fs: dcache reduce dcache_inode_lock

dcache_inode_lock can be avoided in d_delete() and d_materialise_unique()
in cases where it is not required.

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

1 files changed, 12 insertions, 12 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index ccdc5c2512df..01f016799fd4 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1828,10 +1828,15 @@ void d_delete(struct dentry * dentry)
         /*
          * Are we the only user?
          */
-        spin_lock(&dcache_inode_lock);
+again:
         spin_lock(&dentry->d_lock);
         isdir = S_ISDIR(dentry->d_inode->i_mode);
         if (dentry->d_count == 1) {
+                if (!spin_trylock(&dcache_inode_lock)) {
+                        spin_unlock(&dentry->d_lock);
+                        cpu_relax();
+                        goto again;
+                }
                 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
                 dentry_iput(dentry);
                 fsnotify_nameremove(dentry, isdir);
@@ -1842,7 +1847,6 @@ void d_delete(struct dentry * dentry)
                 __d_drop(dentry);
 
         spin_unlock(&dentry->d_lock);
-        spin_unlock(&dcache_inode_lock);
 
         fsnotify_nameremove(dentry, isdir);
 }
@@ -2164,14 +2168,15 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
 
         BUG_ON(!d_unhashed(dentry));
 
-        spin_lock(&dcache_inode_lock);
-
         if (!inode) {
                 actual = dentry;
                 __d_instantiate(dentry, NULL);
-                goto found_lock;
+                d_rehash(actual);
+                goto out_nolock;
         }
 
+        spin_lock(&dcache_inode_lock);
+
         if (S_ISDIR(inode->i_mode)) {
                 struct dentry *alias;
 
@@ -2198,10 +2203,9 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
         actual = __d_instantiate_unique(dentry, inode);
         if (!actual)
                 actual = dentry;
-        else if (unlikely(!d_unhashed(actual)))
-                goto shouldnt_be_hashed;
+        else
+                BUG_ON(!d_unhashed(actual));
 
-found_lock:
         spin_lock(&actual->d_lock);
 found:
         spin_lock(&dcache_hash_lock);
@@ -2217,10 +2221,6 @@ out_nolock:
 
         iput(inode);
         return actual;
-
-shouldnt_be_hashed:
-        spin_unlock(&dcache_inode_lock);
-        BUG();
 }
 EXPORT_SYMBOL_GPL(d_materialise_unique);