cifs: Fix the target file was deleted when rename failed.

commit 9ffad9263b467efd8f8dc7ae1941a0a655a2bab2 upstream.

When xfstest generic/035, we found the target file was deleted
if the rename return -EACESS.

In cifs_rename2, we unlink the positive target dentry if rename
failed with EACESS or EEXIST, even if the target dentry is positived
before rename. Then the existing file was deleted.

We should just delete the target file which created during the
rename.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index c18c26a784533968a74b3df0d813edbc0de77b8e..a002e289a544992208226173d847c1671193d8d3 100644 (file)
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -1737,6 +1737,7 @@ cifs_rename2(struct inode *source_dir, struct dentry *source_dentry,
        FILE_UNIX_BASIC_INFO *info_buf_target;
        unsigned int xid;
        int rc, tmprc;
+       bool new_target = d_really_is_negative(target_dentry);
 
        if (flags & ~RENAME_NOREPLACE)
                return -EINVAL;
@@ -1813,8 +1814,13 @@ cifs_rename2(struct inode *source_dir, struct dentry *source_dentry,
         */
 
 unlink_target:
-       /* Try unlinking the target dentry if it's not negative */
-       if (d_really_is_positive(target_dentry) && (rc == -EACCES || rc == -EEXIST)) {
+       /*
+        * If the target dentry was created during the rename, try
+        * unlinking it if it's not negative
+        */
+       if (new_target &&
+           d_really_is_positive(target_dentry) &&
+           (rc == -EACCES || rc == -EEXIST)) {
                if (d_is_dir(target_dentry))
                        tmprc = cifs_rmdir(target_dir, target_dentry);
                else