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-rw-r--r--fs/nfsd/filecache.c934
1 files changed, 934 insertions, 0 deletions
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
new file mode 100644
index 000000000000..ef55e9b1cd4e
--- /dev/null
+++ b/fs/nfsd/filecache.c
@@ -0,0 +1,934 @@
+/*
+ * Open file cache.
+ *
+ * (c) 2015 - Jeff Layton <jeff.layton@primarydata.com>
+ */
+
+#include <linux/hash.h>
+#include <linux/slab.h>
+#include <linux/file.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 "vfs.h"
+#include "nfsd.h"
+#include "nfsfh.h"
+#include "netns.h"
+#include "filecache.h"
+#include "trace.h"
+
+#define NFSDDBG_FACILITY NFSDDBG_FH
+
+/* FIXME: dynamically size this for the machine somehow? */
+#define NFSD_FILE_HASH_BITS 12
+#define NFSD_FILE_HASH_SIZE (1 << NFSD_FILE_HASH_BITS)
+#define NFSD_LAUNDRETTE_DELAY (2 * HZ)
+
+#define NFSD_FILE_LRU_RESCAN (0)
+#define NFSD_FILE_SHUTDOWN (1)
+#define NFSD_FILE_LRU_THRESHOLD (4096UL)
+#define NFSD_FILE_LRU_LIMIT (NFSD_FILE_LRU_THRESHOLD << 2)
+
+/* We only care about NFSD_MAY_READ/WRITE for this cache */
+#define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE)
+
+struct nfsd_fcache_bucket {
+ struct hlist_head nfb_head;
+ spinlock_t nfb_lock;
+ unsigned int nfb_count;
+ unsigned int nfb_maxcount;
+};
+
+static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
+
+static struct kmem_cache *nfsd_file_slab;
+static struct kmem_cache *nfsd_file_mark_slab;
+static struct nfsd_fcache_bucket *nfsd_file_hashtbl;
+static struct list_lru nfsd_file_lru;
+static long nfsd_file_lru_flags;
+static struct fsnotify_group *nfsd_file_fsnotify_group;
+static atomic_long_t nfsd_filecache_count;
+static struct delayed_work nfsd_filecache_laundrette;
+
+enum nfsd_file_laundrette_ctl {
+ NFSD_FILE_LAUNDRETTE_NOFLUSH = 0,
+ NFSD_FILE_LAUNDRETTE_MAY_FLUSH
+};
+
+static void
+nfsd_file_schedule_laundrette(enum nfsd_file_laundrette_ctl ctl)
+{
+ long count = atomic_long_read(&nfsd_filecache_count);
+
+ if (count == 0 || test_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags))
+ return;
+
+ /* Be more aggressive about scanning if over the threshold */
+ if (count > NFSD_FILE_LRU_THRESHOLD)
+ mod_delayed_work(system_wq, &nfsd_filecache_laundrette, 0);
+ else
+ schedule_delayed_work(&nfsd_filecache_laundrette, NFSD_LAUNDRETTE_DELAY);
+
+ if (ctl == NFSD_FILE_LAUNDRETTE_NOFLUSH)
+ return;
+
+ /* ...and don't delay flushing if we're out of control */
+ if (count >= NFSD_FILE_LRU_LIMIT)
+ flush_delayed_work(&nfsd_filecache_laundrette);
+}
+
+static void
+nfsd_file_slab_free(struct rcu_head *rcu)
+{
+ struct nfsd_file *nf = container_of(rcu, struct nfsd_file, nf_rcu);
+
+ put_cred(nf->nf_cred);
+ kmem_cache_free(nfsd_file_slab, nf);
+}
+
+static void
+nfsd_file_mark_free(struct fsnotify_mark *mark)
+{
+ struct nfsd_file_mark *nfm = container_of(mark, struct nfsd_file_mark,
+ nfm_mark);
+
+ kmem_cache_free(nfsd_file_mark_slab, nfm);
+}
+
+static struct nfsd_file_mark *
+nfsd_file_mark_get(struct nfsd_file_mark *nfm)
+{
+ if (!atomic_inc_not_zero(&nfm->nfm_ref))
+ return NULL;
+ return nfm;
+}
+
+static void
+nfsd_file_mark_put(struct nfsd_file_mark *nfm)
+{
+ if (atomic_dec_and_test(&nfm->nfm_ref)) {
+
+ fsnotify_destroy_mark(&nfm->nfm_mark, nfsd_file_fsnotify_group);
+ fsnotify_put_mark(&nfm->nfm_mark);
+ }
+}
+
+static struct nfsd_file_mark *
+nfsd_file_mark_find_or_create(struct nfsd_file *nf)
+{
+ int err;
+ struct fsnotify_mark *mark;
+ struct nfsd_file_mark *nfm = NULL, *new;
+ struct inode *inode = nf->nf_inode;
+
+ do {
+ mutex_lock(&nfsd_file_fsnotify_group->mark_mutex);
+ mark = fsnotify_find_mark(&inode->i_fsnotify_marks,
+ nfsd_file_fsnotify_group);
+ if (mark) {
+ nfm = nfsd_file_mark_get(container_of(mark,
+ struct nfsd_file_mark,
+ nfm_mark));
+ mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
+ fsnotify_put_mark(mark);
+ if (likely(nfm))
+ break;
+ } else
+ mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
+
+ /* allocate a new nfm */
+ new = kmem_cache_alloc(nfsd_file_mark_slab, GFP_KERNEL);
+ if (!new)
+ return NULL;
+ fsnotify_init_mark(&new->nfm_mark, nfsd_file_fsnotify_group);
+ new->nfm_mark.mask = FS_ATTRIB|FS_DELETE_SELF;
+ atomic_set(&new->nfm_ref, 1);
+
+ err = fsnotify_add_inode_mark(&new->nfm_mark, inode, 0);
+
+ /*
+ * If the add was successful, then return the object.
+ * Otherwise, we need to put the reference we hold on the
+ * nfm_mark. The fsnotify code will take a reference and put
+ * it on failure, so we can't just free it directly. It's also
+ * not safe to call fsnotify_destroy_mark on it as the
+ * mark->group will be NULL. Thus, we can't let the nfm_ref
+ * counter drive the destruction at this point.
+ */
+ if (likely(!err))
+ nfm = new;
+ else
+ fsnotify_put_mark(&new->nfm_mark);
+ } while (unlikely(err == -EEXIST));
+
+ return nfm;
+}
+
+static struct nfsd_file *
+nfsd_file_alloc(struct inode *inode, unsigned int may, unsigned int hashval,
+ struct net *net)
+{
+ struct nfsd_file *nf;
+
+ nf = kmem_cache_alloc(nfsd_file_slab, GFP_KERNEL);
+ if (nf) {
+ INIT_HLIST_NODE(&nf->nf_node);
+ INIT_LIST_HEAD(&nf->nf_lru);
+ nf->nf_file = NULL;
+ nf->nf_cred = get_current_cred();
+ nf->nf_net = net;
+ nf->nf_flags = 0;
+ nf->nf_inode = inode;
+ nf->nf_hashval = hashval;
+ atomic_set(&nf->nf_ref, 1);
+ nf->nf_may = may & NFSD_FILE_MAY_MASK;
+ if (may & NFSD_MAY_NOT_BREAK_LEASE) {
+ if (may & NFSD_MAY_WRITE)
+ __set_bit(NFSD_FILE_BREAK_WRITE, &nf->nf_flags);
+ if (may & NFSD_MAY_READ)
+ __set_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags);
+ }
+ nf->nf_mark = NULL;
+ trace_nfsd_file_alloc(nf);
+ }
+ return nf;
+}
+
+static bool
+nfsd_file_free(struct nfsd_file *nf)
+{
+ bool flush = false;
+
+ trace_nfsd_file_put_final(nf);
+ if (nf->nf_mark)
+ nfsd_file_mark_put(nf->nf_mark);
+ if (nf->nf_file) {
+ get_file(nf->nf_file);
+ filp_close(nf->nf_file, NULL);
+ fput(nf->nf_file);
+ flush = true;
+ }
+ call_rcu(&nf->nf_rcu, nfsd_file_slab_free);
+ return flush;
+}
+
+static bool
+nfsd_file_check_writeback(struct nfsd_file *nf)
+{
+ struct file *file = nf->nf_file;
+ struct address_space *mapping;
+
+ if (!file || !(file->f_mode & FMODE_WRITE))
+ return false;
+ mapping = file->f_mapping;
+ return mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) ||
+ mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK);
+}
+
+static int
+nfsd_file_check_write_error(struct nfsd_file *nf)
+{
+ struct file *file = nf->nf_file;
+
+ if (!file || !(file->f_mode & FMODE_WRITE))
+ return 0;
+ return filemap_check_wb_err(file->f_mapping, READ_ONCE(file->f_wb_err));
+}
+
+static bool
+nfsd_file_in_use(struct nfsd_file *nf)
+{
+ return nfsd_file_check_writeback(nf) ||
+ nfsd_file_check_write_error(nf);
+}
+
+static void
+nfsd_file_do_unhash(struct nfsd_file *nf)
+{
+ lockdep_assert_held(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
+
+ trace_nfsd_file_unhash(nf);
+
+ if (nfsd_file_check_write_error(nf))
+ nfsd_reset_boot_verifier(net_generic(nf->nf_net, nfsd_net_id));
+ --nfsd_file_hashtbl[nf->nf_hashval].nfb_count;
+ hlist_del_rcu(&nf->nf_node);
+ if (!list_empty(&nf->nf_lru))
+ list_lru_del(&nfsd_file_lru, &nf->nf_lru);
+ atomic_long_dec(&nfsd_filecache_count);
+}
+
+static bool
+nfsd_file_unhash(struct nfsd_file *nf)
+{
+ if (test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
+ nfsd_file_do_unhash(nf);
+ return true;
+ }
+ return false;
+}
+
+/*
+ * Return true if the file was unhashed.
+ */
+static bool
+nfsd_file_unhash_and_release_locked(struct nfsd_file *nf, struct list_head *dispose)
+{
+ lockdep_assert_held(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
+
+ trace_nfsd_file_unhash_and_release_locked(nf);
+ if (!nfsd_file_unhash(nf))
+ return false;
+ /* keep final reference for nfsd_file_lru_dispose */
+ if (atomic_add_unless(&nf->nf_ref, -1, 1))
+ return true;
+
+ list_add(&nf->nf_lru, dispose);
+ return true;
+}
+
+static int
+nfsd_file_put_noref(struct nfsd_file *nf)
+{
+ int count;
+ trace_nfsd_file_put(nf);
+
+ count = atomic_dec_return(&nf->nf_ref);
+ if (!count) {
+ WARN_ON(test_bit(NFSD_FILE_HASHED, &nf->nf_flags));
+ nfsd_file_free(nf);
+ }
+ return count;
+}
+
+void
+nfsd_file_put(struct nfsd_file *nf)
+{
+ bool is_hashed = test_bit(NFSD_FILE_HASHED, &nf->nf_flags) != 0;
+ bool unused = !nfsd_file_in_use(nf);
+
+ set_bit(NFSD_FILE_REFERENCED, &nf->nf_flags);
+ if (nfsd_file_put_noref(nf) == 1 && is_hashed && unused)
+ nfsd_file_schedule_laundrette(NFSD_FILE_LAUNDRETTE_MAY_FLUSH);
+}
+
+struct nfsd_file *
+nfsd_file_get(struct nfsd_file *nf)
+{
+ if (likely(atomic_inc_not_zero(&nf->nf_ref)))
+ return nf;
+ return NULL;
+}
+
+static void
+nfsd_file_dispose_list(struct list_head *dispose)
+{
+ struct nfsd_file *nf;
+
+ while(!list_empty(dispose)) {
+ nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
+ list_del(&nf->nf_lru);
+ nfsd_file_put_noref(nf);
+ }
+}
+
+static void
+nfsd_file_dispose_list_sync(struct list_head *dispose)
+{
+ bool flush = false;
+ struct nfsd_file *nf;
+
+ while(!list_empty(dispose)) {
+ nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
+ list_del(&nf->nf_lru);
+ if (!atomic_dec_and_test(&nf->nf_ref))
+ continue;
+ if (nfsd_file_free(nf))
+ flush = true;
+ }
+ if (flush)
+ flush_delayed_fput();
+}
+
+/*
+ * Note this can deadlock with nfsd_file_cache_purge.
+ */
+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)
+{
+ struct list_head *head = arg;
+ struct nfsd_file *nf = list_entry(item, struct nfsd_file, nf_lru);
+
+ /*
+ * Do a lockless refcount check. The hashtable holds one reference, so
+ * we look to see if anything else has a reference, or if any have
+ * been put since the shrinker last ran. Those don't get unhashed and
+ * released.
+ *
+ * Note that in the put path, we set the flag and then decrement the
+ * counter. Here we check the counter and then test and clear the flag.
+ * That order is deliberate to ensure that we can do this locklessly.
+ */
+ if (atomic_read(&nf->nf_ref) > 1)
+ goto out_skip;
+
+ /*
+ * Don't throw out files that are still undergoing I/O or
+ * that have uncleared errors pending.
+ */
+ if (nfsd_file_check_writeback(nf))
+ goto out_skip;
+
+ if (test_and_clear_bit(NFSD_FILE_REFERENCED, &nf->nf_flags))
+ goto out_rescan;
+
+ if (!test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags))
+ goto out_skip;
+
+ list_lru_isolate_move(lru, &nf->nf_lru, head);
+ return LRU_REMOVED;
+out_rescan:
+ set_bit(NFSD_FILE_LRU_RESCAN, &nfsd_file_lru_flags);
+out_skip:
+ return LRU_SKIP;
+}
+
+static void
+nfsd_file_lru_dispose(struct list_head *head)
+{
+ while(!list_empty(head)) {
+ struct nfsd_file *nf = list_first_entry(head,
+ struct nfsd_file, nf_lru);
+ list_del_init(&nf->nf_lru);
+ spin_lock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
+ nfsd_file_do_unhash(nf);
+ spin_unlock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
+ nfsd_file_put_noref(nf);
+ }
+}
+
+static unsigned long
+nfsd_file_lru_count(struct shrinker *s, struct shrink_control *sc)
+{
+ return list_lru_count(&nfsd_file_lru);
+}
+
+static unsigned long
+nfsd_file_lru_scan(struct shrinker *s, struct shrink_control *sc)
+{
+ LIST_HEAD(head);
+ unsigned long ret;
+
+ ret = list_lru_shrink_walk(&nfsd_file_lru, sc, nfsd_file_lru_cb, &head);
+ nfsd_file_lru_dispose(&head);
+ return ret;
+}
+
+static struct shrinker nfsd_file_shrinker = {
+ .scan_objects = nfsd_file_lru_scan,
+ .count_objects = nfsd_file_lru_count,
+ .seeks = 1,
+};
+
+static void
+__nfsd_file_close_inode(struct inode *inode, unsigned int hashval,
+ struct list_head *dispose)
+{
+ struct nfsd_file *nf;
+ struct hlist_node *tmp;
+
+ spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
+ hlist_for_each_entry_safe(nf, tmp, &nfsd_file_hashtbl[hashval].nfb_head, nf_node) {
+ if (inode == nf->nf_inode)
+ nfsd_file_unhash_and_release_locked(nf, dispose);
+ }
+ spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
+}
+
+/**
+ * nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file
+ * @inode: inode of the file to attempt to remove
+ *
+ * Walk the whole hash bucket, looking for any files that correspond to "inode".
+ * If any do, then unhash them and put the hashtable reference to them and
+ * destroy any that had their last reference put. Also ensure that any of the
+ * fputs also have their final __fput done as well.
+ */
+void
+nfsd_file_close_inode_sync(struct inode *inode)
+{
+ unsigned int hashval = (unsigned int)hash_long(inode->i_ino,
+ NFSD_FILE_HASH_BITS);
+ LIST_HEAD(dispose);
+
+ __nfsd_file_close_inode(inode, hashval, &dispose);
+ trace_nfsd_file_close_inode_sync(inode, hashval, !list_empty(&dispose));
+ nfsd_file_dispose_list_sync(&dispose);
+}
+
+/**
+ * nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file
+ * @inode: inode of the file to attempt to remove
+ *
+ * Walk the whole hash bucket, looking for any files that correspond to "inode".
+ * If any do, then unhash them and put the hashtable reference to them and
+ * destroy any that had their last reference put.
+ */
+static void
+nfsd_file_close_inode(struct inode *inode)
+{
+ unsigned int hashval = (unsigned int)hash_long(inode->i_ino,
+ NFSD_FILE_HASH_BITS);
+ LIST_HEAD(dispose);
+
+ __nfsd_file_close_inode(inode, hashval, &dispose);
+ trace_nfsd_file_close_inode(inode, hashval, !list_empty(&dispose));
+ nfsd_file_dispose_list(&dispose);
+}
+
+/**
+ * nfsd_file_delayed_close - close unused nfsd_files
+ * @work: dummy
+ *
+ * Walk the LRU list and close any entries that have not been used since
+ * the last scan.
+ *
+ * Note this can deadlock with nfsd_file_cache_purge.
+ */
+static void
+nfsd_file_delayed_close(struct work_struct *work)
+{
+ LIST_HEAD(head);
+
+ list_lru_walk(&nfsd_file_lru, nfsd_file_lru_cb, &head, LONG_MAX);
+
+ if (test_and_clear_bit(NFSD_FILE_LRU_RESCAN, &nfsd_file_lru_flags))
+ nfsd_file_schedule_laundrette(NFSD_FILE_LAUNDRETTE_NOFLUSH);
+
+ if (!list_empty(&head)) {
+ nfsd_file_lru_dispose(&head);
+ flush_delayed_fput();
+ }
+}
+
+static int
+nfsd_file_lease_notifier_call(struct notifier_block *nb, unsigned long arg,
+ void *data)
+{
+ struct file_lock *fl = data;
+
+ /* Only close files for F_SETLEASE leases */
+ if (fl->fl_flags & FL_LEASE)
+ nfsd_file_close_inode_sync(file_inode(fl->fl_file));
+ return 0;
+}
+
+static struct notifier_block nfsd_file_lease_notifier = {
+ .notifier_call = nfsd_file_lease_notifier_call,
+};
+
+static int
+nfsd_file_fsnotify_handle_event(struct fsnotify_group *group,
+ struct inode *inode,
+ u32 mask, const void *data, int data_type,
+ const struct qstr *file_name, u32 cookie,
+ struct fsnotify_iter_info *iter_info)
+{
+ trace_nfsd_file_fsnotify_handle_event(inode, mask);
+
+ /* Should be no marks on non-regular files */
+ if (!S_ISREG(inode->i_mode)) {
+ WARN_ON_ONCE(1);
+ return 0;
+ }
+
+ /* don't close files if this was not the last link */
+ if (mask & FS_ATTRIB) {
+ if (inode->i_nlink)
+ return 0;
+ }
+
+ nfsd_file_close_inode(inode);
+ return 0;
+}
+
+
+static const struct fsnotify_ops nfsd_file_fsnotify_ops = {
+ .handle_event = nfsd_file_fsnotify_handle_event,
+ .free_mark = nfsd_file_mark_free,
+};
+
+int
+nfsd_file_cache_init(void)
+{
+ int ret = -ENOMEM;
+ unsigned int i;
+
+ clear_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags);
+
+ if (nfsd_file_hashtbl)
+ return 0;
+
+ nfsd_file_hashtbl = kcalloc(NFSD_FILE_HASH_SIZE,
+ sizeof(*nfsd_file_hashtbl), GFP_KERNEL);
+ if (!nfsd_file_hashtbl) {
+ pr_err("nfsd: unable to allocate nfsd_file_hashtbl\n");
+ goto out_err;
+ }
+
+ nfsd_file_slab = kmem_cache_create("nfsd_file",
+ sizeof(struct nfsd_file), 0, 0, NULL);
+ if (!nfsd_file_slab) {
+ pr_err("nfsd: unable to create nfsd_file_slab\n");
+ goto out_err;
+ }
+
+ nfsd_file_mark_slab = kmem_cache_create("nfsd_file_mark",
+ sizeof(struct nfsd_file_mark), 0, 0, NULL);
+ if (!nfsd_file_mark_slab) {
+ pr_err("nfsd: unable to create nfsd_file_mark_slab\n");
+ goto out_err;
+ }
+
+
+ ret = list_lru_init(&nfsd_file_lru);
+ if (ret) {
+ pr_err("nfsd: failed to init nfsd_file_lru: %d\n", ret);
+ goto out_err;
+ }
+
+ ret = register_shrinker(&nfsd_file_shrinker);
+ if (ret) {
+ pr_err("nfsd: failed to register nfsd_file_shrinker: %d\n", ret);
+ goto out_lru;
+ }
+
+ ret = lease_register_notifier(&nfsd_file_lease_notifier);
+ if (ret) {
+ pr_err("nfsd: unable to register lease notifier: %d\n", ret);
+ goto out_shrinker;
+ }
+
+ nfsd_file_fsnotify_group = fsnotify_alloc_group(&nfsd_file_fsnotify_ops);
+ if (IS_ERR(nfsd_file_fsnotify_group)) {
+ pr_err("nfsd: unable to create fsnotify group: %ld\n",
+ PTR_ERR(nfsd_file_fsnotify_group));
+ nfsd_file_fsnotify_group = NULL;
+ goto out_notifier;
+ }
+
+ for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
+ INIT_HLIST_HEAD(&nfsd_file_hashtbl[i].nfb_head);
+ spin_lock_init(&nfsd_file_hashtbl[i].nfb_lock);
+ }
+
+ INIT_DELAYED_WORK(&nfsd_filecache_laundrette, nfsd_file_delayed_close);
+out:
+ return ret;
+out_notifier:
+ lease_unregister_notifier(&nfsd_file_lease_notifier);
+out_shrinker:
+ unregister_shrinker(&nfsd_file_shrinker);
+out_lru:
+ list_lru_destroy(&nfsd_file_lru);
+out_err:
+ kmem_cache_destroy(nfsd_file_slab);
+ nfsd_file_slab = NULL;
+ kmem_cache_destroy(nfsd_file_mark_slab);
+ nfsd_file_mark_slab = NULL;
+ kfree(nfsd_file_hashtbl);
+ nfsd_file_hashtbl = NULL;
+ goto out;
+}
+
+/*
+ * Note this can deadlock with nfsd_file_lru_cb.
+ */
+void
+nfsd_file_cache_purge(struct net *net)
+{
+ unsigned int i;
+ struct nfsd_file *nf;
+ struct hlist_node *next;
+ LIST_HEAD(dispose);
+ bool del;
+
+ if (!nfsd_file_hashtbl)
+ return;
+
+ for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
+ struct nfsd_fcache_bucket *nfb = &nfsd_file_hashtbl[i];
+
+ spin_lock(&nfb->nfb_lock);
+ hlist_for_each_entry_safe(nf, next, &nfb->nfb_head, nf_node) {
+ if (net && nf->nf_net != net)
+ continue;
+ del = nfsd_file_unhash_and_release_locked(nf, &dispose);
+
+ /*
+ * Deadlock detected! Something marked this entry as
+ * unhased, but hasn't removed it from the hash list.
+ */
+ WARN_ON_ONCE(!del);
+ }
+ spin_unlock(&nfb->nfb_lock);
+ nfsd_file_dispose_list(&dispose);
+ }
+}
+
+void
+nfsd_file_cache_shutdown(void)
+{
+ LIST_HEAD(dispose);
+
+ set_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags);
+
+ lease_unregister_notifier(&nfsd_file_lease_notifier);
+ unregister_shrinker(&nfsd_file_shrinker);
+ /*
+ * make sure all callers of nfsd_file_lru_cb are done before
+ * calling nfsd_file_cache_purge
+ */
+ cancel_delayed_work_sync(&nfsd_filecache_laundrette);
+ nfsd_file_cache_purge(NULL);
+ list_lru_destroy(&nfsd_file_lru);
+ rcu_barrier();
+ fsnotify_put_group(nfsd_file_fsnotify_group);
+ nfsd_file_fsnotify_group = NULL;
+ kmem_cache_destroy(nfsd_file_slab);
+ nfsd_file_slab = NULL;
+ fsnotify_wait_marks_destroyed();
+ kmem_cache_destroy(nfsd_file_mark_slab);
+ nfsd_file_mark_slab = NULL;
+ kfree(nfsd_file_hashtbl);
+ nfsd_file_hashtbl = NULL;
+}
+
+static bool
+nfsd_match_cred(const struct cred *c1, const struct cred *c2)
+{
+ int i;
+
+ if (!uid_eq(c1->fsuid, c2->fsuid))
+ return false;
+ if (!gid_eq(c1->fsgid, c2->fsgid))
+ return false;
+ if (c1->group_info == NULL || c2->group_info == NULL)
+ return c1->group_info == c2->group_info;
+ if (c1->group_info->ngroups != c2->group_info->ngroups)
+ return false;
+ for (i = 0; i < c1->group_info->ngroups; i++) {
+ if (!gid_eq(c1->group_info->gid[i], c2->group_info->gid[i]))
+ return false;
+ }
+ return true;
+}
+
+static struct nfsd_file *
+nfsd_file_find_locked(struct inode *inode, unsigned int may_flags,
+ unsigned int hashval, struct net *net)
+{
+ struct nfsd_file *nf;
+ unsigned char need = may_flags & NFSD_FILE_MAY_MASK;
+
+ hlist_for_each_entry_rcu(nf, &nfsd_file_hashtbl[hashval].nfb_head,
+ nf_node) {
+ if ((need & nf->nf_may) != need)
+ continue;
+ if (nf->nf_inode != inode)
+ continue;
+ if (nf->nf_net != net)
+ continue;
+ if (!nfsd_match_cred(nf->nf_cred, current_cred()))
+ continue;
+ if (nfsd_file_get(nf) != NULL)
+ return nf;
+ }
+ return NULL;
+}
+
+/**
+ * nfsd_file_is_cached - are there any cached open files for this fh?
+ * @inode: inode of the file to check
+ *
+ * Scan the hashtable for open files that match this fh. Returns true if there
+ * are any, and false if not.
+ */
+bool
+nfsd_file_is_cached(struct inode *inode)
+{
+ bool ret = false;
+ struct nfsd_file *nf;
+ unsigned int hashval;
+
+ hashval = (unsigned int)hash_long(inode->i_ino, NFSD_FILE_HASH_BITS);
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(nf, &nfsd_file_hashtbl[hashval].nfb_head,
+ nf_node) {
+ if (inode == nf->nf_inode) {
+ ret = true;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ trace_nfsd_file_is_cached(inode, hashval, (int)ret);
+ return ret;
+}
+
+__be32
+nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
+ unsigned int may_flags, struct nfsd_file **pnf)
+{
+ __be32 status;
+ struct net *net = SVC_NET(rqstp);
+ struct nfsd_file *nf, *new;
+ struct inode *inode;
+ unsigned int hashval;
+
+ /* FIXME: skip this if fh_dentry is already set? */
+ status = fh_verify(rqstp, fhp, S_IFREG,
+ may_flags|NFSD_MAY_OWNER_OVERRIDE);
+ if (status != nfs_ok)
+ return status;
+
+ inode = d_inode(fhp->fh_dentry);
+ hashval = (unsigned int)hash_long(inode->i_ino, NFSD_FILE_HASH_BITS);
+retry:
+ rcu_read_lock();
+ nf = nfsd_file_find_locked(inode, may_flags, hashval, net);
+ rcu_read_unlock();
+ if (nf)
+ goto wait_for_construction;
+
+ new = nfsd_file_alloc(inode, may_flags, hashval, net);
+ if (!new) {
+ trace_nfsd_file_acquire(rqstp, hashval, inode, may_flags,
+ NULL, nfserr_jukebox);
+ return nfserr_jukebox;
+ }
+
+ spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
+ nf = nfsd_file_find_locked(inode, may_flags, hashval, net);
+ if (nf == NULL)
+ goto open_file;
+ spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
+ nfsd_file_slab_free(&new->nf_rcu);
+
+wait_for_construction:
+ wait_on_bit(&nf->nf_flags, NFSD_FILE_PENDING, TASK_UNINTERRUPTIBLE);
+
+ /* Did construction of this file fail? */
+ if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
+ nfsd_file_put_noref(nf);
+ goto retry;
+ }
+
+ this_cpu_inc(nfsd_file_cache_hits);
+
+ if (!(may_flags & NFSD_MAY_NOT_BREAK_LEASE)) {
+ bool write = (may_flags & NFSD_MAY_WRITE);
+
+ if (test_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags) ||
+ (test_bit(NFSD_FILE_BREAK_WRITE, &nf->nf_flags) && write)) {
+ status = nfserrno(nfsd_open_break_lease(
+ file_inode(nf->nf_file), may_flags));
+ if (status == nfs_ok) {
+ clear_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags);
+ if (write)
+ clear_bit(NFSD_FILE_BREAK_WRITE,
+ &nf->nf_flags);
+ }
+ }
+ }
+out:
+ if (status == nfs_ok) {
+ *pnf = nf;
+ } else {
+ nfsd_file_put(nf);
+ nf = NULL;
+ }
+
+ trace_nfsd_file_acquire(rqstp, hashval, inode, may_flags, nf, status);
+ return status;
+open_file:
+ nf = new;
+ /* Take reference for the hashtable */
+ atomic_inc(&nf->nf_ref);
+ __set_bit(NFSD_FILE_HASHED, &nf->nf_flags);
+ __set_bit(NFSD_FILE_PENDING, &nf->nf_flags);
+ list_lru_add(&nfsd_file_lru, &nf->nf_lru);
+ hlist_add_head_rcu(&nf->nf_node, &nfsd_file_hashtbl[hashval].nfb_head);
+ ++nfsd_file_hashtbl[hashval].nfb_count;
+ nfsd_file_hashtbl[hashval].nfb_maxcount = max(nfsd_file_hashtbl[hashval].nfb_maxcount,
+ nfsd_file_hashtbl[hashval].nfb_count);
+ spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
+ atomic_long_inc(&nfsd_filecache_count);
+
+ nf->nf_mark = nfsd_file_mark_find_or_create(nf);
+ if (nf->nf_mark)
+ status = nfsd_open_verified(rqstp, fhp, S_IFREG,
+ may_flags, &nf->nf_file);
+ else
+ status = nfserr_jukebox;
+ /*
+ * If construction failed, or we raced with a call to unlink()
+ * then unhash.
+ */
+ if (status != nfs_ok || inode->i_nlink == 0) {
+ bool do_free;
+ spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
+ do_free = nfsd_file_unhash(nf);
+ spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
+ if (do_free)
+ nfsd_file_put_noref(nf);
+ }
+ clear_bit_unlock(NFSD_FILE_PENDING, &nf->nf_flags);
+ smp_mb__after_atomic();
+ wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING);
+ goto out;
+}
+
+/*
+ * 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.
+ */
+static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
+{
+ unsigned int i, count = 0, longest = 0;
+ unsigned long hits = 0;
+
+ /*
+ * No need for spinlocks here since we're not terribly interested in
+ * accuracy. We do take the nfsd_mutex simply to ensure that we
+ * don't end up racing with server shutdown
+ */
+ mutex_lock(&nfsd_mutex);
+ if (nfsd_file_hashtbl) {
+ for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
+ count += nfsd_file_hashtbl[i].nfb_count;
+ longest = max(longest, nfsd_file_hashtbl[i].nfb_count);
+ }
+ }
+ mutex_unlock(&nfsd_mutex);
+
+ for_each_possible_cpu(i)
+ hits += per_cpu(nfsd_file_cache_hits, i);
+
+ seq_printf(m, "total entries: %u\n", count);
+ seq_printf(m, "longest chain: %u\n", longest);
+ seq_printf(m, "cache hits: %lu\n", hits);
+ return 0;
+}
+
+int nfsd_file_cache_stats_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, nfsd_file_cache_stats_show, NULL);
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.