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linux/kstat: allow multi-level module names

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Module names are mapped directly to directory names in procfs, but
nothing is done to create the intermediate directories, or remove them.
This makes it impossible to sensibly present kstats about sub-objects.

This commit loops through '/'-separated names in the full module name,
creates a separate module for each, and hooks them up with a parent
pointer and child counter, and then unrolls this on the other side when
deleting a module.

Sponsored-by: Klara, Inc.
Sponsored-by: Syneto
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
This commit is contained in:
Rob Norris 2024-04-29 15:26:56 +10:00 committed by Tony Hutter
parent 5b5a514955
commit d28d2e3007
2 changed files with 87 additions and 25 deletions
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6
include/os/linux/spl/sys/kstat.h
View File

@ -21,6 +21,10 @@
* You should have received a copy of the GNU General Public License along
* with the SPL. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* Copyright (c) 2024-2025, Klara, Inc.
* Copyright (c) 2024-2025, Syneto
*/
#ifndef _SPL_KSTAT_H
#define _SPL_KSTAT_H
@ -90,6 +94,8 @@ typedef struct kstat_module {
struct list_head ksm_module_list; /* module linkage */
struct list_head ksm_kstat_list; /* list of kstat entries */
struct proc_dir_entry *ksm_proc; /* proc entry */
struct kstat_module *ksm_parent; /* parent module in hierarchy */
uint_t ksm_nchildren; /* number of child modules */
} kstat_module_t;
typedef struct kstat_raw_ops {

106
module/os/linux/spl/spl-kstat.c
View File

@ -27,6 +27,10 @@
* [1] https://illumos.org/man/1M/kstat
* [2] https://illumos.org/man/9f/kstat_create
*/
/*
* Copyright (c) 2024-2025, Klara, Inc.
* Copyright (c) 2024-2025, Syneto
*/
#include <linux/seq_file.h>
#include <sys/kstat.h>
@ -370,6 +374,8 @@ static const struct seq_operations kstat_seq_ops = {
static kstat_module_t *
kstat_find_module(char *name)
{
ASSERT(MUTEX_HELD(&kstat_module_lock));
kstat_module_t *module = NULL;
list_for_each_entry(module, &kstat_module_list, ksm_module_list) {
@ -380,33 +386,75 @@ kstat_find_module(char *name)
return (NULL);
}
static kstat_module_t *
kstat_create_module(char *name)
{
kstat_module_t *module;
struct proc_dir_entry *pde;
pde = proc_mkdir(name, proc_spl_kstat);
if (pde == NULL)
return (NULL);
module = kmem_alloc(sizeof (kstat_module_t), KM_SLEEP);
module->ksm_proc = pde;
strlcpy(module->ksm_name, name, KSTAT_STRLEN);
INIT_LIST_HEAD(&module->ksm_kstat_list);
list_add_tail(&module->ksm_module_list, &kstat_module_list);
return (module);
}
static void
kstat_delete_module(kstat_module_t *module)
{
ASSERT(MUTEX_HELD(&kstat_module_lock));
ASSERT(list_empty(&module->ksm_kstat_list));
remove_proc_entry(module->ksm_name, proc_spl_kstat);
ASSERT0(module->ksm_nchildren);
kstat_module_t *parent = module->ksm_parent;
char *p = module->ksm_name, *frag;
while (p != NULL && (frag = strsep(&p, "/"))) {}
remove_proc_entry(frag, parent ? parent->ksm_proc : proc_spl_kstat);
list_del(&module->ksm_module_list);
kmem_free(module, sizeof (kstat_module_t));
if (parent) {
parent->ksm_nchildren--;
if (parent->ksm_nchildren == 0 &&
list_empty(&parent->ksm_kstat_list))
kstat_delete_module(parent);
}
}
static kstat_module_t *
kstat_create_module(char *name)
{
ASSERT(MUTEX_HELD(&kstat_module_lock));
char buf[KSTAT_STRLEN];
kstat_module_t *module, *parent;
(void) strlcpy(buf, name, KSTAT_STRLEN);
parent = NULL;
char *p = buf, *frag;
while ((frag = strsep(&p, "/")) != NULL) {
module = kstat_find_module(buf);
if (module == NULL) {
struct proc_dir_entry *pde = proc_mkdir(frag,
parent ? parent->ksm_proc : proc_spl_kstat);
if (pde == NULL) {
cmn_err(CE_WARN, "kstat_create('%s'): "
"module dir create failed", buf);
if (parent)
kstat_delete_module(parent);
return (NULL);
}
module = kmem_zalloc(sizeof (kstat_module_t), KM_SLEEP);
module->ksm_proc = pde;
strlcpy(module->ksm_name, buf, KSTAT_STRLEN);
INIT_LIST_HEAD(&module->ksm_kstat_list);
list_add_tail(&module->ksm_module_list,
&kstat_module_list);
if (parent != NULL) {
module->ksm_parent = parent;
parent->ksm_nchildren++;
}
}
parent = module;
if (p != NULL)
p[-1] = '/';
}
return (module);
}
static int
@ -625,12 +673,20 @@ kstat_proc_entry_install(kstat_proc_entry_t *kpep, mode_t mode,
}
/*
* Only one entry by this name per-module, on failure the module
* shouldn't be deleted because we know it has at least one entry.
* We can only have one entry of this name per module. If one already
* exists, replace it by first removing the proc entry, then removing
* it from the list. The kstat itself lives on; it just can't be
* inspected through the filesystem.
*/
list_for_each_entry(tmp, &module->ksm_kstat_list, kpe_list) {
if (strncmp(tmp->kpe_name, kpep->kpe_name, KSTAT_STRLEN) == 0)
goto out;
if (tmp->kpe_proc != NULL &&
strncmp(tmp->kpe_name, kpep->kpe_name, KSTAT_STRLEN) == 0) {
ASSERT3P(tmp->kpe_owner, ==, module);
remove_proc_entry(tmp->kpe_name, module->ksm_proc);
tmp->kpe_proc = NULL;
list_del_init(&tmp->kpe_list);
break;
}
}
list_add_tail(&kpep->kpe_list, &module->ksm_kstat_list);