dcache: don't need rcu in shrink_dentry_list()

Since now the shrink list is private and nobody can free the dentry while
it is on the shrink list, we can remove RCU protection from this.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 23 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 2321e1a861f6..42ae01eefc07 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -796,23 +796,9 @@ static void shrink_dentry_list(struct list_head *list)
 {
         struct dentry *dentry, *parent;
 
-        rcu_read_lock();
-        for (;;) {
-                dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
-                if (&dentry->d_lru == list)
-                        break; /* empty */
-
-                /*
-                 * Get the dentry lock, and re-verify that the dentry is
-                 * this on the shrinking list. If it is, we know that
-                 * DCACHE_SHRINK_LIST and DCACHE_LRU_LIST are set.
-                 */
+        while (!list_empty(list)) {
+                dentry = list_entry(list->prev, struct dentry, d_lru);
                 spin_lock(&dentry->d_lock);
-                if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
-                        spin_unlock(&dentry->d_lock);
-                        continue;
-                }
-
                 /*
                  * The dispose list is isolated and dentries are not accounted
                  * to the LRU here, so we can simply remove it from the list
@@ -828,23 +814,20 @@ static void shrink_dentry_list(struct list_head *list)
                         spin_unlock(&dentry->d_lock);
                         continue;
                 }
-                rcu_read_unlock();
 
                 parent = dentry_kill(dentry, 0);
                 /*
                  * If dentry_kill returns NULL, we have nothing more to do.
                  */
-                if (!parent) {
-                        rcu_read_lock();
+                if (!parent)
                         continue;
-                }
+
                 if (unlikely(parent == dentry)) {
                         /*
                          * trylocks have failed and d_lock has been held the
                          * whole time, so it could not have been added to any
                          * other lists. Just add it back to the shrink list.
                          */
-                        rcu_read_lock();
                         d_shrink_add(dentry, list);
                         spin_unlock(&dentry->d_lock);
                         continue;
@@ -858,9 +841,7 @@ static void shrink_dentry_list(struct list_head *list)
                 dentry = parent;
                 while (dentry && !lockref_put_or_lock(&dentry->d_lockref))
                         dentry = dentry_kill(dentry, 1);
-                rcu_read_lock();
         }
-        rcu_read_unlock();
 }
 
 static enum lru_status