From d28d2e30079c1f453f9b9bf1bba876fe914ec901 Mon Sep 17 00:00:00 2001 From: Rob Norris Date: Mon, 29 Apr 2024 15:26:56 +1000 Subject: [PATCH] linux/kstat: allow multi-level module names 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 Reviewed-by: Alexander Motin Reviewed-by: Tony Hutter --- include/os/linux/spl/sys/kstat.h | 6 ++ module/os/linux/spl/spl-kstat.c | 106 +++++++++++++++++++++++-------- 2 files changed, 87 insertions(+), 25 deletions(-) diff --git a/include/os/linux/spl/sys/kstat.h b/include/os/linux/spl/sys/kstat.h index a9e9f1880..be58b455f 100644 --- a/include/os/linux/spl/sys/kstat.h +++ b/include/os/linux/spl/sys/kstat.h @@ -21,6 +21,10 @@ * You should have received a copy of the GNU General Public License along * with the SPL. If not, see . */ +/* + * 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 { diff --git a/module/os/linux/spl/spl-kstat.c b/module/os/linux/spl/spl-kstat.c index 04578204a..0a6125755 100644 --- a/module/os/linux/spl/spl-kstat.c +++ b/module/os/linux/spl/spl-kstat.c @@ -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 #include @@ -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);