// SPDX-License-Identifier: GPL-2.0 /* * The NFSD open file cache. * * (c) 2015 - Jeff Layton <[email protected]> * * An nfsd_file object is a per-file collection of open state that binds * together: * - a struct file * * - a user credential * - a network namespace * - a read-ahead context * - monitoring for writeback errors * * nfsd_file objects are reference-counted. Consumers acquire a new * object via the nfsd_file_acquire API. They manage their interest in * the acquired object, and hence the object's reference count, via * nfsd_file_get and nfsd_file_put. There are two varieties of nfsd_file * object: * * * non-garbage-collected: When a consumer wants to precisely control * the lifetime of a file's open state, it acquires a non-garbage- * collected nfsd_file. The final nfsd_file_put releases the open * state immediately. * * * garbage-collected: When a consumer does not control the lifetime * of open state, it acquires a garbage-collected nfsd_file. The * final nfsd_file_put allows the open state to linger for a period * during which it may be re-used. */ #include <linux/hash.h> #include <linux/slab.h> #include <linux/file.h> #include <linux/pagemap.h> #include <linux/sched.h> #include <linux/list_lru.h> #include <linux/fsnotify_backend.h> #include <linux/fsnotify.h> #include <linux/seq_file.h> #include <linux/rhashtable.h> #include "vfs.h" #include "nfsd.h" #include "nfsfh.h" #include "netns.h" #include "filecache.h" #include "trace.h" #define NFSD_LAUNDRETTE_DELAY … #define NFSD_FILE_CACHE_UP … /* We only care about NFSD_MAY_READ/WRITE for this cache */ #define NFSD_FILE_MAY_MASK … static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits); static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions); static DEFINE_PER_CPU(unsigned long, nfsd_file_releases); static DEFINE_PER_CPU(unsigned long, nfsd_file_total_age); static DEFINE_PER_CPU(unsigned long, nfsd_file_evictions); struct nfsd_fcache_disposal { … }; static struct kmem_cache *nfsd_file_slab; static struct kmem_cache *nfsd_file_mark_slab; static struct list_lru nfsd_file_lru; static unsigned long nfsd_file_flags; static struct fsnotify_group *nfsd_file_fsnotify_group; static struct delayed_work nfsd_filecache_laundrette; static struct rhltable nfsd_file_rhltable ____cacheline_aligned_in_smp; static bool nfsd_match_cred(const struct cred *c1, const struct cred *c2) { … } static const struct rhashtable_params nfsd_file_rhash_params = …; static void nfsd_file_schedule_laundrette(void) { … } static void nfsd_file_slab_free(struct rcu_head *rcu) { … } static void nfsd_file_mark_free(struct fsnotify_mark *mark) { … } static struct nfsd_file_mark * nfsd_file_mark_get(struct nfsd_file_mark *nfm) { … } static void nfsd_file_mark_put(struct nfsd_file_mark *nfm) { … } static struct nfsd_file_mark * nfsd_file_mark_find_or_create(struct nfsd_file *nf, struct inode *inode) { … } static struct nfsd_file * nfsd_file_alloc(struct net *net, struct inode *inode, unsigned char need, bool want_gc) { … } /** * nfsd_file_check_write_error - check for writeback errors on a file * @nf: nfsd_file to check for writeback errors * * Check whether a nfsd_file has an unseen error. Reset the write * verifier if so. */ static void nfsd_file_check_write_error(struct nfsd_file *nf) { … } static void nfsd_file_hash_remove(struct nfsd_file *nf) { … } static bool nfsd_file_unhash(struct nfsd_file *nf) { … } static void nfsd_file_free(struct nfsd_file *nf) { … } static bool nfsd_file_check_writeback(struct nfsd_file *nf) { … } static bool nfsd_file_lru_add(struct nfsd_file *nf) { … } static bool nfsd_file_lru_remove(struct nfsd_file *nf) { … } struct nfsd_file * nfsd_file_get(struct nfsd_file *nf) { … } /** * nfsd_file_put - put the reference to a nfsd_file * @nf: nfsd_file of which to put the reference * * Put a reference to a nfsd_file. In the non-GC case, we just put the * reference immediately. In the GC case, if the reference would be * the last one, the put it on the LRU instead to be cleaned up later. */ void nfsd_file_put(struct nfsd_file *nf) { … } static void nfsd_file_dispose_list(struct list_head *dispose) { … } /** * nfsd_file_dispose_list_delayed - move list of dead files to net's freeme list * @dispose: list of nfsd_files to be disposed * * Transfers each file to the "freeme" list for its nfsd_net, to eventually * be disposed of by the per-net garbage collector. */ static void nfsd_file_dispose_list_delayed(struct list_head *dispose) { … } /** * nfsd_file_net_dispose - deal with nfsd_files waiting to be disposed. * @nn: nfsd_net in which to find files to be disposed. * * When files held open for nfsv3 are removed from the filecache, whether * due to memory pressure or garbage collection, they are queued to * a per-net-ns queue. This function completes the disposal, either * directly or by waking another nfsd thread to help with the work. */ void nfsd_file_net_dispose(struct nfsd_net *nn) { … } /** * nfsd_file_lru_cb - Examine an entry on the LRU list * @item: LRU entry to examine * @lru: controlling LRU * @lock: LRU list lock (unused) * @arg: dispose list * * Return values: * %LRU_REMOVED: @item was removed from the LRU * %LRU_ROTATE: @item is to be moved to the LRU tail * %LRU_SKIP: @item cannot be evicted */ static enum lru_status nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru, spinlock_t *lock, void *arg) __releases(lock) __acquires(lock) { … } static void nfsd_file_gc(void) { … } static void nfsd_file_gc_worker(struct work_struct *work) { … } static unsigned long nfsd_file_lru_count(struct shrinker *s, struct shrink_control *sc) { … } static unsigned long nfsd_file_lru_scan(struct shrinker *s, struct shrink_control *sc) { … } static struct shrinker *nfsd_file_shrinker; /** * nfsd_file_cond_queue - conditionally unhash and queue a nfsd_file * @nf: nfsd_file to attempt to queue * @dispose: private list to queue successfully-put objects * * Unhash an nfsd_file, try to get a reference to it, and then put that * reference. If it's the last reference, queue it to the dispose list. */ static void nfsd_file_cond_queue(struct nfsd_file *nf, struct list_head *dispose) __must_hold(RCU) { … } /** * nfsd_file_queue_for_close: try to close out any open nfsd_files for an inode * @inode: inode on which to close out nfsd_files * @dispose: list on which to gather nfsd_files to close out * * An nfsd_file represents a struct file being held open on behalf of nfsd. * An open file however can block other activity (such as leases), or cause * undesirable behavior (e.g. spurious silly-renames when reexporting NFS). * * This function is intended to find open nfsd_files when this sort of * conflicting access occurs and then attempt to close those files out. * * Populates the dispose list with entries that have already had their * refcounts go to zero. The actual free of an nfsd_file can be expensive, * so we leave it up to the caller whether it wants to wait or not. */ static void nfsd_file_queue_for_close(struct inode *inode, struct list_head *dispose) { … } /** * nfsd_file_close_inode - attempt a delayed close of a nfsd_file * @inode: inode of the file to attempt to remove * * Close out any open nfsd_files that can be reaped for @inode. The * actual freeing is deferred to the dispose_list_delayed infrastructure. * * This is used by the fsnotify callbacks and setlease notifier. */ static void nfsd_file_close_inode(struct inode *inode) { … } /** * nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file * @inode: inode of the file to attempt to remove * * Close out any open nfsd_files that can be reaped for @inode. The * nfsd_files are closed out synchronously. * * This is called from nfsd_rename and nfsd_unlink to avoid silly-renames * when reexporting NFS. */ void nfsd_file_close_inode_sync(struct inode *inode) { … } static int nfsd_file_lease_notifier_call(struct notifier_block *nb, unsigned long arg, void *data) { … } static struct notifier_block nfsd_file_lease_notifier = …; static int nfsd_file_fsnotify_handle_event(struct fsnotify_mark *mark, u32 mask, struct inode *inode, struct inode *dir, const struct qstr *name, u32 cookie) { … } static const struct fsnotify_ops nfsd_file_fsnotify_ops = …; int nfsd_file_cache_init(void) { … } /** * __nfsd_file_cache_purge: clean out the cache for shutdown * @net: net-namespace to shut down the cache (may be NULL) * * Walk the nfsd_file cache and close out any that match @net. If @net is NULL, * then close out everything. Called when an nfsd instance is being shut down, * and when the exports table is flushed. */ static void __nfsd_file_cache_purge(struct net *net) { … } static struct nfsd_fcache_disposal * nfsd_alloc_fcache_disposal(void) { … } static void nfsd_free_fcache_disposal(struct nfsd_fcache_disposal *l) { … } static void nfsd_free_fcache_disposal_net(struct net *net) { … } int nfsd_file_cache_start_net(struct net *net) { … } /** * nfsd_file_cache_purge - Remove all cache items associated with @net * @net: target net namespace * */ void nfsd_file_cache_purge(struct net *net) { … } void nfsd_file_cache_shutdown_net(struct net *net) { … } void nfsd_file_cache_shutdown(void) { … } static struct nfsd_file * nfsd_file_lookup_locked(const struct net *net, const struct cred *cred, struct inode *inode, unsigned char need, bool want_gc) { … } /** * nfsd_file_is_cached - are there any cached open files for this inode? * @inode: inode to check * * The lookup matches inodes in all net namespaces and is atomic wrt * nfsd_file_acquire(). * * Return values: * %true: filecache contains at least one file matching this inode * %false: filecache contains no files matching this inode */ bool nfsd_file_is_cached(struct inode *inode) { … } static __be32 nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct file *file, struct nfsd_file **pnf, bool want_gc) { … } /** * nfsd_file_acquire_gc - Get a struct nfsd_file with an open file * @rqstp: the RPC transaction being executed * @fhp: the NFS filehandle of the file to be opened * @may_flags: NFSD_MAY_ settings for the file * @pnf: OUT: new or found "struct nfsd_file" object * * The nfsd_file object returned by this API is reference-counted * and garbage-collected. The object is retained for a few * seconds after the final nfsd_file_put() in case the caller * wants to re-use it. * * Return values: * %nfs_ok - @pnf points to an nfsd_file with its reference * count boosted. * * On error, an nfsstat value in network byte order is returned. */ __be32 nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct nfsd_file **pnf) { … } /** * nfsd_file_acquire - Get a struct nfsd_file with an open file * @rqstp: the RPC transaction being executed * @fhp: the NFS filehandle of the file to be opened * @may_flags: NFSD_MAY_ settings for the file * @pnf: OUT: new or found "struct nfsd_file" object * * The nfsd_file_object returned by this API is reference-counted * but not garbage-collected. The object is unhashed after the * final nfsd_file_put(). * * Return values: * %nfs_ok - @pnf points to an nfsd_file with its reference * count boosted. * * On error, an nfsstat value in network byte order is returned. */ __be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct nfsd_file **pnf) { … } /** * nfsd_file_acquire_opened - Get a struct nfsd_file using existing open file * @rqstp: the RPC transaction being executed * @fhp: the NFS filehandle of the file just created * @may_flags: NFSD_MAY_ settings for the file * @file: cached, already-open file (may be NULL) * @pnf: OUT: new or found "struct nfsd_file" object * * Acquire a nfsd_file object that is not GC'ed. If one doesn't already exist, * and @file is non-NULL, use it to instantiate a new nfsd_file instead of * opening a new one. * * Return values: * %nfs_ok - @pnf points to an nfsd_file with its reference * count boosted. * * On error, an nfsstat value in network byte order is returned. */ __be32 nfsd_file_acquire_opened(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct file *file, struct nfsd_file **pnf) { … } /* * Note that fields may be added, removed or reordered in the future. Programs * scraping this file for info should test the labels to ensure they're * getting the correct field. */ int nfsd_file_cache_stats_show(struct seq_file *m, void *v) { … }
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