fat: Fix vfat_lookup()
After d_find_alias(), vfat_lookup() checks !(->d_flags & DCACHE_DISCONNECTED)
without IS_ROOT(). This means it hits non-anonymous but disconnected
dentry. (NOTE: d_splice_alias() doesn't clear DCACHE_DISCONNECTED)
But, vfat_lookup() has interest to alias if it was non-anonymous. So,
this adds vfat_d_anon_disconn() helper to check it correctly.
Another bug is refcnt leak. It needs dput() for uninterested alias.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index f565f24..411c192 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -701,6 +701,15 @@
return fat_search_long(dir, qname->name, len, sinfo);
}
+/*
+ * (nfsd's) anonymous disconnected dentry?
+ * NOTE: !IS_ROOT() is not anonymous (I.e. d_splice_alias() did the job).
+ */
+static int vfat_d_anon_disconn(struct dentry *dentry)
+{
+ return IS_ROOT(dentry) && (dentry->d_flags & DCACHE_DISCONNECTED);
+}
+
static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
@@ -729,11 +738,11 @@
}
alias = d_find_alias(inode);
- if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) {
+ if (alias && !vfat_d_anon_disconn(alias)) {
/*
- * This inode has non DCACHE_DISCONNECTED dentry. This
- * means, the user did ->lookup() by an another name
- * (longname vs 8.3 alias of it) in past.
+ * This inode has non anonymous-DCACHE_DISCONNECTED
+ * dentry. This means, the user did ->lookup() by an
+ * another name (longname vs 8.3 alias of it) in past.
*
* Switch to new one for reason of locality if possible.
*/
@@ -743,7 +752,9 @@
iput(inode);
unlock_super(sb);
return alias;
- }
+ } else
+ dput(alias);
+
out:
unlock_super(sb);
dentry->d_op = sb->s_root->d_op;