// SPDX-License-Identifier: GPL-2.0-only /* * net/sunrpc/cache.c * * Generic code for various authentication-related caches * used by sunrpc clients and servers. * * Copyright (C) 2002 Neil Brown */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "netns.h" #define RPCDBG_FACILITY RPCDBG_CACHE static bool cache_defer_req(struct cache_req *req, struct cache_head *item); static void cache_revisit_request(struct cache_head *item); static void cache_init(struct cache_head *h, struct cache_detail *detail) { time64_t now = seconds_since_boot(); INIT_HLIST_NODE(&h->cache_list); h->flags = 0; kref_init(&h->ref); h->expiry_time = now + CACHE_NEW_EXPIRY; if (now <= detail->flush_time) /* ensure it isn't already expired */ now = detail->flush_time + 1; h->last_refresh = now; } static void cache_fresh_unlocked(struct cache_head *head, struct cache_detail *detail); static struct cache_head *sunrpc_cache_find_rcu(struct cache_detail *detail, struct cache_head *key, int hash) { struct hlist_head *head = &detail->hash_table[hash]; struct cache_head *tmp; rcu_read_lock(); hlist_for_each_entry_rcu(tmp, head, cache_list) { if (!detail->match(tmp, key)) continue; if (test_bit(CACHE_VALID, &tmp->flags) && cache_is_expired(detail, tmp)) continue; tmp = cache_get_rcu(tmp); rcu_read_unlock(); return tmp; } rcu_read_unlock(); return NULL; } static void sunrpc_begin_cache_remove_entry(struct cache_head *ch, struct cache_detail *cd) { /* Must be called under cd->hash_lock */ hlist_del_init_rcu(&ch->cache_list); set_bit(CACHE_CLEANED, &ch->flags); cd->entries --; } static void sunrpc_end_cache_remove_entry(struct cache_head *ch, struct cache_detail *cd) { cache_fresh_unlocked(ch, cd); cache_put(ch, cd); } static struct cache_head *sunrpc_cache_add_entry(struct cache_detail *detail, struct cache_head *key, int hash) { struct cache_head *new, *tmp, *freeme = NULL; struct hlist_head *head = &detail->hash_table[hash]; new = detail->alloc(); if (!new) return NULL; /* must fully initialise 'new', else * we might get lose if we need to * cache_put it soon. */ cache_init(new, detail); detail->init(new, key); spin_lock(&detail->hash_lock); /* check if entry appeared while we slept */ hlist_for_each_entry_rcu(tmp, head, cache_list, lockdep_is_held(&detail->hash_lock)) { if (!detail->match(tmp, key)) continue; if (test_bit(CACHE_VALID, &tmp->flags) && cache_is_expired(detail, tmp)) { sunrpc_begin_cache_remove_entry(tmp, detail); trace_cache_entry_expired(detail, tmp); freeme = tmp; break; } cache_get(tmp); spin_unlock(&detail->hash_lock); cache_put(new, detail); return tmp; } hlist_add_head_rcu(&new->cache_list, head); detail->entries++; cache_get(new); spin_unlock(&detail->hash_lock); if (freeme) sunrpc_end_cache_remove_entry(freeme, detail); return new; } struct cache_head *sunrpc_cache_lookup_rcu(struct cache_detail *detail, struct cache_head *key, int hash) { struct cache_head *ret; ret = sunrpc_cache_find_rcu(detail, key, hash); if (ret) return ret; /* Didn't find anything, insert an empty entry */ return sunrpc_cache_add_entry(detail, key, hash); } EXPORT_SYMBOL_GPL(sunrpc_cache_lookup_rcu); static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch); static void cache_fresh_locked(struct cache_head *head, time64_t expiry, struct cache_detail *detail) { time64_t now = seconds_since_boot(); if (now <= detail->flush_time) /* ensure it isn't immediately treated as expired */ now = detail->flush_time + 1; head->expiry_time = expiry; head->last_refresh = now; smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */ set_bit(CACHE_VALID, &head->flags); } static void cache_fresh_unlocked(struct cache_head *head, struct cache_detail *detail) { if (test_and_clear_bit(CACHE_PENDING, &head->flags)) { cache_revisit_request(head); cache_dequeue(detail, head); } } static void cache_make_negative(struct cache_detail *detail, struct cache_head *h) { set_bit(CACHE_NEGATIVE, &h->flags); trace_cache_entry_make_negative(detail, h); } static void cache_entry_update(struct cache_detail *detail, struct cache_head *h, struct cache_head *new) { if (!test_bit(CACHE_NEGATIVE, &new->flags)) { detail->update(h, new); trace_cache_entry_update(detail, h); } else { cache_make_negative(detail, h); } } struct cache_head *sunrpc_cache_update(struct cache_detail *detail, struct cache_head *new, struct cache_head *old, int hash) { /* The 'old' entry is to be replaced by 'new'. * If 'old' is not VALID, we update it directly, * otherwise we need to replace it */ struct cache_head *tmp; if (!test_bit(CACHE_VALID, &old->flags)) { spin_lock(&detail->hash_lock); if (!test_bit(CACHE_VALID, &old->flags)) { cache_entry_update(detail, old, new); cache_fresh_locked(old, new->expiry_time, detail); spin_unlock(&detail->hash_lock); cache_fresh_unlocked(old, detail); return old; } spin_unlock(&detail->hash_lock); } /* We need to insert a new entry */ tmp = detail->alloc(); if (!tmp) { cache_put(old, detail); return NULL; } cache_init(tmp, detail); detail->init(tmp, old); spin_lock(&detail->hash_lock); cache_entry_update(detail, tmp, new); hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]); detail->entries++; cache_get(tmp); cache_fresh_locked(tmp, new->expiry_time, detail); cache_fresh_locked(old, 0, detail); spin_unlock(&detail->hash_lock); cache_fresh_unlocked(tmp, detail); cache_fresh_unlocked(old, detail); cache_put(old, detail); return tmp; } EXPORT_SYMBOL_GPL(sunrpc_cache_update); static inline int cache_is_valid(struct cache_head *h) { if (!test_bit(CACHE_VALID, &h->flags)) return -EAGAIN; else { /* entry is valid */ if (test_bit(CACHE_NEGATIVE, &h->flags)) return -ENOENT; else { /* * In combination with write barrier in * sunrpc_cache_update, ensures that anyone * using the cache entry after this sees the * updated contents: */ smp_rmb(); return 0; } } } static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h) { int rv; spin_lock(&detail->hash_lock); rv = cache_is_valid(h); if (rv == -EAGAIN) { cache_make_negative(detail, h); cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY, detail); rv = -ENOENT; } spin_unlock(&detail->hash_lock); cache_fresh_unlocked(h, detail); return rv; } /* * This is the generic cache management routine for all * the authentication caches. * It checks the currency of a cache item and will (later) * initiate an upcall to fill it if needed. * * * Returns 0 if the cache_head can be used, or cache_puts it and returns * -EAGAIN if upcall is pending and request has been queued * -ETIMEDOUT if upcall failed or request could not be queue or * upcall completed but item is still invalid (implying that * the cache item has been replaced with a newer one). * -ENOENT if cache entry was negative */ int cache_check(struct cache_detail *detail, struct cache_head *h, struct cache_req *rqstp) { int rv; time64_t refresh_age, age; /* First decide return status as best we can */ rv = cache_is_valid(h); /* now see if we want to start an upcall */ refresh_age = (h->expiry_time - h->last_refresh); age = seconds_since_boot() - h->last_refresh; if (rqstp == NULL) { if (rv == -EAGAIN) rv = -ENOENT; } else if (rv == -EAGAIN || (h->expiry_time != 0 && age > refresh_age/2)) { dprintk("RPC: Want update, refage=%lld, age=%lld\n", refresh_age, age); switch (detail->cache_upcall(detail, h)) { case -EINVAL: rv = try_to_negate_entry(detail, h); break; case -EAGAIN: cache_fresh_unlocked(h, detail); break; } } if (rv == -EAGAIN) { if (!cache_defer_req(rqstp, h)) { /* * Request was not deferred; handle it as best * we can ourselves: */ rv = cache_is_valid(h); if (rv == -EAGAIN) rv = -ETIMEDOUT; } } if (rv) cache_put(h, detail); return rv; } EXPORT_SYMBOL_GPL(cache_check); /* * caches need to be periodically cleaned. * For this we maintain a list of cache_detail and * a current pointer into that list and into the table * for that entry. * * Each time cache_clean is called it finds the next non-empty entry * in the current table and walks the list in that entry * looking for entries that can be removed. * * An entry gets removed if: * - The expiry is before current time * - The last_refresh time is before the flush_time for that cache * * later we might drop old entries with non-NEVER expiry if that table * is getting 'full' for some definition of 'full' * * The question of "how often to scan a table" is an interesting one * and is answered in part by the use of the "nextcheck" field in the * cache_detail. * When a scan of a table begins, the nextcheck field is set to a time * that is well into the future. * While scanning, if an expiry time is found that is earlier than the * current nextcheck time, nextcheck is set to that expiry time. * If the flush_time is ever set to a time earlier than the nextcheck * time, the nextcheck time is then set to that flush_time. * * A table is then only scanned if the current time is at least * the nextcheck time. * */ static LIST_HEAD(cache_list); static DEFINE_SPINLOCK(cache_list_lock); static struct cache_detail *current_detail; static int current_index; static void do_cache_clean(struct work_struct *work); static struct delayed_work cache_cleaner; void sunrpc_init_cache_detail(struct cache_detail *cd) { spin_lock_init(&cd->hash_lock); INIT_LIST_HEAD(&cd->queue); spin_lock(&cache_list_lock); cd->nextcheck = 0; cd->entries = 0; atomic_set(&cd->writers, 0); cd->last_close = 0; cd->last_warn = -1; list_add(&cd->others, &cache_list); spin_unlock(&cache_list_lock); /* start the cleaning process */ queue_delayed_work(system_power_efficient_wq, &cache_cleaner, 0); } EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail); void sunrpc_destroy_cache_detail(struct cache_detail *cd) { cache_purge(cd); spin_lock(&cache_list_lock); spin_lock(&cd->hash_lock); if (current_detail == cd) current_detail = NULL; list_del_init(&cd->others); spin_unlock(&cd->hash_lock); spin_unlock(&cache_list_lock); if (list_empty(&cache_list)) { /* module must be being unloaded so its safe to kill the worker */ cancel_delayed_work_sync(&cache_cleaner); } } EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail); /* clean cache tries to find something to clean * and cleans it. * It returns 1 if it cleaned something, * 0 if it didn't find anything this time * -1 if it fell off the end of the list. */ static int cache_clean(void) { int rv = 0; struct list_head *next; spin_lock(&cache_list_lock); /* find a suitable table if we don't already have one */ while (current_detail == NULL || current_index >= current_detail->hash_size) { if (current_detail) next = current_detail->others.next; else next = cache_list.next; if (next == &cache_list) { current_detail = NULL; spin_unlock(&cache_list_lock); return -1; } current_detail = list_entry(next, struct cache_detail, others); if (current_detail->nextcheck > seconds_since_boot()) current_index = current_detail->hash_size; else { current_index = 0; current_detail->nextcheck = seconds_since_boot()+30*60; } } /* find a non-empty bucket in the table */ while (current_detail && current_index < current_detail->hash_size && hlist_empty(¤t_detail->hash_table[current_index])) current_index++; /* find a cleanable entry in the bucket and clean it, or set to next bucket */ if (current_detail && current_index < current_detail->hash_size) { struct cache_head *ch = NULL; struct cache_detail *d; struct hlist_head *head; struct hlist_node *tmp; spin_lock(¤t_detail->hash_lock); /* Ok, now to clean this strand */ head = ¤t_detail->hash_table[current_index]; hlist_for_each_entry_safe(ch, tmp, head, cache_list) { if (current_detail->nextcheck > ch->expiry_time) current_detail->nextcheck = ch->expiry_time+1; if (!cache_is_expired(current_detail, ch)) continue; sunrpc_begin_cache_remove_entry(ch, current_detail); trace_cache_entry_expired(current_detail, ch); rv = 1; break; } spin_unlock(¤t_detail->hash_lock); d = current_detail; if (!ch) current_index ++; spin_unlock(&cache_list_lock); if (ch) sunrpc_end_cache_remove_entry(ch, d); } else spin_unlock(&cache_list_lock); return rv; } /* * We want to regularly clean the cache, so we need to schedule some work ... */ static void do_cache_clean(struct work_struct *work) { int delay = 5; if (cache_clean() == -1) delay = round_jiffies_relative(30*HZ); if (list_empty(&cache_list)) delay = 0; if (delay) queue_delayed_work(system_power_efficient_wq, &cache_cleaner, delay); } /* * Clean all caches promptly. This just calls cache_clean * repeatedly until we are sure that every cache has had a chance to * be fully cleaned */ void cache_flush(void) { while (cache_clean() != -1) cond_resched(); while (cache_clean() != -1) cond_resched(); } EXPORT_SYMBOL_GPL(cache_flush); void cache_purge(struct cache_detail *detail) { struct cache_head *ch = NULL; struct hlist_head *head = NULL; int i = 0; spin_lock(&detail->hash_lock); if (!detail->entries) { spin_unlock(&detail->hash_lock); return; } dprintk("RPC: %d entries in %s cache\n", detail->entries, detail->name); for (i = 0; i < detail->hash_size; i++) { head = &detail->hash_table[i]; while (!hlist_empty(head)) { ch = hlist_entry(head->first, struct cache_head, cache_list); sunrpc_begin_cache_remove_entry(ch, detail); spin_unlock(&detail->hash_lock); sunrpc_end_cache_remove_entry(ch, detail); spin_lock(&detail->hash_lock); } } spin_unlock(&detail->hash_lock); } EXPORT_SYMBOL_GPL(cache_purge); /* * Deferral and Revisiting of Requests. * * If a cache lookup finds a pending entry, we * need to defer the request and revisit it later. * All deferred requests are stored in a hash table, * indexed by "struct cache_head *". * As it may be wasteful to store a whole request * structure, we allow the request to provide a * deferred form, which must contain a * 'struct cache_deferred_req' * This cache_deferred_req contains a method to allow * it to be revisited when cache info is available */ #define DFR_HASHSIZE (PAGE_SIZE/sizeof(struct list_head)) #define DFR_HASH(item) ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE) #define DFR_MAX 300 /* ??? */ static DEFINE_SPINLOCK(cache_defer_lock); static LIST_HEAD(cache_defer_list); static struct hlist_head cache_defer_hash[DFR_HASHSIZE]; static int cache_defer_cnt; static void __unhash_deferred_req(struct cache_deferred_req *dreq) { hlist_del_init(&dreq->hash); if (!list_empty(&dreq->recent)) { list_del_init(&dreq->recent); cache_defer_cnt--; } } static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_head *item) { int hash = DFR_HASH(item); INIT_LIST_HEAD(&dreq->recent); hlist_add_head(&dreq->hash, &cache_defer_hash[hash]); } static void setup_deferral(struct cache_deferred_req *dreq, struct cache_head *item, int count_me) { dreq->item = item; spin_lock(&cache_defer_lock); __hash_deferred_req(dreq, item); if (count_me) { cache_defer_cnt++; list_add(&dreq->recent, &cache_defer_list); } spin_unlock(&cache_defer_lock); } struct thread_deferred_req { struct cache_deferred_req handle; struct completion completion; }; static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many) { struct thread_deferred_req *dr = container_of(dreq, struct thread_deferred_req, handle); complete(&dr->completion); } static void cache_wait_req(struct cache_req *req, struct cache_head *item) { struct thread_deferred_req sleeper; struct cache_deferred_req *dreq = &sleeper.handle; sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion); dreq->revisit = cache_restart_thread; setup_deferral(dreq, item, 0); if (!test_bit(CACHE_PENDING, &item->flags) || wait_for_completion_interruptible_timeout( &sleeper.completion, req->thread_wait) <= 0) { /* The completion wasn't completed, so we need * to clean up */ spin_lock(&cache_defer_lock); if (!hlist_unhashed(&sleeper.handle.hash)) { __unhash_deferred_req(&sleeper.handle); spin_unlock(&cache_defer_lock); } else { /* cache_revisit_request already removed * this from the hash table, but hasn't * called ->revisit yet. It will very soon * and we need to wait for it. */ spin_unlock(&cache_defer_lock); wait_for_completion(&sleeper.completion); } } } static void cache_limit_defers(void) { /* Make sure we haven't exceed the limit of allowed deferred * requests. */ struct cache_deferred_req *discard = NULL; if (cache_defer_cnt <= DFR_MAX) return; spin_lock(&cache_defer_lock); /* Consider removing either the first or the last */ if (cache_defer_cnt > DFR_MAX) { if (prandom_u32() & 1) discard = list_entry(cache_defer_list.next, struct cache_deferred_req, recent); else discard = list_entry(cache_defer_list.prev, struct cache_deferred_req, recent); __unhash_deferred_req(discard); } spin_unlock(&cache_defer_lock); if (discard) discard->revisit(discard, 1); } /* Return true if and only if a deferred request is queued. */ static bool cache_defer_req(struct cache_req *req, struct cache_head *item) { struct cache_deferred_req *dreq; if (req->thread_wait) { cache_wait_req(req, item); if (!test_bit(CACHE_PENDING, &item->flags)) return false; } dreq = req->defer(req); if (dreq == NULL) return false; setup_deferral(dreq, item, 1); if (!test_bit(CACHE_PENDING, &item->flags)) /* Bit could have been cleared before we managed to * set up the deferral, so need to revisit just in case */ cache_revisit_request(item); cache_limit_defers(); return true; } static void cache_revisit_request(struct cache_head *item) { struct cache_deferred_req *dreq; struct list_head pending; struct hlist_node *tmp; int hash = DFR_HASH(item); INIT_LIST_HEAD(&pending); spin_lock(&cache_defer_lock); hlist_for_each_entry_safe(dreq, tmp, &cache_defer_hash[hash], hash) if (dreq->item == item) { __unhash_deferred_req(dreq); list_add(&dreq->recent, &pending); } spin_unlock(&cache_defer_lock); while (!list_empty(&pending)) { dreq = list_entry(pending.next, struct cache_deferred_req, recent); list_del_init(&dreq->recent); dreq->revisit(dreq, 0); } } void cache_clean_deferred(void *owner) { struct cache_deferred_req *dreq, *tmp; struct list_head pending; INIT_LIST_HEAD(&pending); spin_lock(&cache_defer_lock); list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) { if (dreq->owner == owner) { __unhash_deferred_req(dreq); list_add(&dreq->recent, &pending); } } spin_unlock(&cache_defer_lock); while (!list_empty(&pending)) { dreq = list_entry(pending.next, struct cache_deferred_req, recent); list_del_init(&dreq->recent); dreq->revisit(dreq, 1); } } /* * communicate with user-space * * We have a magic /proc file - /proc/net/rpc//channel. * On read, you get a full request, or block. * On write, an update request is processed. * Poll works if anything to read, and always allows write. * * Implemented by linked list of requests. Each open file has * a ->private that also exists in this list. New requests are added * to the end and may wakeup and preceding readers. * New readers are added to the head. If, on read, an item is found with * CACHE_UPCALLING clear, we free it from the list. * */ static DEFINE_SPINLOCK(queue_lock); static DEFINE_MUTEX(queue_io_mutex); struct cache_queue { struct list_head list; int reader; /* if 0, then request */ }; struct cache_request { struct cache_queue q; struct cache_head *item; char * buf; int len; int readers; }; struct cache_reader { struct cache_queue q; int offset; /* if non-0, we have a refcnt on next request */ }; static int cache_request(struct cache_detail *detail, struct cache_request *crq) { char *bp = crq->buf; int len = PAGE_SIZE; detail->cache_request(detail, crq->item, &bp, &len); if (len < 0) return -EAGAIN; return PAGE_SIZE - len; } static ssize_t cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos, struct cache_detail *cd) { struct cache_reader *rp = filp->private_data; struct cache_request *rq; struct inode *inode = file_inode(filp); int err; if (count == 0) return 0; inode_lock(inode); /* protect against multiple concurrent * readers on this file */ again: spin_lock(&queue_lock); /* need to find next request */ while (rp->q.list.next != &cd->queue && list_entry(rp->q.list.next, struct cache_queue, list) ->reader) { struct list_head *next = rp->q.list.next; list_move(&rp->q.list, next); } if (rp->q.list.next == &cd->queue) { spin_unlock(&queue_lock); inode_unlock(inode); WARN_ON_ONCE(rp->offset); return 0; } rq = container_of(rp->q.list.next, struct cache_request, q.list); WARN_ON_ONCE(rq->q.reader); if (rp->offset == 0) rq->readers++; spin_unlock(&queue_lock); if (rq->len == 0) { err = cache_request(cd, rq); if (err < 0) goto out; rq->len = err; } if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) { err = -EAGAIN; spin_lock(&queue_lock); list_move(&rp->q.list, &rq->q.list); spin_unlock(&queue_lock); } else { if (rp->offset + count > rq->len) count = rq->len - rp->offset; err = -EFAULT; if (copy_to_user(buf, rq->buf + rp->offset, count)) goto out; rp->offset += count; if (rp->offset >= rq->len) { rp->offset = 0; spin_lock(&queue_lock); list_move(&rp->q.list, &rq->q.list); spin_unlock(&queue_lock); } err = 0; } out: if (rp->offset == 0) { /* need to release rq */ spin_lock(&queue_lock); rq->readers--; if (rq->readers == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) { list_del(&rq->q.list); spin_unlock(&queue_lock); cache_put(rq->item, cd); kfree(rq->buf); kfree(rq); } else spin_unlock(&queue_lock); } if (err == -EAGAIN) goto again; inode_unlock(inode); return err ? err : count; } static ssize_t cache_do_downcall(char *kaddr, const char __user *buf, size_t count, struct cache_detail *cd) { ssize_t ret; if (count == 0) return -EINVAL; if (copy_from_user(kaddr, buf, count)) return -EFAULT; kaddr[count] = '\0'; ret = cd->cache_parse(cd, kaddr, count); if (!ret) ret = count; return ret; } static ssize_t cache_slow_downcall(const char __user *buf, size_t count, struct cache_detail *cd) { static char write_buf[8192]; /* protected by queue_io_mutex */ ssize_t ret = -EINVAL; if (count >= sizeof(write_buf)) goto out; mutex_lock(&queue_io_mutex); ret = cache_do_downcall(write_buf, buf, count, cd); mutex_unlock(&queue_io_mutex); out: return ret; } static ssize_t cache_downcall(struct address_space *mapping, const char __user *buf, size_t count, struct cache_detail *cd) { struct page *page; char *kaddr; ssize_t ret = -ENOMEM; if (count >= PAGE_SIZE) goto out_slow; page = find_or_create_page(mapping, 0, GFP_KERNEL); if (!page) goto out_slow; kaddr = kmap(page); ret = cache_do_downcall(kaddr, buf, count, cd); kunmap(page); unlock_page(page); put_page(page); return ret; out_slow: return cache_slow_downcall(buf, count, cd); } static ssize_t cache_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos, struct cache_detail *cd) { struct address_space *mapping = filp->f_mapping; struct inode *inode = file_inode(filp); ssize_t ret = -EINVAL; if (!cd->cache_parse) goto out; inode_lock(inode); ret = cache_downcall(mapping, buf, count, cd); inode_unlock(inode); out: return ret; } static DECLARE_WAIT_QUEUE_HEAD(queue_wait); static __poll_t cache_poll(struct file *filp, poll_table *wait, struct cache_detail *cd) { __poll_t mask; struct cache_reader *rp = filp->private_data; struct cache_queue *cq; poll_wait(filp, &queue_wait, wait); /* alway allow write */ mask = EPOLLOUT | EPOLLWRNORM; if (!rp) return mask; spin_lock(&queue_lock); for (cq= &rp->q; &cq->list != &cd->queue; cq = list_entry(cq->list.next, struct cache_queue, list)) if (!cq->reader) { mask |= EPOLLIN | EPOLLRDNORM; break; } spin_unlock(&queue_lock); return mask; } static int cache_ioctl(struct inode *ino, struct file *filp, unsigned int cmd, unsigned long arg, struct cache_detail *cd) { int len = 0; struct cache_reader *rp = filp->private_data; struct cache_queue *cq; if (cmd != FIONREAD || !rp) return -EINVAL; spin_lock(&queue_lock); /* only find the length remaining in current request, * or the length of the next request */ for (cq= &rp->q; &cq->list != &cd->queue; cq = list_entry(cq->list.next, struct cache_queue, list)) if (!cq->reader) { struct cache_request *cr = container_of(cq, struct cache_request, q); len = cr->len - rp->offset; break; } spin_unlock(&queue_lock); return put_user(len, (int __user *)arg); } static int cache_open(struct inode *inode, struct file *filp, struct cache_detail *cd) { struct cache_reader *rp = NULL; if (!cd || !try_module_get(cd->owner)) return -EACCES; nonseekable_open(inode, filp); if (filp->f_mode & FMODE_READ) { rp = kmalloc(sizeof(*rp), GFP_KERNEL); if (!rp) { module_put(cd->owner); return -ENOMEM; } rp->offset = 0; rp->q.reader = 1; spin_lock(&queue_lock); list_add(&rp->q.list, &cd->queue); spin_unlock(&queue_lock); } if (filp->f_mode & FMODE_WRITE) atomic_inc(&cd->writers); filp->private_data = rp; return 0; } static int cache_release(struct inode *inode, struct file *filp, struct cache_detail *cd) { struct cache_reader *rp = filp->private_data; if (rp) { spin_lock(&queue_lock); if (rp->offset) { struct cache_queue *cq; for (cq= &rp->q; &cq->list != &cd->queue; cq = list_entry(cq->list.next, struct cache_queue, list)) if (!cq->reader) { container_of(cq, struct cache_request, q) ->readers--; break; } rp->offset = 0; } list_del(&rp->q.list); spin_unlock(&queue_lock); filp->private_data = NULL; kfree(rp); } if (filp->f_mode & FMODE_WRITE) { atomic_dec(&cd->writers); cd->last_close = seconds_since_boot(); } module_put(cd->owner); return 0; } static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch) { struct cache_queue *cq, *tmp; struct cache_request *cr; struct list_head dequeued; INIT_LIST_HEAD(&dequeued); spin_lock(&queue_lock); list_for_each_entry_safe(cq, tmp, &detail->queue, list) if (!cq->reader) { cr = container_of(cq, struct cache_request, q); if (cr->item != ch) continue; if (test_bit(CACHE_PENDING, &ch->flags)) /* Lost a race and it is pending again */ break; if (cr->readers != 0) continue; list_move(&cr->q.list, &dequeued); } spin_unlock(&queue_lock); while (!list_empty(&dequeued)) { cr = list_entry(dequeued.next, struct cache_request, q.list); list_del(&cr->q.list); cache_put(cr->item, detail); kfree(cr->buf); kfree(cr); } } /* * Support routines for text-based upcalls. * Fields are separated by spaces. * Fields are either mangled to quote space tab newline slosh with slosh * or a hexified with a leading \x * Record is terminated with newline. * */ void qword_add(char **bpp, int *lp, char *str) { char *bp = *bpp; int len = *lp; int ret; if (len < 0) return; ret = string_escape_str(str, bp, len, ESCAPE_OCTAL, "\\ \n\t"); if (ret >= len) { bp += len; len = -1; } else { bp += ret; len -= ret; *bp++ = ' '; len--; } *bpp = bp; *lp = len; } EXPORT_SYMBOL_GPL(qword_add); void qword_addhex(char **bpp, int *lp, char *buf, int blen) { char *bp = *bpp; int len = *lp; if (len < 0) return; if (len > 2) { *bp++ = '\\'; *bp++ = 'x'; len -= 2; while (blen && len >= 2) { bp = hex_byte_pack(bp, *buf++); len -= 2; blen--; } } if (blen || len<1) len = -1; else { *bp++ = ' '; len--; } *bpp = bp; *lp = len; } EXPORT_SYMBOL_GPL(qword_addhex); static void warn_no_listener(struct cache_detail *detail) { if (detail->last_warn != detail->last_close) { detail->last_warn = detail->last_close; if (detail->warn_no_listener) detail->warn_no_listener(detail, detail->last_close != 0); } } static bool cache_listeners_exist(struct cache_detail *detail) { if (atomic_read(&detail->writers)) return true; if (detail->last_close == 0) /* This cache was never opened */ return false; if (detail->last_close < seconds_since_boot() - 30) /* * We allow for the possibility that someone might * restart a userspace daemon without restarting the * server; but after 30 seconds, we give up. */ return false; return true; } /* * register an upcall request to user-space and queue it up for read() by the * upcall daemon. * * Each request is at most one page long. */ static int cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h) { char *buf; struct cache_request *crq; int ret = 0; if (test_bit(CACHE_CLEANED, &h->flags)) /* Too late to make an upcall */ return -EAGAIN; buf = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!buf) return -EAGAIN; crq = kmalloc(sizeof (*crq), GFP_KERNEL); if (!crq) { kfree(buf); return -EAGAIN; } crq->q.reader = 0; crq->buf = buf; crq->len = 0; crq->readers = 0; spin_lock(&queue_lock); if (test_bit(CACHE_PENDING, &h->flags)) { crq->item = cache_get(h); list_add_tail(&crq->q.list, &detail->queue); trace_cache_entry_upcall(detail, h); } else /* Lost a race, no longer PENDING, so don't enqueue */ ret = -EAGAIN; spin_unlock(&queue_lock); wake_up(&queue_wait); if (ret == -EAGAIN) { kfree(buf); kfree(crq); } return ret; } int sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h) { if (test_and_set_bit(CACHE_PENDING, &h->flags)) return 0; return cache_pipe_upcall(detail, h); } EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall); int sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail, struct cache_head *h) { if (!cache_listeners_exist(detail)) { warn_no_listener(detail); trace_cache_entry_no_listener(detail, h); return -EINVAL; } return sunrpc_cache_pipe_upcall(detail, h); } EXPORT_SYMBOL_GPL(sunrpc_cache_pipe_upcall_timeout); /* * parse a message from user-space and pass it * to an appropriate cache * Messages are, like requests, separated into fields by * spaces and dequotes as \xHEXSTRING or embedded \nnn octal * * Message is * reply cachename expiry key ... content.... * * key and content are both parsed by cache */ int qword_get(char **bpp, char *dest, int bufsize) { /* return bytes copied, or -1 on error */ char *bp = *bpp; int len = 0; while (*bp == ' ') bp++; if (bp[0] == '\\' && bp[1] == 'x') { /* HEX STRING */ bp += 2; while (len < bufsize - 1) { int h, l; h = hex_to_bin(bp[0]); if (h < 0) break; l = hex_to_bin(bp[1]); if (l < 0) break; *dest++ = (h << 4) | l; bp += 2; len++; } } else { /* text with \nnn octal quoting */ while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) { if (*bp == '\\' && isodigit(bp[1]) && (bp[1] <= '3') && isodigit(bp[2]) && isodigit(bp[3])) { int byte = (*++bp -'0'); bp++; byte = (byte << 3) | (*bp++ - '0'); byte = (byte << 3) | (*bp++ - '0'); *dest++ = byte; len++; } else { *dest++ = *bp++; len++; } } } if (*bp != ' ' && *bp != '\n' && *bp != '\0') return -1; while (*bp == ' ') bp++; *bpp = bp; *dest = '\0'; return len; } EXPORT_SYMBOL_GPL(qword_get); /* * support /proc/net/rpc/$CACHENAME/content * as a seqfile. * We call ->cache_show passing NULL for the item to * get a header, then pass each real item in the cache */ static void *__cache_seq_start(struct seq_file *m, loff_t *pos) { loff_t n = *pos; unsigned int hash, entry; struct cache_head *ch; struct cache_detail *cd = m->private; if (!n--) return SEQ_START_TOKEN; hash = n >> 32; entry = n & ((1LL<<32) - 1); hlist_for_each_entry_rcu(ch, &cd->hash_table[hash], cache_list) if (!entry--) return ch; n &= ~((1LL<<32) - 1); do { hash++; n += 1LL<<32; } while(hash < cd->hash_size && hlist_empty(&cd->hash_table[hash])); if (hash >= cd->hash_size) return NULL; *pos = n+1; return hlist_entry_safe(rcu_dereference_raw( hlist_first_rcu(&cd->hash_table[hash])), struct cache_head, cache_list); } static void *cache_seq_next(struct seq_file *m, void *p, loff_t *pos) { struct cache_head *ch = p; int hash = (*pos >> 32); struct cache_detail *cd = m->private; if (p == SEQ_START_TOKEN) hash = 0; else if (ch->cache_list.next == NULL) { hash++; *pos += 1LL<<32; } else { ++*pos; return hlist_entry_safe(rcu_dereference_raw( hlist_next_rcu(&ch->cache_list)), struct cache_head, cache_list); } *pos &= ~((1LL<<32) - 1); while (hash < cd->hash_size && hlist_empty(&cd->hash_table[hash])) { hash++; *pos += 1LL<<32; } if (hash >= cd->hash_size) return NULL; ++*pos; return hlist_entry_safe(rcu_dereference_raw( hlist_first_rcu(&cd->hash_table[hash])), struct cache_head, cache_list); } void *cache_seq_start_rcu(struct seq_file *m, loff_t *pos) __acquires(RCU) { rcu_read_lock(); return __cache_seq_start(m, pos); } EXPORT_SYMBOL_GPL(cache_seq_start_rcu); void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos) { return cache_seq_next(file, p, pos); } EXPORT_SYMBOL_GPL(cache_seq_next_rcu); void cache_seq_stop_rcu(struct seq_file *m, void *p) __releases(RCU) { rcu_read_unlock(); } EXPORT_SYMBOL_GPL(cache_seq_stop_rcu); static int c_show(struct seq_file *m, void *p) { struct cache_head *cp = p; struct cache_detail *cd = m->private; if (p == SEQ_START_TOKEN) return cd->cache_show(m, cd, NULL); ifdebug(CACHE) seq_printf(m, "# expiry=%lld refcnt=%d flags=%lx\n", convert_to_wallclock(cp->expiry_time), kref_read(&cp->ref), cp->flags); cache_get(cp); if (cache_check(cd, cp, NULL)) /* cache_check does a cache_put on failure */ seq_puts(m, "# "); else { if (cache_is_expired(cd, cp)) seq_puts(m, "# "); cache_put(cp, cd); } return cd->cache_show(m, cd, cp); } static const struct seq_operations cache_content_op = { .start = cache_seq_start_rcu, .next = cache_seq_next_rcu, .stop = cache_seq_stop_rcu, .show = c_show, }; static int content_open(struct inode *inode, struct file *file, struct cache_detail *cd) { struct seq_file *seq; int err; if (!cd || !try_module_get(cd->owner)) return -EACCES; err = seq_open(file, &cache_content_op); if (err) { module_put(cd->owner); return err; } seq = file->private_data; seq->private = cd; return 0; } static int content_release(struct inode *inode, struct file *file, struct cache_detail *cd) { int ret = seq_release(inode, file); module_put(cd->owner); return ret; } static int open_flush(struct inode *inode, struct file *file, struct cache_detail *cd) { if (!cd || !try_module_get(cd->owner)) return -EACCES; return nonseekable_open(inode, file); } static int release_flush(struct inode *inode, struct file *file, struct cache_detail *cd) { module_put(cd->owner); return 0; } static ssize_t read_flush(struct file *file, char __user *buf, size_t count, loff_t *ppos, struct cache_detail *cd) { char tbuf[22]; size_t len; len = snprintf(tbuf, sizeof(tbuf), "%llu\n", convert_to_wallclock(cd->flush_time)); return simple_read_from_buffer(buf, count, ppos, tbuf, len); } static ssize_t write_flush(struct file *file, const char __user *buf, size_t count, loff_t *ppos, struct cache_detail *cd) { char tbuf[20]; char *ep; time64_t now; if (*ppos || count > sizeof(tbuf)-1) return -EINVAL; if (copy_from_user(tbuf, buf, count)) return -EFAULT; tbuf[count] = 0; simple_strtoul(tbuf, &ep, 0); if (*ep && *ep != '\n') return -EINVAL; /* Note that while we check that 'buf' holds a valid number, * we always ignore the value and just flush everything. * Making use of the number leads to races. */ now = seconds_since_boot(); /* Always flush everything, so behave like cache_purge() * Do this by advancing flush_time to the current time, * or by one second if it has already reached the current time. * Newly added cache entries will always have ->last_refresh greater * that ->flush_time, so they don't get flushed prematurely. */ if (cd->flush_time >= now) now = cd->flush_time + 1; cd->flush_time = now; cd->nextcheck = now; cache_flush(); if (cd->flush) cd->flush(); *ppos += count; return count; } static ssize_t cache_read_procfs(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { struct cache_detail *cd = PDE_DATA(file_inode(filp)); return cache_read(filp, buf, count, ppos, cd); } static ssize_t cache_write_procfs(struct file *filp, const char __user *buf, size_t count, loff_t *ppos) { struct cache_detail *cd = PDE_DATA(file_inode(filp)); return cache_write(filp, buf, count, ppos, cd); } static __poll_t cache_poll_procfs(struct file *filp, poll_table *wait) { struct cache_detail *cd = PDE_DATA(file_inode(filp)); return cache_poll(filp, wait, cd); } static long cache_ioctl_procfs(struct file *filp, unsigned int cmd, unsigned long arg) { struct inode *inode = file_inode(filp); struct cache_detail *cd = PDE_DATA(inode); return cache_ioctl(inode, filp, cmd, arg, cd); } static int cache_open_procfs(struct inode *inode, struct file *filp) { struct cache_detail *cd = PDE_DATA(inode); return cache_open(inode, filp, cd); } static int cache_release_procfs(struct inode *inode, struct file *filp) { struct cache_detail *cd = PDE_DATA(inode); return cache_release(inode, filp, cd); } static const struct proc_ops cache_channel_proc_ops = { .proc_lseek = no_llseek, .proc_read = cache_read_procfs, .proc_write = cache_write_procfs, .proc_poll = cache_poll_procfs, .proc_ioctl = cache_ioctl_procfs, /* for FIONREAD */ .proc_open = cache_open_procfs, .proc_release = cache_release_procfs, }; static int content_open_procfs(struct inode *inode, struct file *filp) { struct cache_detail *cd = PDE_DATA(inode); return content_open(inode, filp, cd); } static int content_release_procfs(struct inode *inode, struct file *filp) { struct cache_detail *cd = PDE_DATA(inode); return content_release(inode, filp, cd); } static const struct proc_ops content_proc_ops = { .proc_open = content_open_procfs, .proc_read = seq_read, .proc_lseek = seq_lseek, .proc_release = content_release_procfs, }; static int open_flush_procfs(struct inode *inode, struct file *filp) { struct cache_detail *cd = PDE_DATA(inode); return open_flush(inode, filp, cd); } static int release_flush_procfs(struct inode *inode, struct file *filp) { struct cache_detail *cd = PDE_DATA(inode); return release_flush(inode, filp, cd); } static ssize_t read_flush_procfs(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { struct cache_detail *cd = PDE_DATA(file_inode(filp)); return read_flush(filp, buf, count, ppos, cd); } static ssize_t write_flush_procfs(struct file *filp, const char __user *buf, size_t count, loff_t *ppos) { struct cache_detail *cd = PDE_DATA(file_inode(filp)); return write_flush(filp, buf, count, ppos, cd); } static const struct proc_ops cache_flush_proc_ops = { .proc_open = open_flush_procfs, .proc_read = read_flush_procfs, .proc_write = write_flush_procfs, .proc_release = release_flush_procfs, .proc_lseek = no_llseek, }; static void remove_cache_proc_entries(struct cache_detail *cd) { if (cd->procfs) { proc_remove(cd->procfs); cd->procfs = NULL; } } #ifdef CONFIG_PROC_FS static int create_cache_proc_entries(struct cache_detail *cd, struct net *net) { struct proc_dir_entry *p; struct sunrpc_net *sn; sn = net_generic(net, sunrpc_net_id); cd->procfs = proc_mkdir(cd->name, sn->proc_net_rpc); if (cd->procfs == NULL) goto out_nomem; p = proc_create_data("flush", S_IFREG | 0600, cd->procfs, &cache_flush_proc_ops, cd); if (p == NULL) goto out_nomem; if (cd->cache_request || cd->cache_parse) { p = proc_create_data("channel", S_IFREG | 0600, cd->procfs, &cache_channel_proc_ops, cd); if (p == NULL) goto out_nomem; } if (cd->cache_show) { p = proc_create_data("content", S_IFREG | 0400, cd->procfs, &content_proc_ops, cd); if (p == NULL) goto out_nomem; } return 0; out_nomem: remove_cache_proc_entries(cd); return -ENOMEM; } #else /* CONFIG_PROC_FS */ static int create_cache_proc_entries(struct cache_detail *cd, struct net *net) { return 0; } #endif void __init cache_initialize(void) { INIT_DEFERRABLE_WORK(&cache_cleaner, do_cache_clean); } int cache_register_net(struct cache_detail *cd, struct net *net) { int ret; sunrpc_init_cache_detail(cd); ret = create_cache_proc_entries(cd, net); if (ret) sunrpc_destroy_cache_detail(cd); return ret; } EXPORT_SYMBOL_GPL(cache_register_net); void cache_unregister_net(struct cache_detail *cd, struct net *net) { remove_cache_proc_entries(cd); sunrpc_destroy_cache_detail(cd); } EXPORT_SYMBOL_GPL(cache_unregister_net); struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net) { struct cache_detail *cd; int i; cd = kmemdup(tmpl, sizeof(struct cache_detail), GFP_KERNEL); if (cd == NULL) return ERR_PTR(-ENOMEM); cd->hash_table = kcalloc(cd->hash_size, sizeof(struct hlist_head), GFP_KERNEL); if (cd->hash_table == NULL) { kfree(cd); return ERR_PTR(-ENOMEM); } for (i = 0; i < cd->hash_size; i++) INIT_HLIST_HEAD(&cd->hash_table[i]); cd->net = net; return cd; } EXPORT_SYMBOL_GPL(cache_create_net); void cache_destroy_net(struct cache_detail *cd, struct net *net) { kfree(cd->hash_table); kfree(cd); } EXPORT_SYMBOL_GPL(cache_destroy_net); static ssize_t cache_read_pipefs(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { struct cache_detail *cd = RPC_I(file_inode(filp))->private; return cache_read(filp, buf, count, ppos, cd); } static ssize_t cache_write_pipefs(struct file *filp, const char __user *buf, size_t count, loff_t *ppos) { struct cache_detail *cd = RPC_I(file_inode(filp))->private; return cache_write(filp, buf, count, ppos, cd); } static __poll_t cache_poll_pipefs(struct file *filp, poll_table *wait) { struct cache_detail *cd = RPC_I(file_inode(filp))->private; return cache_poll(filp, wait, cd); } static long cache_ioctl_pipefs(struct file *filp, unsigned int cmd, unsigned long arg) { struct inode *inode = file_inode(filp); struct cache_detail *cd = RPC_I(inode)->private; return cache_ioctl(inode, filp, cmd, arg, cd); } static int cache_open_pipefs(struct inode *inode, struct file *filp) { struct cache_detail *cd = RPC_I(inode)->private; return cache_open(inode, filp, cd); } static int cache_release_pipefs(struct inode *inode, struct file *filp) { struct cache_detail *cd = RPC_I(inode)->private; return cache_release(inode, filp, cd); } const struct file_operations cache_file_operations_pipefs = { .owner = THIS_MODULE, .llseek = no_llseek, .read = cache_read_pipefs, .write = cache_write_pipefs, .poll = cache_poll_pipefs, .unlocked_ioctl = cache_ioctl_pipefs, /* for FIONREAD */ .open = cache_open_pipefs, .release = cache_release_pipefs, }; static int content_open_pipefs(struct inode *inode, struct file *filp) { struct cache_detail *cd = RPC_I(inode)->private; return content_open(inode, filp, cd); } static int content_release_pipefs(struct inode *inode, struct file *filp) { struct cache_detail *cd = RPC_I(inode)->private; return content_release(inode, filp, cd); } const struct file_operations content_file_operations_pipefs = { .open = content_open_pipefs, .read = seq_read, .llseek = seq_lseek, .release = content_release_pipefs, }; static int open_flush_pipefs(struct inode *inode, struct file *filp) { struct cache_detail *cd = RPC_I(inode)->private; return open_flush(inode, filp, cd); } static int release_flush_pipefs(struct inode *inode, struct file *filp) { struct cache_detail *cd = RPC_I(inode)->private; return release_flush(inode, filp, cd); } static ssize_t read_flush_pipefs(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { struct cache_detail *cd = RPC_I(file_inode(filp))->private; return read_flush(filp, buf, count, ppos, cd); } static ssize_t write_flush_pipefs(struct file *filp, const char __user *buf, size_t count, loff_t *ppos) { struct cache_detail *cd = RPC_I(file_inode(filp))->private; return write_flush(filp, buf, count, ppos, cd); } const struct file_operations cache_flush_operations_pipefs = { .open = open_flush_pipefs, .read = read_flush_pipefs, .write = write_flush_pipefs, .release = release_flush_pipefs, .llseek = no_llseek, }; int sunrpc_cache_register_pipefs(struct dentry *parent, const char *name, umode_t umode, struct cache_detail *cd) { struct dentry *dir = rpc_create_cache_dir(parent, name, umode, cd); if (IS_ERR(dir)) return PTR_ERR(dir); cd->pipefs = dir; return 0; } EXPORT_SYMBOL_GPL(sunrpc_cache_register_pipefs); void sunrpc_cache_unregister_pipefs(struct cache_detail *cd) { if (cd->pipefs) { rpc_remove_cache_dir(cd->pipefs); cd->pipefs = NULL; } } EXPORT_SYMBOL_GPL(sunrpc_cache_unregister_pipefs); void sunrpc_cache_unhash(struct cache_detail *cd, struct cache_head *h) { spin_lock(&cd->hash_lock); if (!hlist_unhashed(&h->cache_list)){ sunrpc_begin_cache_remove_entry(h, cd); spin_unlock(&cd->hash_lock); sunrpc_end_cache_remove_entry(h, cd); } else spin_unlock(&cd->hash_lock); } EXPORT_SYMBOL_GPL(sunrpc_cache_unhash);