ACK/cmnt: [PATCH][SRU][Disco] UBUNTU: SAUCE: shiftfs: enable overlayfs on shiftfs

[Kleber Souza]

On 8/13/19 7:57 AM, Christian Brauner wrote:
> On August 12, 2019 4:02:33 PM GMT+02:00, Kleber Souza <kleber.souza at canonical.com> wrote:
>> On 8/1/19 8:08 PM, Christian Brauner wrote:
>>> From: Christian Brauner <christian.brauner at canonical.com>
>>>
>>> BugLink: https://bugs.launchpad.net/bugs/1838677
>>>
>>> This patch enables overlayfs to use shiftfs as an underlay.
>>>
>>> Currently it is not possible to use overlayfs on top of shiftfs. This
>>> means Docker inside of LXD cannot make user of the overlay2 graph
>> driver
>>> which is blocking users such as Travis from making use of it
>>> efficiently.
>>>
>>> Co-Developed-by: Seth Forshee <seth.forshee at canonical.com>
>>> Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
>>> Signed-off-by: Christian Brauner <christian.brauner at canonical.com>
>>
>> Hi Christian,
>>
>> The LP bug states:
>>
>>> Target kernels: All LTS kernels that do support shiftfs, if possible.
>>
>> Will this patch be submitted for Bionic and Xenial as well?
> 
> Sorry, was on vacation.
> It should go into all kernels that have shiftfs support. :)
> Seth probably knows better whether we have this in Bionic and Xenial. I reckon we do.
> Seth, do I need to submit this separate patches?

The file 'fs/shiftfs.c' doesn't exist in B/X, so I assume
it's not needed beyond Disco.


Thanks,
Kleber

> 
> Christian
> 
>>
>>
>> Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
>>
>> Thanks,
>> Kleber
>>
>>> ---
>>>  fs/open.c            | 4 +++-
>>>  fs/overlayfs/file.c  | 1 +
>>>  fs/overlayfs/super.c | 5 +++--
>>>  fs/shiftfs.c         | 4 +++-
>>>  include/linux/fs.h   | 3 ++-
>>>  5 files changed, 12 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/fs/open.c b/fs/open.c
>>> index 14502dde6403..b8268a334dc9 100644
>>> --- a/fs/open.c
>>> +++ b/fs/open.c
>>> @@ -914,13 +914,15 @@ struct file *dentry_open(const struct path
>> *path, int flags,
>>>  EXPORT_SYMBOL(dentry_open);
>>>  
>>>  struct file *open_with_fake_path(const struct path *path, int flags,
>>> -				struct inode *inode, const struct cred *cred)
>>> +				 struct inode *inode, struct dentry *dentry,
>>> +				 const struct cred *cred)
>>>  {
>>>  	struct file *f = alloc_empty_file_noaccount(flags, cred);
>>>  	if (!IS_ERR(f)) {
>>>  		int error;
>>>  
>>>  		f->f_path = *path;
>>> +		f->f_path.dentry = dentry;
>>>  		error = do_dentry_open(f, inode, NULL);
>>>  		if (error) {
>>>  			fput(f);
>>> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
>>> index 6f6eb638a320..fe61b86c843b 100644
>>> --- a/fs/overlayfs/file.c
>>> +++ b/fs/overlayfs/file.c
>>> @@ -33,6 +33,7 @@ static struct file *ovl_open_realfile(const struct
>> file *file,
>>>  
>>>  	old_cred = ovl_override_creds(inode->i_sb);
>>>  	realfile = open_with_fake_path(&file->f_path, flags, realinode,
>>> +				       ovl_dentry_real(file->f_path.dentry),
>>>  				       current_cred());
>>>  	revert_creds(old_cred);
>>>  
>>> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
>>> index bb2a6f80ffd0..46def89a3664 100644
>>> --- a/fs/overlayfs/super.c
>>> +++ b/fs/overlayfs/super.c
>>> @@ -748,13 +748,14 @@ static int ovl_mount_dir(const char *name,
>> struct path *path)
>>>  		ovl_unescape(tmp);
>>>  		err = ovl_mount_dir_noesc(tmp, path);
>>>  
>>> -		if (!err)
>>> -			if (ovl_dentry_remote(path->dentry)) {
>>> +		if (!err) {
>>> +			if ((path->dentry->d_sb->s_magic != SHIFTFS_MAGIC) &&
>> ovl_dentry_remote(path->dentry)) {
>>>  				pr_err("overlayfs: filesystem on '%s' not supported as
>> upperdir\n",
>>>  				       tmp);
>>>  				path_put_init(path);
>>>  				err = -EINVAL;
>>>  			}
>>> +		}
>>>  		kfree(tmp);
>>>  	}
>>>  	return err;
>>> diff --git a/fs/shiftfs.c b/fs/shiftfs.c
>>> index 49f6714e9f95..400c3062365c 100644
>>> --- a/fs/shiftfs.c
>>> +++ b/fs/shiftfs.c
>>> @@ -1048,7 +1048,9 @@ static struct file *shiftfs_open_realfile(const
>> struct file *file,
>>>  	oldcred = shiftfs_override_creds(inode->i_sb);
>>>  	/* XXX: open_with_fake_path() not gauranteed to stay around, if
>>>  	 * removed use dentry_open() */
>>> -	lowerf = open_with_fake_path(realpath, file->f_flags, loweri,
>> info->creator_cred);
>>> +	lowerf = open_with_fake_path(realpath, file->f_flags, loweri,
>>> +				     realpath->dentry,
>>> +				     info->creator_cred);
>>>  	revert_creds(oldcred);
>>>  
>>>  	return lowerf;
>>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>>> index 5dd548c73f8d..4cb7a1124c5f 100644
>>> --- a/include/linux/fs.h
>>> +++ b/include/linux/fs.h
>>> @@ -2524,7 +2524,8 @@ extern struct file *file_open_root(struct
>> dentry *, struct vfsmount *,
>>>  				   const char *, int, umode_t);
>>>  extern struct file * dentry_open(const struct path *, int, const
>> struct cred *);
>>>  extern struct file * open_with_fake_path(const struct path *, int,
>>> -					 struct inode*, const struct cred *);
>>> +					 struct inode*, struct dentry *dentry,
>>> +					 const struct cred *);
>>>  static inline struct file *file_clone_open(struct file *file)
>>>  {
>>>  	return dentry_open(&file->f_path, file->f_flags, file->f_cred);
>>>
>