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authorAl Viro <viro@zeniv.linux.org.uk>2014-10-26 19:31:10 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-05-17 09:53:51 -0700
commit9cf2961ba6adaa14e06e1aa48fc65dadea49f9e2 (patch)
tree0dc55d8eb0218ff727a0a20114be9d78b0ef3349 /fs
parentd74ebe01a4fdfd0d1b95ca47dcd9f197653ca672 (diff)
downloadlinux-linaro-stable-9cf2961ba6adaa14e06e1aa48fc65dadea49f9e2.tar.gz
deal with deadlock in d_walk()
commit ca5358ef75fc69fee5322a38a340f5739d997c10 upstream. ... by not hitting rename_retry for reasons other than rename having happened. In other words, do _not_ restart when finding that between unlocking the child and locking the parent the former got into __dentry_kill(). Skip the killed siblings instead... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Ben Hutchings <ben@decadent.org.uk> [hujianyang: Backported to 3.14 refer to the work of Ben Hutchings in 3.2: - Adjust context to make __dentry_kill() apply to d_kill()] Signed-off-by: hujianyang <hujianyang@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/dcache.c31
1 files changed, 16 insertions, 15 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index c345f5f2b508..a9231c872342 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -435,7 +435,7 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
__releases(parent->d_lock)
__releases(dentry->d_inode->i_lock)
{
- list_del(&dentry->d_child);
+ __list_del_entry(&dentry->d_child);
/*
* Inform d_walk() that we are no longer attached to the
* dentry tree
@@ -1123,33 +1123,31 @@ resume:
/*
* All done at this level ... ascend and resume the search.
*/
+ rcu_read_lock();
+ascend:
if (this_parent != parent) {
struct dentry *child = this_parent;
this_parent = child->d_parent;
- rcu_read_lock();
spin_unlock(&child->d_lock);
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 ||
- (child->d_flags & DCACHE_DENTRY_KILLED) ||
- need_seqretry(&rename_lock, seq)) {
- spin_unlock(&this_parent->d_lock);
- rcu_read_unlock();
+ /* might go back up the wrong parent if we have had a rename. */
+ if (need_seqretry(&rename_lock, seq))
goto rename_retry;
+ next = child->d_child.next;
+ while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)) {
+ if (next == &this_parent->d_subdirs)
+ goto ascend;
+ child = list_entry(next, struct dentry, d_child);
+ next = next->next;
}
rcu_read_unlock();
- next = child->d_child.next;
goto resume;
}
- if (need_seqretry(&rename_lock, seq)) {
- spin_unlock(&this_parent->d_lock);
+ if (need_seqretry(&rename_lock, seq))
goto rename_retry;
- }
+ rcu_read_unlock();
if (finish)
finish(data);
@@ -1159,6 +1157,9 @@ out_unlock:
return;
rename_retry:
+ spin_unlock(&this_parent->d_lock);
+ rcu_read_unlock();
+ BUG_ON(seq & 1);
if (!retry)
return;
seq = 1;