From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 42c326082d8a2c91506f951ace638deae1faf083 upstream.
we have too many iterators in fs/dcache.c...
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
fs/dcache.c | 195 ++++++++++++++++++++++++++----------------------------------
1 file changed, 85 insertions(+), 110 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 87b70fe7eccc..6a9731129ae9 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1073,116 +1073,6 @@ void shrink_dcache_sb(struct super_block *sb)
EXPORT_SYMBOL(shrink_dcache_sb);
/*
- * destroy a single subtree of dentries for unmount
- * - see the comments on shrink_dcache_for_umount() for a description of the
- * locking
- */
-static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
-{
- struct dentry *parent;
-
- BUG_ON(!IS_ROOT(dentry));
-
- for (;;) {
- /* descend to the first leaf in the current subtree */
- while (!list_empty(&dentry->d_subdirs))
- dentry = list_entry(dentry->d_subdirs.next,
- struct dentry, d_u.d_child);
-
- /* consume the dentries from this leaf up through its parents
- * until we find one with children or run out altogether */
- do {
- struct inode *inode;
-
- /*
- * inform the fs that this dentry is about to be
- * unhashed and destroyed.
- */
- if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
- !d_unhashed(dentry))
- dentry->d_op->d_prune(dentry);
-
- dentry_lru_del(dentry);
- __d_shrink(dentry);
-
- if (dentry->d_lockref.count != 0) {
- printk(KERN_ERR
- "BUG: Dentry %p{i=%lx,n=%s}"
- " still in use (%d)"
- " [unmount of %s %s]\n",
- dentry,
- dentry->d_inode ?
- dentry->d_inode->i_ino : 0UL,
- dentry->d_name.name,
- dentry->d_lockref.count,
- dentry->d_sb->s_type->name,
- dentry->d_sb->s_id);
- BUG();
- }
-
- if (IS_ROOT(dentry)) {
- parent = NULL;
- list_del(&dentry->d_u.d_child);
- } else {
- parent = dentry->d_parent;
- parent->d_lockref.count--;
- list_del(&dentry->d_u.d_child);
- }
-
- inode = dentry->d_inode;
- if (inode) {
- dentry->d_inode = NULL;
- hlist_del_init(&dentry->d_alias);
- if (dentry->d_op && dentry->d_op->d_iput)
- dentry->d_op->d_iput(dentry, inode);
- else
- iput(inode);
- }
-
- d_free(dentry);
-
- /* finished when we fall off the top of the tree,
- * otherwise we ascend to the parent and move to the
- * next sibling if there is one */
- if (!parent)
- return;
- dentry = parent;
- } while (list_empty(&dentry->d_subdirs));
-
- dentry = list_entry(dentry->d_subdirs.next,
- struct dentry, d_u.d_child);
- }
-}
-
-/*
- * destroy the dentries attached to a superblock on unmounting
- * - we don't need to use dentry->d_lock because:
- * - the superblock is detached from all mountings and open files, so the
- * dentry trees will not be rearranged by the VFS
- * - s_umount is write-locked, so the memory pressure shrinker will ignore
- * any dentries belonging to this superblock that it comes across
- * - the filesystem itself is no longer permitted to rearrange the dentries
- * in this superblock
- */
-void shrink_dcache_for_umount(struct super_block *sb)
-{
- struct dentry *dentry;
-
- if (down_read_trylock(&sb->s_umount))
- BUG();
-
- dentry = sb->s_root;
- sb->s_root = NULL;
- dentry->d_lockref.count--;
- shrink_dcache_for_umount_subtree(dentry);
-
- while (!hlist_bl_empty(&sb->s_anon)) {
- dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
- shrink_dcache_for_umount_subtree(dentry);
- }
-}
-
-/*
* This tries to ascend one level of parenthood, but
* we can race with renaming, so we need to re-check
* the parenthood after dropping the lock and check
@@ -1475,6 +1365,91 @@ void shrink_dcache_parent(struct dentry *parent)
}
EXPORT_SYMBOL(shrink_dcache_parent);
+static enum d_walk_ret umount_collect(void *_data, struct dentry *dentry)
+{
+ struct select_data *data = _data;
+ enum d_walk_ret ret = D_WALK_CONTINUE;
+
+ if (dentry->d_lockref.count) {
+ dentry_lru_del(dentry);
+ if (likely(!list_empty(&dentry->d_subdirs)))
+ goto out;
+ if (dentry == data->start && dentry->d_lockref.count == 1)
+ goto out;
+ printk(KERN_ERR
+ "BUG: Dentry %p{i=%lx,n=%s}"
+ " still in use (%d)"
+ " [unmount of %s %s]\n",
+ dentry,
+ dentry->d_inode ?
+ dentry->d_inode->i_ino : 0UL,
+ dentry->d_name.name,
+ dentry->d_lockref.count,
+ dentry->d_sb->s_type->name,
+ dentry->d_sb->s_id);
+ BUG();
+ } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
+ /*
+ * We can't use d_lru_shrink_move() because we
+ * need to get the global LRU lock and do the
+ * LRU accounting.
+ */
+ if (dentry->d_flags & DCACHE_LRU_LIST)
+ d_lru_del(dentry);
+ d_shrink_add(dentry, &data->dispose);
+ data->found++;
+ ret = D_WALK_NORETRY;
+ }
+out:
+ if (data->found && need_resched())
+ ret = D_WALK_QUIT;
+ return ret;
+}
+
+/*
+ * destroy the dentries attached to a superblock on unmounting
+ */
+void shrink_dcache_for_umount(struct super_block *sb)
+{
+ struct dentry *dentry;
+
+ if (down_read_trylock(&sb->s_umount))
+ BUG();
+
+ dentry = sb->s_root;
+ sb->s_root = NULL;
+ for (;;) {
+ struct select_data data;
+
+ INIT_LIST_HEAD(&data.dispose);
+ data.start = dentry;
+ data.found = 0;
+
+ d_walk(dentry, &data, umount_collect, NULL);
+ if (!data.found)
+ break;
+
+ shrink_dentry_list(&data.dispose);
+ cond_resched();
+ }
+ d_drop(dentry);
+ dput(dentry);
+
+ while (!hlist_bl_empty(&sb->s_anon)) {
+ struct select_data data;
+ dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
+
+ INIT_LIST_HEAD(&data.dispose);
+ data.start = NULL;
+ data.found = 0;
+
+ d_walk(dentry, &data, umount_collect, NULL);
+ if (data.found)
+ shrink_dentry_list(&data.dispose);
+ cond_resched();
+ }
+}
+
static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry)
{
struct select_data *data = _data;
--
2.1.2
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