fs: dcache per-inode inode alias locking
Nick Piggin [Fri, 7 Jan 2011 06:50:06 +0000 (17:50 +1100)]
dcache_inode_lock can be replaced with per-inode locking. Use existing
inode->i_lock for this. This is slightly non-trivial because we sometimes
need to find the inode from the dentry, which requires d_inode to be
stabilised (either with refcount or 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 df8bbb3..5978298 100644 (file)
@@ -277,11 +277,11 @@ static struct dentry *v9fs_dentry_from_dir_inode(struct inode *inode)
 {
        struct dentry *dentry;
 
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_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(&inode->i_lock);
        return dentry;
 }
 
index 600101a..3a4557e 100644 (file)
@@ -128,7 +128,7 @@ affs_fix_dcache(struct dentry *dentry, u32 entry_ino)
        void *data = dentry->d_fsdata;
        struct list_head *head, *next;
 
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_lock);
        head = &inode->i_dentry;
        next = head->next;
        while (next != head) {
@@ -139,7 +139,7 @@ affs_fix_dcache(struct dentry *dentry, u32 entry_ino)
                }
                next = next->next;
        }
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
 }
 
 
index 2a239d8..a853a89 100644 (file)
@@ -809,14 +809,14 @@ inode_has_hashed_dentries(struct inode *inode)
 {
        struct dentry *dentry;
 
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_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(&inode->i_lock);
                        return true;
                }
        }
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
        return false;
 }
 
index 9f04e1b..09ec945 100644 (file)
@@ -39,8 +39,8 @@
 
 /*
  * Usage:
- * dcache_inode_lock protects:
- *   - i_dentry, d_alias, d_inode
+ * dcache->d_inode->i_lock protects:
+ *   - i_dentry, d_alias, d_inode of aliases
  * dcache_hash_bucket lock protects:
  *   - the dcache hash table
  * s_anon bl list spinlock protects:
@@ -58,7 +58,7 @@
  *   - d_alias, d_inode
  *
  * Ordering:
- * dcache_inode_lock
+ * dentry->d_inode->i_lock
  *   dentry->d_lock
  *     dcache_lru_lock
  *     dcache_hash_bucket 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_lru_lock);
 __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
 
 EXPORT_SYMBOL(rename_lock);
-EXPORT_SYMBOL(dcache_inode_lock);
 
 static struct kmem_cache *dentry_cache __read_mostly;
 
@@ -196,14 +194,14 @@ static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
  */
 static void dentry_iput(struct dentry * dentry)
        __releases(dentry->d_lock)
-       __releases(dcache_inode_lock)
+       __releases(dentry->d_inode->i_lock)
 {
        struct inode *inode = dentry->d_inode;
        if (inode) {
                dentry->d_inode = NULL;
                list_del_init(&dentry->d_alias);
                spin_unlock(&dentry->d_lock);
-               spin_unlock(&dcache_inode_lock);
+               spin_unlock(&inode->i_lock);
                if (!inode->i_nlink)
                        fsnotify_inoderemove(inode);
                if (dentry->d_op && dentry->d_op->d_iput)
@@ -212,7 +210,6 @@ static void dentry_iput(struct dentry * dentry)
                        iput(inode);
        } else {
                spin_unlock(&dentry->d_lock);
-               spin_unlock(&dcache_inode_lock);
        }
 }
 
@@ -222,14 +219,14 @@ static void dentry_iput(struct dentry * dentry)
  */
 static void dentry_unlink_inode(struct dentry * dentry)
        __releases(dentry->d_lock)
-       __releases(dcache_inode_lock)
+       __releases(dentry->d_inode->i_lock)
 {
        struct inode *inode = dentry->d_inode;
        dentry->d_inode = NULL;
        list_del_init(&dentry->d_alias);
        dentry_rcuwalk_barrier(dentry);
        spin_unlock(&dentry->d_lock);
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
        if (!inode->i_nlink)
                fsnotify_inoderemove(inode);
        if (dentry->d_op && dentry->d_op->d_iput)
@@ -295,7 +292,7 @@ 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(dentry->d_inode->i_lock)
 {
        dentry->d_parent = NULL;
        list_del(&dentry->d_u.d_child);
@@ -370,9 +367,11 @@ EXPORT_SYMBOL(d_drop);
 static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
        __releases(dentry->d_lock)
 {
+       struct inode *inode;
        struct dentry *parent;
 
-       if (!spin_trylock(&dcache_inode_lock)) {
+       inode = dentry->d_inode;
+       if (inode && !spin_trylock(&inode->i_lock)) {
 relock:
                spin_unlock(&dentry->d_lock);
                cpu_relax();
@@ -383,7 +382,8 @@ relock:
        else
                parent = dentry->d_parent;
        if (parent && !spin_trylock(&parent->d_lock)) {
-               spin_unlock(&dcache_inode_lock);
+               if (inode)
+                       spin_unlock(&inode->i_lock);
                goto relock;
        }
 
@@ -618,9 +618,9 @@ struct dentry *d_find_alias(struct inode *inode)
        struct dentry *de = NULL;
 
        if (!list_empty(&inode->i_dentry)) {
-               spin_lock(&dcache_inode_lock);
+               spin_lock(&inode->i_lock);
                de = __d_find_alias(inode, 0);
-               spin_unlock(&dcache_inode_lock);
+               spin_unlock(&inode->i_lock);
        }
        return de;
 }
@@ -634,20 +634,20 @@ void d_prune_aliases(struct inode *inode)
 {
        struct dentry *dentry;
 restart:
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_lock);
        list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
                spin_lock(&dentry->d_lock);
                if (!dentry->d_count) {
                        __dget_dlock(dentry);
                        __d_drop(dentry);
                        spin_unlock(&dentry->d_lock);
-                       spin_unlock(&dcache_inode_lock);
+                       spin_unlock(&inode->i_lock);
                        dput(dentry);
                        goto restart;
                }
                spin_unlock(&dentry->d_lock);
        }
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
 }
 EXPORT_SYMBOL(d_prune_aliases);
 
@@ -1392,9 +1392,11 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 void d_instantiate(struct dentry *entry, struct inode * inode)
 {
        BUG_ON(!list_empty(&entry->d_alias));
-       spin_lock(&dcache_inode_lock);
+       if (inode)
+               spin_lock(&inode->i_lock);
        __d_instantiate(entry, inode);
-       spin_unlock(&dcache_inode_lock);
+       if (inode)
+               spin_unlock(&inode->i_lock);
        security_d_instantiate(entry, inode);
 }
 EXPORT_SYMBOL(d_instantiate);
@@ -1458,9 +1460,11 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
 
        BUG_ON(!list_empty(&entry->d_alias));
 
-       spin_lock(&dcache_inode_lock);
+       if (inode)
+               spin_lock(&inode->i_lock);
        result = __d_instantiate_unique(entry, inode);
-       spin_unlock(&dcache_inode_lock);
+       if (inode)
+               spin_unlock(&inode->i_lock);
 
        if (!result) {
                security_d_instantiate(entry, inode);
@@ -1542,10 +1546,10 @@ struct dentry *d_obtain_alias(struct inode *inode)
        tmp->d_parent = tmp; /* make sure dput doesn't croak */
 
 
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_lock);
        res = __d_find_alias(inode, 0);
        if (res) {
-               spin_unlock(&dcache_inode_lock);
+               spin_unlock(&inode->i_lock);
                dput(tmp);
                goto out_iput;
        }
@@ -1561,7 +1565,7 @@ struct dentry *d_obtain_alias(struct inode *inode)
        hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
        __bit_spin_unlock(0, (unsigned long *)&tmp->d_sb->s_anon.first);
        spin_unlock(&tmp->d_lock);
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
 
        return tmp;
 
@@ -1592,18 +1596,18 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
        struct dentry *new = NULL;
 
        if (inode && S_ISDIR(inode->i_mode)) {
-               spin_lock(&dcache_inode_lock);
+               spin_lock(&inode->i_lock);
                new = __d_find_alias(inode, 1);
                if (new) {
                        BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
-                       spin_unlock(&dcache_inode_lock);
+                       spin_unlock(&inode->i_lock);
                        security_d_instantiate(new, inode);
                        d_move(new, dentry);
                        iput(inode);
                } else {
-                       /* already got dcache_inode_lock, so d_add() by hand */
+                       /* already taking inode->i_lock, so d_add() by hand */
                        __d_instantiate(dentry, inode);
-                       spin_unlock(&dcache_inode_lock);
+                       spin_unlock(&inode->i_lock);
                        security_d_instantiate(dentry, inode);
                        d_rehash(dentry);
                }
@@ -1676,10 +1680,10 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
         * Negative dentry: instantiate it unless the inode is a directory and
         * already has a dentry.
         */
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_lock);
        if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) {
                __d_instantiate(found, inode);
-               spin_unlock(&dcache_inode_lock);
+               spin_unlock(&inode->i_lock);
                security_d_instantiate(found, inode);
                return found;
        }
@@ -1690,7 +1694,7 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
         */
        new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
        __dget(new);
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
        security_d_instantiate(found, inode);
        d_move(new, found);
        iput(inode);
@@ -2004,15 +2008,17 @@ EXPORT_SYMBOL(d_validate);
  
 void d_delete(struct dentry * dentry)
 {
+       struct inode *inode;
        int isdir = 0;
        /*
         * Are we the only user?
         */
 again:
        spin_lock(&dentry->d_lock);
-       isdir = S_ISDIR(dentry->d_inode->i_mode);
+       inode = dentry->d_inode;
+       isdir = S_ISDIR(inode->i_mode);
        if (dentry->d_count == 1) {
-               if (!spin_trylock(&dcache_inode_lock)) {
+               if (inode && !spin_trylock(&inode->i_lock)) {
                        spin_unlock(&dentry->d_lock);
                        cpu_relax();
                        goto again;
@@ -2266,13 +2272,13 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
  * This helper attempts to cope with remotely renamed directories
  *
  * It assumes that the caller is already holding
- * dentry->d_parent->d_inode->i_mutex and the dcache_inode_lock
+ * dentry->d_parent->d_inode->i_mutex and the inode->i_lock
  *
  * Note: If ever the locking in lock_rename() changes, then please
  * remember to update this too...
  */
-static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
-       __releases(dcache_inode_lock)
+static struct dentry *__d_unalias(struct inode *inode,
+               struct dentry *dentry, struct dentry *alias)
 {
        struct mutex *m1 = NULL, *m2 = NULL;
        struct dentry *ret;
@@ -2298,7 +2304,7 @@ out_unalias:
        d_move(alias, dentry);
        ret = alias;
 out_err:
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
        if (m2)
                mutex_unlock(m2);
        if (m1)
@@ -2371,7 +2377,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
                goto out_nolock;
        }
 
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_lock);
 
        if (S_ISDIR(inode->i_mode)) {
                struct dentry *alias;
@@ -2388,7 +2394,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
                                goto found;
                        }
                        /* Nope, but we must(!) avoid directory aliasing */
-                       actual = __d_unalias(dentry, alias);
+                       actual = __d_unalias(inode, dentry, alias);
                        if (IS_ERR(actual))
                                dput(alias);
                        goto out_nolock;
@@ -2406,7 +2412,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
 found:
        _d_rehash(actual);
        spin_unlock(&actual->d_lock);
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
 out_nolock:
        if (actual == dentry) {
                security_d_instantiate(dentry, inode);
index f06a940..4b68257 100644 (file)
@@ -43,24 +43,26 @@ find_acceptable_alias(struct dentry *result,
                void *context)
 {
        struct dentry *dentry, *toput = NULL;
+       struct inode *inode;
 
        if (acceptable(context, result))
                return result;
 
-       spin_lock(&dcache_inode_lock);
-       list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
+       inode = result->d_inode;
+       spin_lock(&inode->i_lock);
+       list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
                dget(dentry);
-               spin_unlock(&dcache_inode_lock);
+               spin_unlock(&inode->i_lock);
                if (toput)
                        dput(toput);
                if (dentry != result && acceptable(context, dentry)) {
                        dput(result);
                        return dentry;
                }
-               spin_lock(&dcache_inode_lock);
+               spin_lock(&inode->i_lock);
                toput = dentry;
        }
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
 
        if (toput)
                dput(toput);
index c3a5a11..5596c6a 100644 (file)
@@ -63,11 +63,11 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i
                 * This again causes shrink_dcache_for_umount_subtree() to
                 * Oops, since the test for IS_ROOT() will fail.
                 */
-               spin_lock(&dcache_inode_lock);
+               spin_lock(&sb->s_root->d_inode->i_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(&sb->s_root->d_inode->i_lock);
        }
        return 0;
 }
index 9be6ec1..79b47cb 100644 (file)
@@ -59,7 +59,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
        /* determine if the children should tell inode about their events */
        watched = fsnotify_inode_watches_children(inode);
 
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_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) {
@@ -82,7 +82,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
                }
                spin_unlock(&alias->d_lock);
        }
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
 }
 
 /* Notify this dentry's parent about a child's events. */
index 0310b16..6d80ecc 100644 (file)
@@ -175,7 +175,7 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode,
        struct list_head *p;
        struct dentry *dentry = NULL;
 
-       spin_lock(&dcache_inode_lock);
+       spin_lock(&inode->i_lock);
        list_for_each(p, &inode->i_dentry) {
                dentry = list_entry(p, struct dentry, d_alias);
 
@@ -193,7 +193,7 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode,
                dentry = NULL;
        }
 
-       spin_unlock(&dcache_inode_lock);
+       spin_unlock(&inode->i_lock);
 
        return dentry;
 }
index 5f0392e..d719e4d 100644 (file)
@@ -191,7 +191,6 @@ struct dentry_operations {
 #define DCACHE_OP_REVALIDATE   0x4000
 #define DCACHE_OP_DELETE       0x8000
 
-extern spinlock_t dcache_inode_lock;
 extern seqlock_t rename_lock;
 
 static inline int dname_external(struct dentry *dentry)