,7 +314,10 @@ kstat_seq_data_addr(kstat_t *ksp, loff_t n)

switch (ksp->ks_type) {
case KSTAT_TYPE_RAW:
rc = ksp->ks_data;
if (ksp->ks_raw_ops.addr)
rc = ksp->ks_raw_ops.addr(ksp, n);
else
rc = ksp->ks_data;
break;
case KSTAT_TYPE_NAMED:
rc = ksp->ks_data + n * sizeof(kstat_named_t);
Expand Down Expand Up @@ -307,13 +351,18 @@ kstat_seq_start(struct seq_file *f, loff_t *pos)

mutex_enter(&ksp->ks_lock);

if (ksp->ks_type == KSTAT_TYPE_RAW) {
ksp->ks_raw_bufsize = PAGE_SIZE;
ksp->ks_raw_buf = vmem_alloc(ksp->ks_raw_bufsize, KM_SLEEP);
}

/* Dynamically update kstat, on error existing kstats are used */
(void) ksp->ks_update(ksp, KSTAT_READ);

ksp->ks_snaptime = gethrtime();

if (!n)
kstat_seq_show_headers(f);
if (!n && kstat_seq_show_headers(f))
SRETURN(NULL);

if (n >= ksp->ks_ndata)
SRETURN(NULL);
Expand Down Expand Up @@ -341,6 +390,9 @@ kstat_seq_stop(struct seq_file *f, void *v)
kstat_t *ksp = (kstat_t *)f->private;
ASSERT(ksp->ks_magic == KS_MAGIC);

if (ksp->ks_type == KSTAT_TYPE_RAW)
vmem_free(ksp->ks_raw_buf, ksp->ks_raw_bufsize);

mutex_exit(&ksp->ks_lock);
}

Expand Down Expand Up @@ -408,13 +460,47 @@ proc_kstat_open(struct inode *inode, struct file *filp)
return rc;
}

static ssize_t
proc_kstat_write(struct file *filp, const char __user *buf,
size_t len, loff_t *ppos)
{
struct seq_file *f = filp->private_data;
kstat_t *ksp = f->private;
int rc;

ASSERT(ksp->ks_magic == KS_MAGIC);

mutex_enter(ksp->ks_lock);
rc = ksp->ks_update(ksp, KSTAT_WRITE);
mutex_exit(ksp->ks_lock);

if (rc)
return (-rc);

*ppos += len;
return (len);
}

static struct file_operations proc_kstat_operations = {
.open = proc_kstat_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
.open = proc_kstat_open,
.write = proc_kstat_write,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};

void
__kstat_set_raw_ops(kstat_t *ksp,
int (*headers)(char *buf, size_t size),
int (*data)(char *buf, size_t size, void *data),
void *(*addr)(kstat_t *ksp, loff_t index))
{
ksp->ks_raw_ops.headers = headers;
ksp->ks_raw_ops.data = data;
ksp->ks_raw_ops.addr = addr;
}
EXPORT_SYMBOL(__kstat_set_raw_ops);

kstat_t *
__kstat_create(const char *ks_module, int ks_instance, const char *ks_name,
const char *ks_class, uchar_t ks_type, uint_t ks_ndata,
Expand Down Expand Up @@ -453,6 +539,11 @@ __kstat_create(const char *ks_module, int ks_instance, const char *ks_name,
ksp->ks_flags = ks_flags;
ksp->ks_update = kstat_default_update;
ksp->ks_private = NULL;
ksp->ks_raw_ops.headers = NULL;
ksp->ks_raw_ops.data = NULL;
ksp->ks_raw_ops.addr = NULL;
ksp->ks_raw_buf = NULL;
ksp->ks_raw_bufsize = 0;

switch (ksp->ks_type) {
case KSTAT_TYPE_RAW:
Expand Down Expand Up @@ -526,7 +617,7 @@ __kstat_install(kstat_t *ksp)

mutex_enter(&ksp->ks_lock);
ksp->ks_owner = module;
ksp->ks_proc = proc_create_data(ksp->ks_name, 0444,
ksp->ks_proc = proc_create_data(ksp->ks_name, 0644,
module->ksm_proc, &proc_kstat_operations, (void *)ksp);
if (ksp->ks_proc == NULL) {
list_del_init(&ksp->ks_list);
Expand Down

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