On Thu, 2 Apr 2015 14:51:35 +0100
Sachin Prabhu <sprabhu@xxxxxxxxxx> wrote:
> Doing a readdir on a dfs root can result in the dentries for directories
> with a dfs share mounted being replaced by new dentries for objects
> returned by the readdir call. These new dentries on shares mounted with
> unix extenstions show up as symlinks pointing to the dfs share.
>
> # mount -t cifs -o sec=none //vm140-31/dfsroot cifs
> # stat cifs/testlink/testfile; ls -l cifs
> File: ‘cifs/testlink/testfile’
> Size: 0 Blocks: 0 IO Block: 16384 regular
> empty file
> Device: 27h/39d Inode: 130120 Links: 1
> Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
> Access: 2015-03-31 13:55:50.106018200 +0100
> Modify: 2015-03-31 13:55:50.106018200 +0100
> Change: 2015-03-31 13:55:50.106018200 +0100
> Birth: -
> total 0
> drwxr-xr-x 2 root root 0 Mar 31 13:54 testdir
> lrwxrwxrwx 1 root root 19 Mar 24 14:25 testlink -> \vm140-31\test
>
> In the example above, the stat command mounts the dfs share at
> cifs/testlink. The subsequent ls on the dfsroot directory replaces the
> dentry for testlink with a symlink.
>
> In the earlier code, the d_invalidate command returned an -EBUSY error
> when attempting to invalidate directories. This stopped the code from
> replacing the directories with symlinks returned by the readdir call.
> Changes were recently made to the d_invalidate() command so
> that it no longer returns an error code. This results in the directory
> with the mounted dfs share being replaced by a symlink which denotes a
> dfs share.
>
> Signed-off-by: Sachin Prabhu <sprabhu@xxxxxxxxxx>
> ---
> fs/cifs/readdir.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
> index c295338..b4bda47 100644
> --- a/fs/cifs/readdir.c
> +++ b/fs/cifs/readdir.c
> @@ -90,6 +90,8 @@ cifs_prime_dcache(struct dentry *parent, struct qstr *name,
> if (dentry) {
> inode = dentry->d_inode;
> if (inode) {
> + if (d_mountpoint(dentry))
> + goto out;
> /*
> * If we're generating inode numbers, then we don't
> * want to clobber the existing one with the one that
Looks right.
Reviewed-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
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