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authorJ. Bruce Fields <bfields@redhat.com>2014-02-18 02:45:56 +0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-08-07 22:40:10 +0400
commit75a2352d0110960aeee1a28ddc09a55f97c99100 (patch)
tree09df0569f40eb0a50a752575fa7991c62b98a76b /fs/dcache.c
parent3f70bd51cb4405dc5cf8624292ffa474679fc9c7 (diff)
downloadlinux-75a2352d0110960aeee1a28ddc09a55f97c99100.tar.xz
dcache: close d_move race in d_splice_alias
d_splice_alias will d_move an IS_ROOT() directory dentry into place if one exists. This should be safe as long as the dentry remains IS_ROOT, but I can't see what guarantees that: once we drop the i_lock all we hold here is the i_mutex on an unrelated parent directory. Instead copy the logic of d_materialise_unique. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/dcache.c')
-rw-r--r--fs/dcache.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 8bdae36a095f..8c09db9bb2a4 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2676,9 +2676,14 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
new = __d_find_alias(inode, 1);
if (new) {
BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
+ write_seqlock(&rename_lock);
+ __d_materialise_dentry(dentry, new);
+ write_sequnlock(&rename_lock);
+ __d_drop(new);
+ _d_rehash(new);
+ spin_unlock(&new->d_lock);
spin_unlock(&inode->i_lock);
security_d_instantiate(new, inode);
- d_move(new, dentry);
iput(inode);
} else {
/* already taking inode->i_lock, so d_add() by hand */