When Al Viro's VFS deadlock fix "deal with deadlock in d_walk()" was
backported to 3.10.y 3.4.y and 3.2.y stable kernel brances, the deadlock fix
was copied to 3 different places. Later, a bug in that code was discovered.
Al Viro's fix involved fixing only one part of code in mainline kernel. That
fix is called "d_walk() might skip too much".
3.10.y 3.4.y and 3.2.y stable kernel brances need that later fix copied to 3
different places. Greg Kroah-Hartman included Al Viro's "d_walk() might skip
too much" fix only once in 3.10.80 kernel, leaving 2 more places without a
fix.
The patch below was not written by me. I only applied Al Viro's "d_walk()
might skip too much" fix 2 more times to 3.10.80 kernel, and cheched that
the fixes went to correct places. With this patch applied, all 3 places that
I am aware of 3.10.y stable branch are now fixed.
Signed-off-by: Jari Ruusu <jariruusu@xxxxxxxxxxxxxxxxxxxxx>
--- linux-3.10.80/fs/dcache.c.OLD 2015-06-11 19:22:31.000000000 +0300
+++ linux-3.10.80/fs/dcache.c 2015-06-11 19:32:59.000000000 +0300
@@ -1053,13 +1053,13 @@
/* might go back up the wrong parent if we have had a rename. */
if (!locked && read_seqretry(&rename_lock, seq))
goto rename_retry;
- next = child->d_child.next;
- while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)) {
+ /* go into the first sibling still alive */
+ do {
+ next = child->d_child.next;
if (next == &this_parent->d_subdirs)
goto ascend;
child = list_entry(next, struct dentry, d_child);
- next = next->next;
- }
+ } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
rcu_read_unlock();
goto resume;
}
@@ -2977,13 +2977,13 @@
/* might go back up the wrong parent if we have had a rename. */
if (!locked && read_seqretry(&rename_lock, seq))
goto rename_retry;
- next = child->d_child.next;
- while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)) {
+ /* go into the first sibling still alive */
+ do {
+ next = child->d_child.next;
if (next == &this_parent->d_subdirs)
goto ascend;
child = list_entry(next, struct dentry, d_child);
- next = next->next;
- }
+ } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
rcu_read_unlock();
goto resume;
}
--
Jari Ruusu 4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD ACDF F073 3C80 8132 F189
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