expand dentry_kill(dentry, 0) in shrink_dentry_list()

Result will be massaged to saner shape in the next commits.  It is
ugly, no questions - the point of that one is to be a provably
equivalent transformation (and it might be worth splitting a bit
more).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 17 insertions, 13 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 1577c14dfb4e..c23f78a9d156 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -801,6 +801,7 @@ static void shrink_dentry_list(struct list_head *list)
         struct dentry *dentry, *parent;
 
         while (!list_empty(list)) {
+                struct inode *inode;
                 dentry = list_entry(list->prev, struct dentry, d_lru);
                 spin_lock(&dentry->d_lock);
                 /*
@@ -828,23 +829,26 @@ static void shrink_dentry_list(struct list_head *list)
                         continue;
                 }
 
-                parent = dentry_kill(dentry, 0);
-                /*
-                 * If dentry_kill returns NULL, we have nothing more to do.
-                 */
-                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.
-                         */
+                inode = dentry->d_inode;
+                if (inode && unlikely(!spin_trylock(&inode->i_lock))) {
                         d_shrink_add(dentry, list);
                         spin_unlock(&dentry->d_lock);
                         continue;
                 }
+
+                parent = NULL;
+                if (!IS_ROOT(dentry)) {
+                        parent = dentry->d_parent;
+                        if (unlikely(!spin_trylock(&parent->d_lock))) {
+                                if (inode)
+                                        spin_unlock(&inode->i_lock);
+                                d_shrink_add(dentry, list);
+                                spin_unlock(&dentry->d_lock);
+                                continue;
+                        }
+                }
+
+                __dentry_kill(dentry);
                 /*
                  * We need to prune ancestors too. This is necessary to prevent
                  * quadratic behavior of shrink_dcache_parent(), but is also