vfs: make unlink() and rmdir() return ENOENT in preference to EROFS

If user space attempts to remove a non-existent file or directory, and
the file system is mounted read-only, return ENOENT instead of EROFS.
Either error code is arguably valid/correct, but ENOENT is a more
specific error message.

Reported-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index e2e4e8d..9802345 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2624,6 +2624,10 @@ static long do_rmdir(int dfd, const char __user *pathname)
        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto exit2;
+       if (!dentry->d_inode) {
+               error = -ENOENT;
+               goto exit3;
+       }
        error = mnt_want_write(nd.path.mnt);
        if (error)
                goto exit3;
@@ -2709,11 +2713,10 @@ static long do_unlinkat(int dfd, const char __user *pathname)
        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                /* Why not before? Because we want correct error value */
-               if (nd.last.name[nd.last.len])
-                       goto slashes;
                inode = dentry->d_inode;
-               if (inode)
-                       ihold(inode);
+               if (nd.last.name[nd.last.len] || !inode)
+                       goto slashes;
+               ihold(inode);
                error = mnt_want_write(nd.path.mnt);
                if (error)
                        goto exit2;