fs: scale inode alias list
Nick Piggin [Fri, 7 Jan 2011 06:49:35 +0000 (17:49 +1100)]
Add a new lock, dcache_inode_lock, to protect the inode's i_dentry list
from concurrent modification. d_alias is also protected by d_lock.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

fs/9p/vfs_inode.c
fs/affs/amigaffs.c
fs/cifs/inode.c
fs/dcache.c
fs/exportfs/expfs.c
fs/nfs/getroot.c
fs/notify/fsnotify.c
fs/ocfs2/dcache.c
include/linux/dcache.h

index 34bf71b..47dfd5d 100644 (file)
@@ -271,9 +271,11 @@ static struct dentry *v9fs_dentry_from_dir_inode(struct inode *inode)
        struct dentry *dentry;
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        /* Directory should have only one entry. */
        BUG_ON(S_ISDIR(inode->i_mode) && !list_is_singular(&inode->i_dentry));
        dentry = list_entry(inode->i_dentry.next, struct dentry, d_alias);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
        return dentry;
 }
index 7d0f0a3..2321cc9 100644 (file)
@@ -129,6 +129,7 @@ affs_fix_dcache(struct dentry *dentry, u32 entry_ino)
        struct list_head *head, *next;
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        head = &inode->i_dentry;
        next = head->next;
        while (next != head) {
@@ -139,6 +140,7 @@ affs_fix_dcache(struct dentry *dentry, u32 entry_ino)
                }
                next = next->next;
        }
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 }
 
index 589f3e3..0036983 100644 (file)
@@ -810,12 +810,15 @@ inode_has_hashed_dentries(struct inode *inode)
        struct dentry *dentry;
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
                if (!d_unhashed(dentry) || IS_ROOT(dentry)) {
+                       spin_unlock(&dcache_inode_lock);
                        spin_unlock(&dcache_lock);
                        return true;
                }
        }
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
        return false;
 }
index a661247..de38680 100644 (file)
@@ -37,6 +37,8 @@
 
 /*
  * Usage:
+ * dcache_inode_lock protects:
+ *   - i_dentry, d_alias, d_inode
  * dcache_hash_lock protects:
  *   - the dcache hash table, s_anon lists
  * dcache_lru_lock protects:
  *   - d_unhashed()
  *   - d_parent and d_subdirs
  *   - childrens' d_child and d_parent
+ *   - d_alias, d_inode
  *
  * Ordering:
  * dcache_lock
- *   dentry->d_lock
- *     dcache_lru_lock
- *     dcache_hash_lock
+ *   dcache_inode_lock
+ *     dentry->d_lock
+ *       dcache_lru_lock
+ *       dcache_hash_lock
  *
  * If there is an ancestor relationship:
  * dentry->d_parent->...->d_parent->d_lock
 int sysctl_vfs_cache_pressure __read_mostly = 100;
 EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
 
+__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_inode_lock);
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock);
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
 __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock);
 __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
 
+EXPORT_SYMBOL(dcache_inode_lock);
 EXPORT_SYMBOL(dcache_lock);
 
 static struct kmem_cache *dentry_cache __read_mostly;
@@ -154,6 +160,7 @@ static void d_free(struct dentry *dentry)
  */
 static void dentry_iput(struct dentry * dentry)
        __releases(dentry->d_lock)
+       __releases(dcache_inode_lock)
        __releases(dcache_lock)
 {
        struct inode *inode = dentry->d_inode;
@@ -161,6 +168,7 @@ static void dentry_iput(struct dentry * dentry)
                dentry->d_inode = NULL;
                list_del_init(&dentry->d_alias);
                spin_unlock(&dentry->d_lock);
+               spin_unlock(&dcache_inode_lock);
                spin_unlock(&dcache_lock);
                if (!inode->i_nlink)
                        fsnotify_inoderemove(inode);
@@ -170,6 +178,7 @@ static void dentry_iput(struct dentry * dentry)
                        iput(inode);
        } else {
                spin_unlock(&dentry->d_lock);
+               spin_unlock(&dcache_inode_lock);
                spin_unlock(&dcache_lock);
        }
 }
@@ -231,6 +240,7 @@ static void dentry_lru_move_tail(struct dentry *dentry)
 static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
        __releases(dentry->d_lock)
        __releases(parent->d_lock)
+       __releases(dcache_inode_lock)
        __releases(dcache_lock)
 {
        list_del(&dentry->d_u.d_child);
@@ -332,13 +342,18 @@ repeat:
                         * want to reduce dcache_lock anyway so this will
                         * get improved.
                         */
+drop1:
                        spin_unlock(&dentry->d_lock);
                        goto repeat;
                }
-               if (parent && !spin_trylock(&parent->d_lock)) {
-                       spin_unlock(&dentry->d_lock);
+               if (!spin_trylock(&dcache_inode_lock)) {
+drop2:
                        spin_unlock(&dcache_lock);
-                       goto repeat;
+                       goto drop1;
+               }
+               if (parent && !spin_trylock(&parent->d_lock)) {
+                       spin_unlock(&dcache_inode_lock);
+                       goto drop2;
                }
        }
        dentry->d_count--;
@@ -369,6 +384,7 @@ repeat:
        spin_unlock(&dentry->d_lock);
        if (parent)
                spin_unlock(&parent->d_lock);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
        return;
 
@@ -558,7 +574,9 @@ struct dentry *d_find_alias(struct inode *inode)
 
        if (!list_empty(&inode->i_dentry)) {
                spin_lock(&dcache_lock);
+               spin_lock(&dcache_inode_lock);
                de = __d_find_alias(inode, 0);
+               spin_unlock(&dcache_inode_lock);
                spin_unlock(&dcache_lock);
        }
        return de;
@@ -574,18 +592,21 @@ void d_prune_aliases(struct inode *inode)
        struct dentry *dentry;
 restart:
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
                spin_lock(&dentry->d_lock);
                if (!dentry->d_count) {
                        __dget_locked_dlock(dentry);
                        __d_drop(dentry);
                        spin_unlock(&dentry->d_lock);
+                       spin_unlock(&dcache_inode_lock);
                        spin_unlock(&dcache_lock);
                        dput(dentry);
                        goto restart;
                }
                spin_unlock(&dentry->d_lock);
        }
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 }
 EXPORT_SYMBOL(d_prune_aliases);
@@ -601,6 +622,7 @@ EXPORT_SYMBOL(d_prune_aliases);
 static void prune_one_dentry(struct dentry *dentry, struct dentry *parent)
        __releases(dentry->d_lock)
        __releases(parent->d_lock)
+       __releases(dcache_inode_lock)
        __releases(dcache_lock)
 {
        __d_drop(dentry);
@@ -612,6 +634,7 @@ static void prune_one_dentry(struct dentry *dentry, struct dentry *parent)
         */
        while (dentry) {
                spin_lock(&dcache_lock);
+               spin_lock(&dcache_inode_lock);
 again:
                spin_lock(&dentry->d_lock);
                if (IS_ROOT(dentry))
@@ -627,6 +650,7 @@ again:
                        if (parent)
                                spin_unlock(&parent->d_lock);
                        spin_unlock(&dentry->d_lock);
+                       spin_unlock(&dcache_inode_lock);
                        spin_unlock(&dcache_lock);
                        return;
                }
@@ -676,8 +700,9 @@ relock:
                spin_unlock(&dcache_lru_lock);
 
                prune_one_dentry(dentry, parent);
-               /* dcache_lock and dentry->d_lock dropped */
+               /* dcache_lock, dcache_inode_lock and dentry->d_lock dropped */
                spin_lock(&dcache_lock);
+               spin_lock(&dcache_inode_lock);
                spin_lock(&dcache_lru_lock);
        }
 }
@@ -699,6 +724,7 @@ static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags)
        int cnt = *count;
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
 relock:
        spin_lock(&dcache_lru_lock);
        while (!list_empty(&sb->s_dentry_lru)) {
@@ -737,8 +763,8 @@ relock:
        if (!list_empty(&referenced))
                list_splice(&referenced, &sb->s_dentry_lru);
        spin_unlock(&dcache_lru_lock);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
-
 }
 
 /**
@@ -832,12 +858,14 @@ void shrink_dcache_sb(struct super_block *sb)
        LIST_HEAD(tmp);
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        spin_lock(&dcache_lru_lock);
        while (!list_empty(&sb->s_dentry_lru)) {
                list_splice_init(&sb->s_dentry_lru, &tmp);
                shrink_dentry_list(&tmp);
        }
        spin_unlock(&dcache_lru_lock);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 }
 EXPORT_SYMBOL(shrink_dcache_sb);
@@ -1255,9 +1283,11 @@ EXPORT_SYMBOL(d_alloc_name);
 /* the caller must hold dcache_lock */
 static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 {
+       spin_lock(&dentry->d_lock);
        if (inode)
                list_add(&dentry->d_alias, &inode->i_dentry);
        dentry->d_inode = inode;
+       spin_unlock(&dentry->d_lock);
        fsnotify_d_instantiate(dentry, inode);
 }
 
@@ -1280,7 +1310,9 @@ void d_instantiate(struct dentry *entry, struct inode * inode)
 {
        BUG_ON(!list_empty(&entry->d_alias));
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        __d_instantiate(entry, inode);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
        security_d_instantiate(entry, inode);
 }
@@ -1341,7 +1373,9 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
        BUG_ON(!list_empty(&entry->d_alias));
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        result = __d_instantiate_unique(entry, inode);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 
        if (!result) {
@@ -1432,8 +1466,10 @@ struct dentry *d_obtain_alias(struct inode *inode)
        tmp->d_parent = tmp; /* make sure dput doesn't croak */
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        res = __d_find_alias(inode, 0);
        if (res) {
+               spin_unlock(&dcache_inode_lock);
                spin_unlock(&dcache_lock);
                dput(tmp);
                goto out_iput;
@@ -1450,6 +1486,7 @@ struct dentry *d_obtain_alias(struct inode *inode)
        hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon);
        spin_unlock(&dcache_hash_lock);
        spin_unlock(&tmp->d_lock);
+       spin_unlock(&dcache_inode_lock);
 
        spin_unlock(&dcache_lock);
        return tmp;
@@ -1482,9 +1519,11 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
 
        if (inode && S_ISDIR(inode->i_mode)) {
                spin_lock(&dcache_lock);
+               spin_lock(&dcache_inode_lock);
                new = __d_find_alias(inode, 1);
                if (new) {
                        BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
+                       spin_unlock(&dcache_inode_lock);
                        spin_unlock(&dcache_lock);
                        security_d_instantiate(new, inode);
                        d_move(new, dentry);
@@ -1492,6 +1531,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
                } else {
                        /* already taking dcache_lock, so d_add() by hand */
                        __d_instantiate(dentry, inode);
+                       spin_unlock(&dcache_inode_lock);
                        spin_unlock(&dcache_lock);
                        security_d_instantiate(dentry, inode);
                        d_rehash(dentry);
@@ -1566,8 +1606,10 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
         * already has a dentry.
         */
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) {
                __d_instantiate(found, inode);
+               spin_unlock(&dcache_inode_lock);
                spin_unlock(&dcache_lock);
                security_d_instantiate(found, inode);
                return found;
@@ -1579,6 +1621,7 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
         */
        new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
        dget_locked(new);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
        security_d_instantiate(found, inode);
        d_move(new, found);
@@ -1797,6 +1840,7 @@ void d_delete(struct dentry * dentry)
         * Are we the only user?
         */
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        spin_lock(&dentry->d_lock);
        isdir = S_ISDIR(dentry->d_inode->i_mode);
        if (dentry->d_count == 1) {
@@ -1810,6 +1854,7 @@ void d_delete(struct dentry * dentry)
                __d_drop(dentry);
 
        spin_unlock(&dentry->d_lock);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 
        fsnotify_nameremove(dentry, isdir);
@@ -2067,6 +2112,7 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
  */
 static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
        __releases(dcache_lock)
+       __releases(dcache_inode_lock)
 {
        struct mutex *m1 = NULL, *m2 = NULL;
        struct dentry *ret;
@@ -2092,6 +2138,7 @@ out_unalias:
        d_move_locked(alias, dentry);
        ret = alias;
 out_err:
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
        if (m2)
                mutex_unlock(m2);
@@ -2153,6 +2200,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
        BUG_ON(!d_unhashed(dentry));
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
 
        if (!inode) {
                actual = dentry;
@@ -2196,6 +2244,7 @@ found:
        _d_rehash(actual);
        spin_unlock(&dcache_hash_lock);
        spin_unlock(&actual->d_lock);
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 out_nolock:
        if (actual == dentry) {
@@ -2207,6 +2256,7 @@ out_nolock:
        return actual;
 
 shouldnt_be_hashed:
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
        BUG();
 }
index 51b3040..84b8c46 100644 (file)
@@ -48,8 +48,10 @@ find_acceptable_alias(struct dentry *result,
                return result;
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
                dget_locked(dentry);
+               spin_unlock(&dcache_inode_lock);
                spin_unlock(&dcache_lock);
                if (toput)
                        dput(toput);
@@ -58,8 +60,10 @@ find_acceptable_alias(struct dentry *result,
                        return dentry;
                }
                spin_lock(&dcache_lock);
+               spin_lock(&dcache_inode_lock);
                toput = dentry;
        }
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 
        if (toput)
index ac7b814..850f67d 100644 (file)
@@ -64,7 +64,11 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i
                 * Oops, since the test for IS_ROOT() will fail.
                 */
                spin_lock(&dcache_lock);
+               spin_lock(&dcache_inode_lock);
+               spin_lock(&sb->s_root->d_lock);
                list_del_init(&sb->s_root->d_alias);
+               spin_unlock(&sb->s_root->d_lock);
+               spin_unlock(&dcache_inode_lock);
                spin_unlock(&dcache_lock);
        }
        return 0;
index aa4f25e..ae769fc 100644 (file)
@@ -60,6 +60,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
        watched = fsnotify_inode_watches_children(inode);
 
        spin_lock(&dcache_lock);
+       spin_lock(&dcache_inode_lock);
        /* run all of the dentries associated with this inode.  Since this is a
         * directory, there damn well better only be one item on this list */
        list_for_each_entry(alias, &inode->i_dentry, d_alias) {
@@ -82,6 +83,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
                }
                spin_unlock(&alias->d_lock);
        }
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 }
 
index 35e5f5a..c31b5c6 100644 (file)
@@ -170,7 +170,7 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode,
        struct dentry *dentry = NULL;
 
        spin_lock(&dcache_lock);
-
+       spin_lock(&dcache_inode_lock);
        list_for_each(p, &inode->i_dentry) {
                dentry = list_entry(p, struct dentry, d_alias);
 
@@ -188,6 +188,7 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode,
                dentry = NULL;
        }
 
+       spin_unlock(&dcache_inode_lock);
        spin_unlock(&dcache_lock);
 
        return dentry;
index ddf4f55..bda5ec0 100644 (file)
@@ -181,6 +181,7 @@ struct dentry_operations {
 
 #define DCACHE_CANT_MOUNT      0x0100
 
+extern spinlock_t dcache_inode_lock;
 extern spinlock_t dcache_lock;
 extern seqlock_t rename_lock;