[PATCH] r/o bind mounts: get callers of vfs_mknod/create/mkdir()

This takes care of all of the direct callers of vfs_mknod().
Since a few of these cases also handle normal file creation
as well, this also covers some calls to vfs_create().

So that we don't have to make three mnt_want/drop_write()
calls inside of the switch statement, we move some of its
logic outside of the switch and into a helper function
suggested by Christoph.

This also encapsulates a fix for mknod(S_IFREG) that Miklos
found.

[AV: merged mkdir handling, added missing nfsd pieces]

Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 2851d0d15048..1454afcc06c4 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -819,7 +819,11 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
                  */
                 mode = S_IFSOCK |
                        (SOCK_INODE(sock)->i_mode & ~current->fs->umask);
+                err = mnt_want_write(nd.path.mnt);
+                if (err)
+                        goto out_mknod_dput;
                 err = vfs_mknod(nd.path.dentry->d_inode, dentry, mode, 0);
+                mnt_drop_write(nd.path.mnt);
                 if (err)
                         goto out_mknod_dput;
                 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);