fs: dcache rationalise dget variants

dget_locked was a shortcut to avoid the lazy lru manipulation when we already
held dcache_lock (lru manipulation was relatively cheap at that point).
However, how that the lru lock is an innermost one, we never hold it at any
caller, so the lock cost can now be avoided. We already have well working lazy
dcache LRU, so it should be fine to defer LRU manipulations to scan time.

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

5 files changed, 15 insertions, 29 deletions

diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c
index fb3a55f..c83f476 100644
--- a/fs/configfs/inode.c
+++ b/fs/configfs/inode.c
@@ -252,7 +252,7 @@ void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 	if (dentry) {
 		spin_lock(&dentry->d_lock);
 		if (!(d_unhashed(dentry) && dentry->d_inode)) {
-			dget_locked_dlock(dentry);
+			dget_dlock(dentry);
 			__d_drop(dentry);
 			spin_unlock(&dentry->d_lock);
 			simple_unlink(parent->d_inode, dentry);
diff --git a/fs/dcache.c b/fs/dcache.c
index 01f0167..b4d2e28 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -429,32 +429,17 @@ int d_invalidate(struct dentry * dentry)
 EXPORT_SYMBOL(d_invalidate);
 
 /* This must be called with d_lock held */
-static inline struct dentry * __dget_locked_dlock(struct dentry *dentry)
+static inline void __dget_dlock(struct dentry *dentry)
 {
 	dentry->d_count++;
-	dentry_lru_del(dentry);
-	return dentry;
 }
 
-/* This must be called with d_lock held */
-static inline struct dentry * __dget_locked(struct dentry *dentry)
+static inline void __dget(struct dentry *dentry)
 {
 	spin_lock(&dentry->d_lock);
-	__dget_locked_dlock(dentry);
+	__dget_dlock(dentry);
 	spin_unlock(&dentry->d_lock);
-	return dentry;
-}
-
-struct dentry * dget_locked_dlock(struct dentry *dentry)
-{
-	return __dget_locked_dlock(dentry);
-}
-
-struct dentry * dget_locked(struct dentry *dentry)
-{
-	return __dget_locked(dentry);
 }
-EXPORT_SYMBOL(dget_locked);
 
 struct dentry *dget_parent(struct dentry *dentry)
 {
@@ -512,7 +497,7 @@ again:
 			    (alias->d_flags & DCACHE_DISCONNECTED)) {
 				discon_alias = alias;
 			} else if (!want_discon) {
-				__dget_locked_dlock(alias);
+				__dget_dlock(alias);
 				spin_unlock(&alias->d_lock);
 				return alias;
 			}
@@ -525,7 +510,7 @@ again:
 		if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
 			if (IS_ROOT(alias) &&
 			    (alias->d_flags & DCACHE_DISCONNECTED)) {
-				__dget_locked_dlock(alias);
+				__dget_dlock(alias);
 				spin_unlock(&alias->d_lock);
 				return alias;
 			}
@@ -561,7 +546,7 @@ restart:
 	list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
 		spin_lock(&dentry->d_lock);
 		if (!dentry->d_count) {
-			__dget_locked_dlock(dentry);
+			__dget_dlock(dentry);
 			__d_drop(dentry);
 			spin_unlock(&dentry->d_lock);
 			spin_unlock(&dcache_inode_lock);
@@ -1257,7 +1242,8 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
 		 * don't need child lock because it is not subject
 		 * to concurrency here
 		 */
-		dentry->d_parent = dget_dlock(parent);
+		__dget_dlock(parent);
+		dentry->d_parent = parent;
 		dentry->d_sb = parent->d_sb;
 		list_add(&dentry->d_u.d_child, &parent->d_subdirs);
 		spin_unlock(&parent->d_lock);
@@ -1360,7 +1346,7 @@ static struct dentry *__d_instantiate_unique(struct dentry *entry,
 			continue;
 		if (memcmp(qstr->name, name, len))
 			continue;
-		dget_locked(alias);
+		__dget(alias);
 		return alias;
 	}
 
@@ -1613,7 +1599,7 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
 	 * reference to it, move it in place and use it.
 	 */
 	new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
-	dget_locked(new);
+	__dget(new);
 	spin_unlock(&dcache_inode_lock);
 	security_d_instantiate(found, inode);
 	d_move(new, found);
@@ -1789,7 +1775,7 @@ int d_validate(struct dentry *dentry, struct dentry *dparent)
 	list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
 		if (dentry == child) {
 			spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
-			__dget_locked_dlock(dentry);
+			__dget_dlock(dentry);
 			spin_unlock(&dentry->d_lock);
 			spin_unlock(&dparent->d_lock);
 			return 1;
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 53a5c08..f06a940 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -49,7 +49,7 @@ find_acceptable_alias(struct dentry *result,
 
 	spin_lock(&dcache_inode_lock);
 	list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
-		dget_locked(dentry);
+		dget(dentry);
 		spin_unlock(&dcache_inode_lock);
 		if (toput)
 			dput(toput);
diff --git a/fs/ncpfs/dir.c b/fs/ncpfs/dir.c
index de15c53..0ba3cdc 100644
--- a/fs/ncpfs/dir.c
+++ b/fs/ncpfs/dir.c
@@ -397,7 +397,7 @@ ncp_dget_fpos(struct dentry *dentry, struct dentry *parent, unsigned long fpos)
 		dent = list_entry(next, struct dentry, d_u.d_child);
 		if ((unsigned long)dent->d_fsdata == fpos) {
 			if (dent->d_inode)
-				dget_locked(dent);
+				dget(dent);
 			else
 				dent = NULL;
 			spin_unlock(&parent->d_lock);
diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c
index b7de749..4d54c60 100644
--- a/fs/ocfs2/dcache.c
+++ b/fs/ocfs2/dcache.c
@@ -178,7 +178,7 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode,
 			mlog(0, "dentry found: %.*s\n",
 			     dentry->d_name.len, dentry->d_name.name);
 
-			dget_locked_dlock(dentry);
+			dget_dlock(dentry);
 			spin_unlock(&dentry->d_lock);
 			break;
 		}