diff options
Diffstat (limited to 'fs/dcache.c')
| -rw-r--r-- | fs/dcache.c | 577 |
1 files changed, 372 insertions, 205 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 32ceae3e6112..5c7cc953ac81 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -104,13 +104,22 @@ static unsigned int d_hash_shift __read_mostly; static struct hlist_bl_head *dentry_hashtable __read_mostly; -static inline struct hlist_bl_head *d_hash(const struct dentry *parent, +static inline struct hlist_bl_head *d_hash(unsigned int hash) +{ + return dentry_hashtable + (hash >> (32 - d_hash_shift)); +} + +#define IN_LOOKUP_SHIFT 10 +static struct hlist_bl_head in_lookup_hashtable[1 << IN_LOOKUP_SHIFT]; + +static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent, unsigned int hash) { hash += (unsigned long) parent / L1_CACHE_BYTES; - return dentry_hashtable + hash_32(hash, d_hash_shift); + return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT); } + /* Statistics gathering. */ struct dentry_stat_t dentry_stat = { .age_limit = 45, @@ -215,10 +224,9 @@ static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) { - const unsigned char *cs; /* * Be careful about RCU walk racing with rename: - * use ACCESS_ONCE to fetch the name pointer. + * use 'lockless_dereference' to fetch the name pointer. * * NOTE! Even if a rename will mean that the length * was not loaded atomically, we don't care. The @@ -232,8 +240,8 @@ static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *c * early because the data cannot match (there can * be no NUL in the ct/tcount data) */ - cs = ACCESS_ONCE(dentry->d_name.name); - smp_read_barrier_depends(); + const unsigned char *cs = lockless_dereference(dentry->d_name.name); + return dentry_string_cmp(cs, ct, tcount); } @@ -308,60 +316,23 @@ static void dentry_free(struct dentry *dentry) call_rcu(&dentry->d_u.d_rcu, __d_free); } -/** - * dentry_rcuwalk_invalidate - invalidate in-progress rcu-walk lookups - * @dentry: the target dentry - * After this call, in-progress rcu-walk path lookup will fail. This - * should be called after unhashing, and after changing d_inode (if - * the dentry has not already been unhashed). - */ -static inline void dentry_rcuwalk_invalidate(struct dentry *dentry) -{ - lockdep_assert_held(&dentry->d_lock); - /* Go through am invalidation barrier */ - write_seqcount_invalidate(&dentry->d_seq); -} - /* * Release the dentry's inode, using the filesystem - * d_iput() operation if defined. Dentry has no refcount - * and is unhashed. - */ -static void dentry_iput(struct dentry * dentry) - __releases(dentry->d_lock) - __releases(dentry->d_inode->i_lock) -{ - struct inode *inode = dentry->d_inode; - if (inode) { - __d_clear_type_and_inode(dentry); - hlist_del_init(&dentry->d_u.d_alias); - spin_unlock(&dentry->d_lock); - spin_unlock(&inode->i_lock); - if (!inode->i_nlink) - fsnotify_inoderemove(inode); - if (dentry->d_op && dentry->d_op->d_iput) - dentry->d_op->d_iput(dentry, inode); - else - iput(inode); - } else { - spin_unlock(&dentry->d_lock); - } -} - -/* - * Release the dentry's inode, using the filesystem - * d_iput() operation if defined. dentry remains in-use. + * d_iput() operation if defined. */ static void dentry_unlink_inode(struct dentry * dentry) __releases(dentry->d_lock) __releases(dentry->d_inode->i_lock) { struct inode *inode = dentry->d_inode; + bool hashed = !d_unhashed(dentry); - raw_write_seqcount_begin(&dentry->d_seq); + if (hashed) + raw_write_seqcount_begin(&dentry->d_seq); __d_clear_type_and_inode(dentry); hlist_del_init(&dentry->d_u.d_alias); - raw_write_seqcount_end(&dentry->d_seq); + if (hashed) + raw_write_seqcount_end(&dentry->d_seq); spin_unlock(&dentry->d_lock); spin_unlock(&inode->i_lock); if (!inode->i_nlink) @@ -477,13 +448,14 @@ void __d_drop(struct dentry *dentry) if (unlikely(IS_ROOT(dentry))) b = &dentry->d_sb->s_anon; else - b = d_hash(dentry->d_parent, dentry->d_name.hash); + b = d_hash(dentry->d_name.hash); hlist_bl_lock(b); __hlist_bl_del(&dentry->d_hash); dentry->d_hash.pprev = NULL; hlist_bl_unlock(b); - dentry_rcuwalk_invalidate(dentry); + /* After this call, in-progress rcu-walk path lookup will fail. */ + write_seqcount_invalidate(&dentry->d_seq); } } EXPORT_SYMBOL(__d_drop); @@ -496,6 +468,44 @@ void d_drop(struct dentry *dentry) } EXPORT_SYMBOL(d_drop); +static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent) +{ + struct dentry *next; + /* + * Inform d_walk() and shrink_dentry_list() that we are no longer + * attached to the dentry tree + */ + dentry->d_flags |= DCACHE_DENTRY_KILLED; + if (unlikely(list_empty(&dentry->d_child))) + return; + __list_del_entry(&dentry->d_child); + /* + * Cursors can move around the list of children. While we'd been + * a normal list member, it didn't matter - ->d_child.next would've + * been updated. However, from now on it won't be and for the + * things like d_walk() it might end up with a nasty surprise. + * Normally d_walk() doesn't care about cursors moving around - + * ->d_lock on parent prevents that and since a cursor has no children + * of its own, we get through it without ever unlocking the parent. + * There is one exception, though - if we ascend from a child that + * gets killed as soon as we unlock it, the next sibling is found + * using the value left in its ->d_child.next. And if _that_ + * pointed to a cursor, and cursor got moved (e.g. by lseek()) + * before d_walk() regains parent->d_lock, we'll end up skipping + * everything the cursor had been moved past. + * + * Solution: make sure that the pointer left behind in ->d_child.next + * points to something that won't be moving around. I.e. skip the + * cursors. + */ + while (dentry->d_child.next != &parent->d_subdirs) { + next = list_entry(dentry->d_child.next, struct dentry, d_child); + if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR))) + break; + dentry->d_child.next = next->d_child.next; + } +} + static void __dentry_kill(struct dentry *dentry) { struct dentry *parent = NULL; @@ -521,20 +531,13 @@ static void __dentry_kill(struct dentry *dentry) } /* if it was on the hash then remove it */ __d_drop(dentry); - __list_del_entry(&dentry->d_child); - /* - * Inform d_walk() that we are no longer attached to the - * dentry tree - */ - dentry->d_flags |= DCACHE_DENTRY_KILLED; + dentry_unlist(dentry, parent); if (parent) spin_unlock(&parent->d_lock); - dentry_iput(dentry); - /* - * dentry_iput drops the locks, at which point nobody (except - * transient RCU lookups) can reach this dentry. - */ - BUG_ON(dentry->d_lockref.count > 0); + if (dentry->d_inode) + dentry_unlink_inode(dentry); + else + spin_unlock(&dentry->d_lock); this_cpu_dec(nr_dentry); if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); @@ -578,7 +581,6 @@ static struct dentry *dentry_kill(struct dentry *dentry) failed: spin_unlock(&dentry->d_lock); - cpu_relax(); return dentry; /* try again with same dentry */ } @@ -752,6 +754,8 @@ void dput(struct dentry *dentry) return; repeat: + might_sleep(); + rcu_read_lock(); if (likely(fast_dput(dentry))) { rcu_read_unlock(); @@ -761,6 +765,8 @@ repeat: /* Slow case: now with the dentry lock held */ rcu_read_unlock(); + WARN_ON(d_in_lookup(dentry)); + /* Unreachable? Get rid of it */ if (unlikely(d_unhashed(dentry))) goto kill_it; @@ -783,8 +789,10 @@ repeat: kill_it: dentry = dentry_kill(dentry); - if (dentry) + if (dentry) { + cond_resched(); goto repeat; + } } EXPORT_SYMBOL(dput); @@ -1190,6 +1198,9 @@ resume: struct dentry *dentry = list_entry(tmp, struct dentry, d_child); next = tmp->next; + if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR)) + continue; + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); ret = enter(data, dentry); @@ -1546,6 +1557,7 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) { struct dentry *dentry; char *dname; + int err; dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); if (!dentry) @@ -1558,7 +1570,11 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) * be overwriting an internal NUL character */ dentry->d_iname[DNAME_INLINE_LEN-1] = 0; - if (name->len > DNAME_INLINE_LEN-1) { + if (unlikely(!name)) { + static const struct qstr anon = QSTR_INIT("/", 1); + name = &anon; + dname = dentry->d_iname; + } else if (name->len > DNAME_INLINE_LEN-1) { size_t size = offsetof(struct external_name, name[1]); struct external_name *p = kmalloc(size + name->len, GFP_KERNEL_ACCOUNT); @@ -1600,6 +1616,16 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) INIT_LIST_HEAD(&dentry->d_child); d_set_d_op(dentry, dentry->d_sb->s_d_op); + if (dentry->d_op && dentry->d_op->d_init) { + err = dentry->d_op->d_init(dentry); + if (err) { + if (dname_external(dentry)) + kfree(external_name(dentry)); + kmem_cache_free(dentry_cache, dentry); + return NULL; + } + } + this_cpu_inc(nr_dentry); return dentry; @@ -1619,7 +1645,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) struct dentry *dentry = __d_alloc(parent->d_sb, name); if (!dentry) return NULL; - + dentry->d_flags |= DCACHE_RCUACCESS; spin_lock(&parent->d_lock); /* * don't need child lock because it is not subject @@ -1634,6 +1660,16 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) } EXPORT_SYMBOL(d_alloc); +struct dentry *d_alloc_cursor(struct dentry * parent) +{ + struct dentry *dentry = __d_alloc(parent->d_sb, NULL); + if (dentry) { + dentry->d_flags |= DCACHE_RCUACCESS | DCACHE_DENTRY_CURSOR; + dentry->d_parent = dget(parent); + } + return dentry; +} + /** * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems) * @sb: the superblock @@ -1653,8 +1689,7 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name) struct qstr q; q.name = name; - q.len = strlen(name); - q.hash = full_name_hash(q.name, q.len); + q.hash_len = hashlen_string(parent, name); return d_alloc(parent, &q); } EXPORT_SYMBOL(d_alloc_name); @@ -1667,7 +1702,7 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | DCACHE_OP_DELETE | - DCACHE_OP_SELECT_INODE)); + DCACHE_OP_REAL)); dentry->d_op = op; if (!op) return; @@ -1683,8 +1718,8 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) dentry->d_flags |= DCACHE_OP_DELETE; if (op->d_prune) dentry->d_flags |= DCACHE_OP_PRUNE; - if (op->d_select_inode) - dentry->d_flags |= DCACHE_OP_SELECT_INODE; + if (op->d_real) + dentry->d_flags |= DCACHE_OP_REAL; } EXPORT_SYMBOL(d_set_d_op); @@ -1743,13 +1778,14 @@ type_determined: static void __d_instantiate(struct dentry *dentry, struct inode *inode) { unsigned add_flags = d_flags_for_inode(inode); + WARN_ON(d_in_lookup(dentry)); spin_lock(&dentry->d_lock); hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); raw_write_seqcount_begin(&dentry->d_seq); __d_set_inode_and_type(dentry, inode, add_flags); raw_write_seqcount_end(&dentry->d_seq); - __fsnotify_d_instantiate(dentry); + fsnotify_update_flags(dentry); spin_unlock(&dentry->d_lock); } @@ -1772,11 +1808,11 @@ void d_instantiate(struct dentry *entry, struct inode * inode) { BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); if (inode) { + security_d_instantiate(entry, inode); spin_lock(&inode->i_lock); __d_instantiate(entry, inode); spin_unlock(&inode->i_lock); } - security_d_instantiate(entry, inode); } EXPORT_SYMBOL(d_instantiate); @@ -1793,6 +1829,7 @@ int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) { BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); + security_d_instantiate(entry, inode); spin_lock(&inode->i_lock); if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) { spin_unlock(&inode->i_lock); @@ -1801,7 +1838,6 @@ int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) } __d_instantiate(entry, inode); spin_unlock(&inode->i_lock); - security_d_instantiate(entry, inode); return 0; } @@ -1812,9 +1848,7 @@ struct dentry *d_make_root(struct inode *root_inode) struct dentry *res = NULL; if (root_inode) { - static const struct qstr name = QSTR_INIT("/", 1); - - res = __d_alloc(root_inode->i_sb, &name); + res = __d_alloc(root_inode->i_sb, NULL); if (res) d_instantiate(res, root_inode); else @@ -1855,7 +1889,6 @@ EXPORT_SYMBOL(d_find_any_alias); static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected) { - static const struct qstr anonstring = QSTR_INIT("/", 1); struct dentry *tmp; struct dentry *res; unsigned add_flags; @@ -1869,12 +1902,13 @@ static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected) if (res) goto out_iput; - tmp = __d_alloc(inode->i_sb, &anonstring); + tmp = __d_alloc(inode->i_sb, NULL); if (!tmp) { res = ERR_PTR(-ENOMEM); goto out_iput; } + security_d_instantiate(tmp, inode); spin_lock(&inode->i_lock); res = __d_find_any_alias(inode); if (res) { @@ -1897,13 +1931,10 @@ static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected) hlist_bl_unlock(&tmp->d_sb->s_anon); spin_unlock(&tmp->d_lock); spin_unlock(&inode->i_lock); - security_d_instantiate(tmp, inode); return tmp; out_iput: - if (res && !IS_ERR(res)) - security_d_instantiate(res, inode); iput(inode); return res; } @@ -1972,68 +2003,53 @@ EXPORT_SYMBOL(d_obtain_root); struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, struct qstr *name) { - struct dentry *found; - struct dentry *new; + struct dentry *found, *res; /* * First check if a dentry matching the name already exists, * if not go ahead and create it now. */ found = d_hash_and_lookup(dentry->d_parent, name); - if (!found) { - new = d_alloc(dentry->d_parent, name); - if (!new) { - found = ERR_PTR(-ENOMEM); - } else { - found = d_splice_alias(inode, new); - if (found) { - dput(new); - return found; - } - return new; + if (found) { + iput(inode); + return found; + } + if (d_in_lookup(dentry)) { + found = d_alloc_parallel(dentry->d_parent, name, + dentry->d_wait); + if (IS_ERR(found) || !d_in_lookup(found)) { + iput(inode); + return found; } + } else { + found = d_alloc(dentry->d_parent, name); + if (!found) { + iput(inode); + return ERR_PTR(-ENOMEM); + } + } + res = d_splice_alias(inode, found); + if (res) { + dput(found); + return res; } - iput(inode); return found; } EXPORT_SYMBOL(d_add_ci); -/* - * Do the slow-case of the dentry name compare. - * - * Unlike the dentry_cmp() function, we need to atomically - * load the name and length information, so that the - * filesystem can rely on them, and can use the 'name' and - * 'len' information without worrying about walking off the - * end of memory etc. - * - * Thus the read_seqcount_retry() and the "duplicate" info - * in arguments (the low-level filesystem should not look - * at the dentry inode or name contents directly, since - * rename can change them while we're in RCU mode). - */ -enum slow_d_compare { - D_COMP_OK, - D_COMP_NOMATCH, - D_COMP_SEQRETRY, -}; -static noinline enum slow_d_compare slow_dentry_cmp( - const struct dentry *parent, - struct dentry *dentry, - unsigned int seq, - const struct qstr *name) +static inline bool d_same_name(const struct dentry *dentry, + const struct dentry *parent, + const struct qstr *name) { - int tlen = dentry->d_name.len; - const char *tname = dentry->d_name.name; - - if (read_seqcount_retry(&dentry->d_seq, seq)) { - cpu_relax(); - return D_COMP_SEQRETRY; + if (likely(!(parent->d_flags & DCACHE_OP_COMPARE))) { + if (dentry->d_name.len != name->len) + return false; + return dentry_cmp(dentry, name->name, name->len) == 0; } - if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) - return D_COMP_NOMATCH; - return D_COMP_OK; + return parent->d_op->d_compare(dentry, + dentry->d_name.len, dentry->d_name.name, + name) == 0; } /** @@ -2071,7 +2087,7 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent, { u64 hashlen = name->hash_len; const unsigned char *str = name->name; - struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); + struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen)); struct hlist_bl_node *node; struct dentry *dentry; @@ -2112,6 +2128,9 @@ seqretry: * dentry compare, we will do seqretries until it is stable, * and if we end up with a successful lookup, we actually * want to exit RCU lookup anyway. + * + * Note that raw_seqcount_begin still *does* smp_rmb(), so + * we are still guaranteed NUL-termination of ->d_name.name. */ seq = raw_seqcount_begin(&dentry->d_seq); if (dentry->d_parent != parent) @@ -2120,24 +2139,28 @@ seqretry: continue; if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { + int tlen; + const char *tname; if (dentry->d_name.hash != hashlen_hash(hashlen)) continue; - *seqp = seq; - switch (slow_dentry_cmp(parent, dentry, seq, name)) { - case D_COMP_OK: - return dentry; - case D_COMP_NOMATCH: - continue; - default: + tlen = dentry->d_name.len; + tname = dentry->d_name.name; + /* we want a consistent (name,len) pair */ + if (read_seqcount_retry(&dentry->d_seq, seq)) { + cpu_relax(); goto seqretry; } + if (parent->d_op->d_compare(dentry, + tlen, tname, name) != 0) + continue; + } else { + if (dentry->d_name.hash_len != hashlen) + continue; + if (dentry_cmp(dentry, str, hashlen_len(hashlen)) != 0) + continue; } - - if (dentry->d_name.hash_len != hashlen) - continue; *seqp = seq; - if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) - return dentry; + return dentry; } return NULL; } @@ -2185,10 +2208,8 @@ EXPORT_SYMBOL(d_lookup); */ struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) { - unsigned int len = name->len; unsigned int hash = name->hash; - const unsigned char *str = name->name; - struct hlist_bl_head *b = d_hash(parent, hash); + struct hlist_bl_head *b = d_hash(hash); struct hlist_bl_node *node; struct dentry *found = NULL; struct dentry *dentry; @@ -2226,21 +2247,8 @@ struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) if (d_unhashed(dentry)) goto next; - /* - * It is safe to compare names since d_move() cannot - * change the qstr (protected by d_lock). - */ - if (parent->d_flags & DCACHE_OP_COMPARE) { - int tlen = dentry->d_name.len; - const char *tname = dentry->d_name.name; - if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) - goto next; - } else { - if (dentry->d_name.len != len) - goto next; - if (dentry_cmp(dentry, str, len)) - goto next; - } + if (!d_same_name(dentry, parent, name)) + goto next; dentry->d_lockref.count++; found = dentry; @@ -2268,7 +2276,7 @@ struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) * calculate the standard hash first, as the d_op->d_hash() * routine may choose to leave the hash value unchanged. */ - name->hash = full_name_hash(name->name, name->len); + name->hash = full_name_hash(dir, name->name, name->len); if (dir->d_flags & DCACHE_OP_HASH) { int err = dir->d_op->d_hash(dir, name); if (unlikely(err < 0)) @@ -2331,20 +2339,15 @@ again: } EXPORT_SYMBOL(d_delete); -static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) +static void __d_rehash(struct dentry *entry) { + struct hlist_bl_head *b = d_hash(entry->d_name.hash); BUG_ON(!d_unhashed(entry)); hlist_bl_lock(b); - entry->d_flags |= DCACHE_RCUACCESS; hlist_bl_add_head_rcu(&entry->d_hash, b); hlist_bl_unlock(b); } -static void _d_rehash(struct dentry * entry) -{ - __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); -} - /** * d_rehash - add an entry back to the hash * @entry: dentry to add to the hash @@ -2355,22 +2358,186 @@ static void _d_rehash(struct dentry * entry) void d_rehash(struct dentry * entry) { spin_lock(&entry->d_lock); - _d_rehash(entry); + __d_rehash(entry); spin_unlock(&entry->d_lock); } EXPORT_SYMBOL(d_rehash); +static inline unsigned start_dir_add(struct inode *dir) +{ + + for (;;) { + unsigned n = dir->i_dir_seq; + if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n) + return n; + cpu_relax(); + } +} + +static inline void end_dir_add(struct inode *dir, unsigned n) +{ + smp_store_release(&dir->i_dir_seq, n + 2); +} + +static void d_wait_lookup(struct dentry *dentry) +{ + if (d_in_lookup(dentry)) { + DECLARE_WAITQUEUE(wait, current); + add_wait_queue(dentry->d_wait, &wait); + do { + set_current_state(TASK_UNINTERRUPTIBLE); + spin_unlock(&dentry->d_lock); + schedule(); + spin_lock(&dentry->d_lock); + } while (d_in_lookup(dentry)); + } +} + +struct dentry *d_alloc_parallel(struct dentry *parent, + const struct qstr *name, + wait_queue_head_t *wq) +{ + unsigned int hash = name->hash; + struct hlist_bl_head *b = in_lookup_hash(parent, hash); + struct hlist_bl_node *node; + struct dentry *new = d_alloc(parent, name); + struct dentry *dentry; + unsigned seq, r_seq, d_seq; + + if (unlikely(!new)) + return ERR_PTR(-ENOMEM); + +retry: + rcu_read_lock(); + seq = smp_load_acquire(&parent->d_inode->i_dir_seq) & ~1; + r_seq = read_seqbegin(&rename_lock); + dentry = __d_lookup_rcu(parent, name, &d_seq); + if (unlikely(dentry)) { + if (!lockref_get_not_dead(&dentry->d_lockref)) { + rcu_read_unlock(); + goto retry; + } + if (read_seqcount_retry(&dentry->d_seq, d_seq)) { + rcu_read_unlock(); + dput(dentry); + goto retry; + } + rcu_read_unlock(); + dput(new); + return dentry; + } + if (unlikely(read_seqretry(&rename_lock, r_seq))) { + rcu_read_unlock(); + goto retry; + } + hlist_bl_lock(b); + if (unlikely(parent->d_inode->i_dir_seq != seq)) { + hlist_bl_unlock(b); + rcu_read_unlock(); + goto retry; + } + /* + * No changes for the parent since the beginning of d_lookup(). + * Since all removals from the chain happen with hlist_bl_lock(), + * any potential in-lookup matches are going to stay here until + * we unlock the chain. All fields are stable in everything + * we encounter. + */ + hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) { + if (dentry->d_name.hash != hash) + continue; + if (dentry->d_parent != parent) + continue; + if (!d_same_name(dentry, parent, name)) + continue; + hlist_bl_unlock(b); + /* now we can try to grab a reference */ + if (!lockref_get_not_dead(&dentry->d_lockref)) { + rcu_read_unlock(); + goto retry; + } + + rcu_read_unlock(); + /* + * somebody is likely to be still doing lookup for it; + * wait for them to finish + */ + spin_lock(&dentry->d_lock); + d_wait_lookup(dentry); + /* + * it's not in-lookup anymore; in principle we should repeat + * everything from dcache lookup, but it's likely to be what + * d_lookup() would've found anyway. If it is, just return it; + * otherwise we really have to repeat the whole thing. + */ + if (unlikely(dentry->d_name.hash != hash)) + goto mismatch; + if (unlikely(dentry->d_parent != parent)) + goto mismatch; + if (unlikely(d_unhashed(dentry))) + goto mismatch; + if (unlikely(!d_same_name(dentry, parent, name))) + goto mismatch; + /* OK, it *is* a hashed match; return it */ + spin_unlock(&dentry->d_lock); + dput(new); + return dentry; + } + rcu_read_unlock(); + /* we can't take ->d_lock here; it's OK, though. */ + new->d_flags |= DCACHE_PAR_LOOKUP; + new->d_wait = wq; + hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b); + hlist_bl_unlock(b); + return new; +mismatch: + spin_unlock(&dentry->d_lock); + dput(dentry); + goto retry; +} +EXPORT_SYMBOL(d_alloc_parallel); + +void __d_lookup_done(struct dentry *dentry) +{ + struct hlist_bl_head *b = in_lookup_hash(dentry->d_parent, + dentry->d_name.hash); + hlist_bl_lock(b); + dentry->d_flags &= ~DCACHE_PAR_LOOKUP; + __hlist_bl_del(&dentry->d_u.d_in_lookup_hash); + wake_up_all(dentry->d_wait); + dentry->d_wait = NULL; + hlist_bl_unlock(b); + INIT_HLIST_NODE(&dentry->d_u.d_alias); + INIT_LIST_HEAD(&dentry->d_lru); +} +EXPORT_SYMBOL(__d_lookup_done); /* inode->i_lock held if inode is non-NULL */ static inline void __d_add(struct dentry *dentry, struct inode *inode) { + struct inode *dir = NULL; + unsigned n; + spin_lock(&dentry->d_lock); + if (unlikely(d_in_lookup(dentry))) { + dir = dentry->d_parent->d_inode; + n = start_dir_add(dir); + __d_lookup_done(dentry); + } if (inode) { - __d_instantiate(dentry, inode); + unsigned add_flags = d_flags_for_inode(inode); + hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); + raw_write_seqcount_begin(&dentry->d_seq); + __d_set_inode_and_type(dentry, inode, add_flags); + raw_write_seqcount_end(&dentry->d_seq); + fsnotify_update_flags(dentry); + } + __d_rehash(dentry); + if (dir) + end_dir_add(dir, n); + spin_unlock(&dentry->d_lock); + if (inode) spin_unlock(&inode->i_lock); - } - security_d_instantiate(dentry, inode); - d_rehash(dentry); } /** @@ -2384,8 +2551,10 @@ static inline void __d_add(struct dentry *dentry, struct inode *inode) void d_add(struct dentry *entry, struct inode *inode) { - if (inode) + if (inode) { + security_d_instantiate(entry, inode); spin_lock(&inode->i_lock); + } __d_add(entry, inode); } EXPORT_SYMBOL(d_add); @@ -2404,8 +2573,6 @@ EXPORT_SYMBOL(d_add); struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) { struct dentry *alias; - int len = entry->d_name.len; - const char *name = entry->d_name.name; unsigned int hash = entry->d_name.hash; spin_lock(&inode->i_lock); @@ -2419,9 +2586,7 @@ struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) continue; if (alias->d_parent != entry->d_parent) continue; - if (alias->d_name.len != len) - continue; - if (dentry_cmp(alias, name, len)) + if (!d_same_name(alias, entry->d_parent, &entry->d_name)) continue; spin_lock(&alias->d_lock); if (!d_unhashed(alias)) { @@ -2429,7 +2594,7 @@ struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) alias = NULL; } else { __dget_dlock(alias); - _d_rehash(alias); + __d_rehash(alias); spin_unlock(&alias->d_lock); } spin_unlock(&inode->i_lock); @@ -2454,7 +2619,7 @@ EXPORT_SYMBOL(d_exact_alias); * Parent inode i_mutex must be held over d_lookup and into this call (to * keep renames and concurrent inserts, and readdir(2) away). */ -void dentry_update_name_case(struct dentry *dentry, struct qstr *name) +void dentry_update_name_case(struct dentry *dentry, const struct qstr *name) { BUG_ON(!inode_is_locked(dentry->d_parent->d_inode)); BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ @@ -2595,6 +2760,8 @@ static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target) static void __d_move(struct dentry *dentry, struct dentry *target, bool exchange) { + struct inode *dir = NULL; + unsigned n; if (!dentry->d_inode) printk(KERN_WARNING "VFS: moving negative dcache entry\n"); @@ -2602,28 +2769,19 @@ static void __d_move(struct dentry *dentry, struct dentry *target, BUG_ON(d_ancestor(target, dentry)); dentry_lock_for_move(dentry, target); + if (unlikely(d_in_lookup(target))) { + dir = target->d_parent->d_inode; + n = start_dir_add(dir); + __d_lookup_done(target); + } write_seqcount_begin(&dentry->d_seq); write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED); + /* unhash both */ /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ - - /* - * Move the dentry to the target hash queue. Don't bother checking - * for the same hash queue because of how unlikely it is. - */ __d_drop(dentry); - __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); - - /* - * Unhash the target (d_delete() is not usable here). If exchanging - * the two dentries, then rehash onto the other's hash queue. - */ __d_drop(target); - if (exchange) { - __d_rehash(target, - d_hash(dentry->d_parent, dentry->d_name.hash)); - } /* Switch the names.. */ if (exchange) @@ -2631,9 +2789,15 @@ static void __d_move(struct dentry *dentry, struct dentry *target, else copy_name(dentry, target); + /* rehash in new place(s) */ + __d_rehash(dentry); + if (exchange) + __d_rehash(target); + /* ... and switch them in the tree */ if (IS_ROOT(dentry)) { /* splicing a tree */ + dentry->d_flags |= DCACHE_RCUACCESS; dentry->d_parent = target->d_parent; target->d_parent = target; list_del_init(&target->d_child); @@ -2644,13 +2808,15 @@ static void __d_move(struct dentry *dentry, struct dentry *target, list_move(&target->d_child, &target->d_parent->d_subdirs); list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); if (exchange) - fsnotify_d_move(target); - fsnotify_d_move(dentry); + fsnotify_update_flags(target); + fsnotify_update_flags(dentry); } write_seqcount_end(&target->d_seq); write_seqcount_end(&dentry->d_seq); + if (dir) + end_dir_add(dir, n); dentry_unlock_for_move(dentry, target); } @@ -2721,7 +2887,8 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) static int __d_unalias(struct inode *inode, struct dentry *dentry, struct dentry *alias) { - struct mutex *m1 = NULL, *m2 = NULL; + struct mutex *m1 = NULL; + struct rw_semaphore *m2 = NULL; int ret = -ESTALE; /* If alias and dentry share a parent, then no extra locks required */ @@ -2732,15 +2899,15 @@ static int __d_unalias(struct inode *inode, if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) goto out_err; m1 = &dentry->d_sb->s_vfs_rename_mutex; - if (!inode_trylock(alias->d_parent->d_inode)) + if (!inode_trylock_shared(alias->d_parent->d_inode)) goto out_err; - m2 = &alias->d_parent->d_inode->i_mutex; + m2 = &alias->d_parent->d_inode->i_rwsem; out_unalias: __d_move(alias, dentry, false); ret = 0; out_err: if (m2) - mutex_unlock(m2); + up_read(m2); if (m1) mutex_unlock(m1); return ret; @@ -2779,6 +2946,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) if (!inode) goto out; + security_d_instantiate(dentry, inode); spin_lock(&inode->i_lock); if (S_ISDIR(inode->i_mode)) { struct dentry *new = __d_find_any_alias(inode); @@ -2806,7 +2974,6 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) } else { __d_move(new, dentry, false); write_sequnlock(&rename_lock); - security_d_instantiate(new, inode); } iput(inode); return new; @@ -2846,7 +3013,7 @@ static int prepend(char **buffer, int *buflen, const char *str, int namelen) * Data dependency barrier is needed to make sure that we see that terminating * NUL. Alpha strikes again, film at 11... */ -static int prepend_name(char **buffer, int *buflen, struct qstr *name) +static int prepend_name(char **buffer, int *buflen, const struct qstr *name) { const char *dname = ACCESS_ONCE(name->name); u32 dlen = ACCESS_ONCE(name->len); |