expand dentry_kill(dentry, 0) in shrink_dentry_list()

commit ff2fde9929feb2aef45377ce56b8b12df85dda69 upstream.

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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/fs/dcache.c b/fs/dcache.c
index 7575aeec17408c311a8199095da0eb11a9aeb716..d66649a44f75bba931d9445ed7db4cb7ebb1af5c 100644 (file)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -823,6 +823,7 @@ 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);
                /*
@@ -850,23 +851,26 @@ 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