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authorDavid Howells <dhowells@redhat.com>2010-02-19 18:14:21 +0000
committerAl Viro <viro@zeniv.linux.org.uk>2010-02-20 10:06:35 -0500
commit8f9941aeccc318f243ab3fa55aaa17f4c1cb33f9 (patch)
treea18890c2ace7ffde0682e29c58230ffc1fcdde15 /fs
parentaeaa5ccd6421fbf9e7ded0ac67b12ea2b9fcf51e (diff)
downloadlinux-8f9941aeccc318f243ab3fa55aaa17f4c1cb33f9.tar.gz
CacheFiles: Fix a race in cachefiles_delete_object() vs rename
cachefiles_delete_object() can race with rename. It gets the parent directory of the object it's asked to delete, then locks it - but rename may have changed the object's parent between the get and the completion of the lock. However, if such a circumstance is detected, we abandon our attempt to delete the object - since it's no longer in the index key path, it won't be seen again by lookups of that key. The assumption is that cachefilesd may have culled it by renaming it to the graveyard for later destruction. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/cachefiles/namei.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 14ac4806e29..eeb4986ea7d 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -348,7 +348,17 @@ int cachefiles_delete_object(struct cachefiles_cache *cache,
dir = dget_parent(object->dentry);
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
- ret = cachefiles_bury_object(cache, dir, object->dentry);
+
+ /* we need to check that our parent is _still_ our parent - it may have
+ * been renamed */
+ if (dir == object->dentry->d_parent) {
+ ret = cachefiles_bury_object(cache, dir, object->dentry);
+ } else {
+ /* it got moved, presumably by cachefilesd culling it, so it's
+ * no longer in the key path and we can ignore it */
+ mutex_unlock(&dir->d_inode->i_mutex);
+ ret = 0;
+ }
dput(dir);
_leave(" = %d", ret);