diff options
Diffstat (limited to 'fs/nfs/dir.c')
| -rw-r--r-- | fs/nfs/dir.c | 208 |
1 files changed, 167 insertions, 41 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 4a3d4ef76127..36d921f0c602 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -988,9 +988,13 @@ EXPORT_SYMBOL_GPL(nfs_force_lookup_revalidate); * A check for whether or not the parent directory has changed. * In the case it has, we assume that the dentries are untrustworthy * and may need to be looked up again. + * If rcu_walk prevents us from performing a full check, return 0. */ -static int nfs_check_verifier(struct inode *dir, struct dentry *dentry) +static int nfs_check_verifier(struct inode *dir, struct dentry *dentry, + int rcu_walk) { + int ret; + if (IS_ROOT(dentry)) return 1; if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE) @@ -998,7 +1002,11 @@ static int nfs_check_verifier(struct inode *dir, struct dentry *dentry) if (!nfs_verify_change_attribute(dir, dentry->d_time)) return 0; /* Revalidate nfsi->cache_change_attribute before we declare a match */ - if (nfs_revalidate_inode(NFS_SERVER(dir), dir) < 0) + if (rcu_walk) + ret = nfs_revalidate_inode_rcu(NFS_SERVER(dir), dir); + else + ret = nfs_revalidate_inode(NFS_SERVER(dir), dir); + if (ret < 0) return 0; if (!nfs_verify_change_attribute(dir, dentry->d_time)) return 0; @@ -1042,6 +1050,8 @@ int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags) out: return (inode->i_nlink == 0) ? -ENOENT : 0; out_force: + if (flags & LOOKUP_RCU) + return -ECHILD; ret = __nfs_revalidate_inode(server, inode); if (ret != 0) return ret; @@ -1054,6 +1064,9 @@ out_force: * * If parent mtime has changed, we revalidate, else we wait for a * period corresponding to the parent's attribute cache timeout value. + * + * If LOOKUP_RCU prevents us from performing a full check, return 1 + * suggesting a reval is needed. */ static inline int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry, @@ -1064,7 +1077,7 @@ int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry, return 0; if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) return 1; - return !nfs_check_verifier(dir, dentry); + return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU); } /* @@ -1088,21 +1101,30 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) struct nfs4_label *label = NULL; int error; - if (flags & LOOKUP_RCU) - return -ECHILD; - - parent = dget_parent(dentry); - dir = parent->d_inode; + if (flags & LOOKUP_RCU) { + parent = ACCESS_ONCE(dentry->d_parent); + dir = ACCESS_ONCE(parent->d_inode); + if (!dir) + return -ECHILD; + } else { + parent = dget_parent(dentry); + dir = parent->d_inode; + } nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE); inode = dentry->d_inode; if (!inode) { - if (nfs_neg_need_reval(dir, dentry, flags)) + if (nfs_neg_need_reval(dir, dentry, flags)) { + if (flags & LOOKUP_RCU) + return -ECHILD; goto out_bad; + } goto out_valid_noent; } if (is_bad_inode(inode)) { + if (flags & LOOKUP_RCU) + return -ECHILD; dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n", __func__, dentry); goto out_bad; @@ -1112,12 +1134,20 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags) goto out_set_verifier; /* Force a full look up iff the parent directory has changed */ - if (!nfs_is_exclusive_create(dir, flags) && nfs_check_verifier(dir, dentry)) { - if (nfs_lookup_verify_inode(inode, flags)) + if (!nfs_is_exclusive_create(dir, flags) && + nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) { + + if (nfs_lookup_verify_inode(inode, flags)) { + if (flags & LOOKUP_RCU) + return -ECHILD; goto out_zap_parent; + } goto out_valid; } + if (flags & LOOKUP_RCU) + return -ECHILD; + if (NFS_STALE(inode)) goto out_bad; @@ -1153,13 +1183,18 @@ out_set_verifier: /* Success: notify readdir to use READDIRPLUS */ nfs_advise_use_readdirplus(dir); out_valid_noent: - dput(parent); + if (flags & LOOKUP_RCU) { + if (parent != ACCESS_ONCE(dentry->d_parent)) + return -ECHILD; + } else + dput(parent); dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is valid\n", __func__, dentry); return 1; out_zap_parent: nfs_zap_caches(dir); out_bad: + WARN_ON(flags & LOOKUP_RCU); nfs_free_fattr(fattr); nfs_free_fhandle(fhandle); nfs4_label_free(label); @@ -1185,6 +1220,7 @@ out_zap_parent: __func__, dentry); return 0; out_error: + WARN_ON(flags & LOOKUP_RCU); nfs_free_fattr(fattr); nfs_free_fhandle(fhandle); nfs4_label_free(label); @@ -1529,14 +1565,9 @@ EXPORT_SYMBOL_GPL(nfs_atomic_open); static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags) { - struct dentry *parent = NULL; struct inode *inode; - struct inode *dir; int ret = 0; - if (flags & LOOKUP_RCU) - return -ECHILD; - if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY)) goto no_open; if (d_mountpoint(dentry)) @@ -1545,34 +1576,47 @@ static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags) goto no_open; inode = dentry->d_inode; - parent = dget_parent(dentry); - dir = parent->d_inode; /* We can't create new files in nfs_open_revalidate(), so we * optimize away revalidation of negative dentries. */ if (inode == NULL) { + struct dentry *parent; + struct inode *dir; + + if (flags & LOOKUP_RCU) { + parent = ACCESS_ONCE(dentry->d_parent); + dir = ACCESS_ONCE(parent->d_inode); + if (!dir) + return -ECHILD; + } else { + parent = dget_parent(dentry); + dir = parent->d_inode; + } if (!nfs_neg_need_reval(dir, dentry, flags)) ret = 1; + else if (flags & LOOKUP_RCU) + ret = -ECHILD; + if (!(flags & LOOKUP_RCU)) + dput(parent); + else if (parent != ACCESS_ONCE(dentry->d_parent)) + return -ECHILD; goto out; } /* NFS only supports OPEN on regular files */ if (!S_ISREG(inode->i_mode)) - goto no_open_dput; + goto no_open; /* We cannot do exclusive creation on a positive dentry */ if (flags & LOOKUP_EXCL) - goto no_open_dput; + goto no_open; /* Let f_op->open() actually open (and revalidate) the file */ ret = 1; out: - dput(parent); return ret; -no_open_dput: - dput(parent); no_open: return nfs_lookup_revalidate(dentry, flags); } @@ -2028,10 +2072,14 @@ static DEFINE_SPINLOCK(nfs_access_lru_lock); static LIST_HEAD(nfs_access_lru_list); static atomic_long_t nfs_access_nr_entries; +static unsigned long nfs_access_max_cachesize = ULONG_MAX; +module_param(nfs_access_max_cachesize, ulong, 0644); +MODULE_PARM_DESC(nfs_access_max_cachesize, "NFS access maximum total cache length"); + static void nfs_access_free_entry(struct nfs_access_entry *entry) { put_rpccred(entry->cred); - kfree(entry); + kfree_rcu(entry, rcu_head); smp_mb__before_atomic(); atomic_long_dec(&nfs_access_nr_entries); smp_mb__after_atomic(); @@ -2048,19 +2096,14 @@ static void nfs_access_free_list(struct list_head *head) } } -unsigned long -nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc) +static unsigned long +nfs_do_access_cache_scan(unsigned int nr_to_scan) { LIST_HEAD(head); struct nfs_inode *nfsi, *next; struct nfs_access_entry *cache; - int nr_to_scan = sc->nr_to_scan; - gfp_t gfp_mask = sc->gfp_mask; long freed = 0; - if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL) - return SHRINK_STOP; - spin_lock(&nfs_access_lru_lock); list_for_each_entry_safe(nfsi, next, &nfs_access_lru_list, access_cache_inode_lru) { struct inode *inode; @@ -2094,11 +2137,39 @@ remove_lru_entry: } unsigned long +nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc) +{ + int nr_to_scan = sc->nr_to_scan; + gfp_t gfp_mask = sc->gfp_mask; + + if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL) + return SHRINK_STOP; + return nfs_do_access_cache_scan(nr_to_scan); +} + + +unsigned long nfs_access_cache_count(struct shrinker *shrink, struct shrink_control *sc) { return vfs_pressure_ratio(atomic_long_read(&nfs_access_nr_entries)); } +static void +nfs_access_cache_enforce_limit(void) +{ + long nr_entries = atomic_long_read(&nfs_access_nr_entries); + unsigned long diff; + unsigned int nr_to_scan; + + if (nr_entries < 0 || nr_entries <= nfs_access_max_cachesize) + return; + nr_to_scan = 100; + diff = nr_entries - nfs_access_max_cachesize; + if (diff < nr_to_scan) + nr_to_scan = diff; + nfs_do_access_cache_scan(nr_to_scan); +} + static void __nfs_access_zap_cache(struct nfs_inode *nfsi, struct list_head *head) { struct rb_root *root_node = &nfsi->access_cache; @@ -2186,6 +2257,38 @@ out_zap: return -ENOENT; } +static int nfs_access_get_cached_rcu(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res) +{ + /* Only check the most recently returned cache entry, + * but do it without locking. + */ + struct nfs_inode *nfsi = NFS_I(inode); + struct nfs_access_entry *cache; + int err = -ECHILD; + struct list_head *lh; + + rcu_read_lock(); + if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS) + goto out; + lh = rcu_dereference(nfsi->access_cache_entry_lru.prev); + cache = list_entry(lh, struct nfs_access_entry, lru); + if (lh == &nfsi->access_cache_entry_lru || + cred != cache->cred) + cache = NULL; + if (cache == NULL) + goto out; + if (!nfs_have_delegated_attributes(inode) && + !time_in_range_open(jiffies, cache->jiffies, cache->jiffies + nfsi->attrtimeo)) + goto out; + res->jiffies = cache->jiffies; + res->cred = cache->cred; + res->mask = cache->mask; + err = 0; +out: + rcu_read_unlock(); + return err; +} + static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *set) { struct nfs_inode *nfsi = NFS_I(inode); @@ -2229,6 +2332,11 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set) cache->cred = get_rpccred(set->cred); cache->mask = set->mask; + /* The above field assignments must be visible + * before this item appears on the lru. We cannot easily + * use rcu_assign_pointer, so just force the memory barrier. + */ + smp_wmb(); nfs_access_add_rbtree(inode, cache); /* Update accounting */ @@ -2244,6 +2352,7 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set) &nfs_access_lru_list); spin_unlock(&nfs_access_lru_lock); } + nfs_access_cache_enforce_limit(); } EXPORT_SYMBOL_GPL(nfs_access_add_cache); @@ -2267,10 +2376,16 @@ static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask) trace_nfs_access_enter(inode); - status = nfs_access_get_cached(inode, cred, &cache); + status = nfs_access_get_cached_rcu(inode, cred, &cache); + if (status != 0) + status = nfs_access_get_cached(inode, cred, &cache); if (status == 0) goto out_cached; + status = -ECHILD; + if (mask & MAY_NOT_BLOCK) + goto out; + /* Be clever: ask server to check for all possible rights */ cache.mask = MAY_EXEC | MAY_WRITE | MAY_READ; cache.cred = cred; @@ -2321,9 +2436,6 @@ int nfs_permission(struct inode *inode, int mask) struct rpc_cred *cred; int res = 0; - if (mask & MAY_NOT_BLOCK) - return -ECHILD; - nfs_inc_stats(inode, NFSIOS_VFSACCESS); if ((mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) @@ -2350,12 +2462,23 @@ force_lookup: if (!NFS_PROTO(inode)->access) goto out_notsup; - cred = rpc_lookup_cred(); - if (!IS_ERR(cred)) { - res = nfs_do_access(inode, cred, mask); - put_rpccred(cred); - } else + /* Always try fast lookups first */ + rcu_read_lock(); + cred = rpc_lookup_cred_nonblock(); + if (!IS_ERR(cred)) + res = nfs_do_access(inode, cred, mask|MAY_NOT_BLOCK); + else res = PTR_ERR(cred); + rcu_read_unlock(); + if (res == -ECHILD && !(mask & MAY_NOT_BLOCK)) { + /* Fast lookup failed, try the slow way */ + cred = rpc_lookup_cred(); + if (!IS_ERR(cred)) { + res = nfs_do_access(inode, cred, mask); + put_rpccred(cred); + } else + res = PTR_ERR(cred); + } out: if (!res && (mask & MAY_EXEC) && !execute_ok(inode)) res = -EACCES; @@ -2364,6 +2487,9 @@ out: inode->i_sb->s_id, inode->i_ino, mask, res); return res; out_notsup: + if (mask & MAY_NOT_BLOCK) + return -ECHILD; + res = nfs_revalidate_inode(NFS_SERVER(inode), inode); if (res == 0) res = generic_permission(inode, mask); |