From b18dafc86bb879d2f38a1743985d7ceb283c2f4d Mon Sep 17 00:00:00 2001
From: Michel Lespinasse <walken@google.com>
Date: Mon, 26 Mar 2012 17:32:44 -0700
Subject: [PATCH] vfs: fix d_ancestor() case in d_materialize_unique
In d_materialise_unique() there are 3 subcases to the 'aliased dentry'
case; in two subcases the inode i_lock is properly released but this
does not occur in the -ELOOP subcase.
This seems to have been introduced by commit 1836750115f2 ("fix loop
checks in d_materialise_unique()").
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: stable@vger.kernel.org # v3.0+
[ Added a comment, and moved the unlock to where we generate the -ELOOP,
which seems to be more natural.
You probably can't actually trigger this without a buggy network file
server - d_materialize_unique() is for finding aliases on non-local
filesystems, and the d_ancestor() case is for a hardlinked directory
loop.
But we should be robust in the case of such buggy servers anyway. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/dcache.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index e9a07b2a0948..b60ddc41d783 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2404,6 +2404,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
if (d_ancestor(alias, dentry)) {
/* Check for loops */
actual = ERR_PTR(-ELOOP);
+ spin_unlock(&inode->i_lock);
} else if (IS_ROOT(alias)) {
/* Is this an anonymous mountpoint that we
* could splice into our tree? */
@@ -2413,7 +2414,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
goto found;
} else {
/* Nope, but we must(!) avoid directory
- * aliasing */
+ * aliasing. This drops inode->i_lock */
actual = __d_unalias(inode, dentry, alias);
}
write_sequnlock(&rename_lock);
--
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