Commit b18dafc8 authored Mar 26, 2012 by Michel Lespinasse Committed by Linus Torvalds Mar 28, 2012

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 18367501 ("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>

parent 6658a699

fs/dcache.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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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