From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
Currently if d_splice_alias finds a directory with an alias that is not
IS_ROOT or not DCACHE_DISCONNECTED, it creates a duplicate directory.
Duplicate directory dentries are unacceptable; it is better just to
error out.
(In the case of a local filesystem the most likely case is filesystem
corruption: for example, perhaps two directories point to the same child
directory, and the other parent has already been found and cached.)
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
---
fs/dcache.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index fd50e52..4550227 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2672,6 +2672,9 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
* DCACHE_DISCONNECTED), then d_move that in place of the given dentry
* and return it, else simply d_add the inode to the dentry and return NULL.
*
+ * If a non-IS_ROOT directory is found, the filesystem is corrupt, and
+ * we should error out: directories can't have multiple aliases.
+ *
* This is needed in the lookup routine of any filesystem that is exportable
* (via knfsd) so that we can build dcache paths to directories effectively.
*
@@ -2692,9 +2695,13 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
if (inode && S_ISDIR(inode->i_mode)) {
spin_lock(&inode->i_lock);
- new = __d_find_alias(inode, 1);
+ new = __d_find_any_alias(inode);
if (new) {
- BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
+ if (!IS_ROOT(new) || !(new->d_flags & DCACHE_DISCONNECTED)) {
+ spin_unlock(&inode->i_lock);
+ dput(new);
+ return ERR_PTR(-EIO);
+ }
write_seqlock(&rename_lock);
__d_materialise_dentry(dentry, new);
write_sequnlock(&rename_lock);
--
1.8.5.3
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