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authorLinus Torvalds <torvalds@linux-foundation.org>2011-03-15 15:29:21 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2011-03-23 13:03:31 -0700
commitc4e8d54f595b01d30e9b2793413d44f83deb7450 (patch)
tree90ede1626994e8d63457159df6c2718e50ba5478 /fs
parent521cb40b0c44418a4fd36dc633f575813d59a43d (diff)
downloadlinux-linaro-stable-c4e8d54f595b01d30e9b2793413d44f83deb7450.tar.gz
dcache.c: create helper function for duplicated functionality
commit c826cb7dfce80512c26c984350077a25046bd215 upstream. This creates a helper function for he "try to ascend into the parent directory" case, which was written out in triplicate before. With all the locking and subtle sequence number stuff, we really don't want to duplicate that kind of code. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs')
-rw-r--r--fs/dcache.c88
1 files changed, 37 insertions, 51 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 611ffe928c03..361882a14ccb 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1012,6 +1012,34 @@ void shrink_dcache_for_umount(struct super_block *sb)
}
/*
+ * 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
+ * that the sequence number still matches.
+ */
+static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
+{
+ struct dentry *new = old->d_parent;
+
+ rcu_read_lock();
+ spin_unlock(&old->d_lock);
+ spin_lock(&new->d_lock);
+
+ /*
+ * might go back up the wrong parent if we have had a rename
+ * or deletion
+ */
+ if (new != old->d_parent ||
+ (!locked && read_seqretry(&rename_lock, seq))) {
+ spin_unlock(&new->d_lock);
+ new = NULL;
+ }
+ rcu_read_unlock();
+ return new;
+}
+
+
+/*
* Search for at least 1 mount point in the dentry's subdirs.
* We descend to the next level whenever the d_subdirs
* list is non-empty and continue searching.
@@ -1066,24 +1094,10 @@ resume:
* All done at this level ... ascend and resume the search.
*/
if (this_parent != parent) {
- struct dentry *tmp;
- struct dentry *child;
-
- tmp = this_parent->d_parent;
- rcu_read_lock();
- spin_unlock(&this_parent->d_lock);
- child = this_parent;
- this_parent = tmp;
- spin_lock(&this_parent->d_lock);
- /* might go back up the wrong parent if we have had a rename
- * or deletion */
- if (this_parent != child->d_parent ||
- (!locked && read_seqretry(&rename_lock, seq))) {
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
+ struct dentry *child = this_parent;
+ this_parent = try_to_ascend(this_parent, locked, seq);
+ if (!this_parent)
goto rename_retry;
- }
- rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}
@@ -1181,24 +1195,10 @@ resume:
* All done at this level ... ascend and resume the search.
*/
if (this_parent != parent) {
- struct dentry *tmp;
- struct dentry *child;
-
- tmp = this_parent->d_parent;
- rcu_read_lock();
- spin_unlock(&this_parent->d_lock);
- child = this_parent;
- this_parent = tmp;
- spin_lock(&this_parent->d_lock);
- /* might go back up the wrong parent if we have had a rename
- * or deletion */
- if (this_parent != child->d_parent ||
- (!locked && read_seqretry(&rename_lock, seq))) {
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
+ struct dentry *child = this_parent;
+ this_parent = try_to_ascend(this_parent, locked, seq);
+ if (!this_parent)
goto rename_retry;
- }
- rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}
@@ -2942,28 +2942,14 @@ resume:
spin_unlock(&dentry->d_lock);
}
if (this_parent != root) {
- struct dentry *tmp;
- struct dentry *child;
-
- tmp = this_parent->d_parent;
+ struct dentry *child = this_parent;
if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
this_parent->d_flags |= DCACHE_GENOCIDE;
this_parent->d_count--;
}
- rcu_read_lock();
- spin_unlock(&this_parent->d_lock);
- child = this_parent;
- this_parent = tmp;
- spin_lock(&this_parent->d_lock);
- /* might go back up the wrong parent if we have had a rename
- * or deletion */
- if (this_parent != child->d_parent ||
- (!locked && read_seqretry(&rename_lock, seq))) {
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
+ this_parent = try_to_ascend(this_parent, locked, seq);
+ if (!this_parent)
goto rename_retry;
- }
- rcu_read_unlock();
next = child->d_u.d_child.next;
goto resume;
}