Re: [PATCH v5 1/2] cifs: Alternate Data Streams: Add support

[Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>]

Btw, please CC linux-fsdevel and Al on these.

On Mon, Oct 22, 2012 at 12:01:22AM -0500, shirishpargaonkar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
> From: Shirish Pargaonkar <shirishpargaonkar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> 
> 
> Add support of Alternate Data Streams (ads).
> 
> The generic access flags that cifs client currently employs are sufficient
> for alternate data streams as well (MS-CIFS 2.2.4.64.1).
> 
> The stream file and stream type are specified using : after the file name,
> so that is used to differentiate between a regular file and its
> alternate data streams and stream types.
> Since they all have the same file id, each path name,
> file name:stream name:stream type, has a separate inode with that same
> file id but a distinct private data (path name) in that inode to
> distinguish them.
> 
> This scheme applies only to non-posix compliant servers such as Windows.
> 
> One operation that does not work is Rename (0x7).
> 
> 
> Signed-off-by: Shirish Pargaonkar <shirishpargaonkar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  fs/cifs/cifsfs.c   |    1 +
>  fs/cifs/cifsglob.h |    2 ++
>  fs/cifs/inode.c    |   31 ++++++++++++++++++++++++++++++-
>  3 files changed, 33 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 5e62f44..0f11fb5 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -263,6 +263,7 @@ cifs_evict_inode(struct inode *inode)
>  {
>  	truncate_inode_pages(&inode->i_data, 0);
>  	clear_inode(inode);
> +	kfree(inode->i_private);
>  	cifs_fscache_release_inode_cookie(inode);
>  }
>  
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index f5af252..26d65c7 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -1251,6 +1251,7 @@ struct dfs_info3_param {
>  #define CIFS_FATTR_DELETE_PENDING	0x2
>  #define CIFS_FATTR_NEED_REVAL		0x4
>  #define CIFS_FATTR_INO_COLLISION	0x8
> +#define CIFS_FATTR_ALTDATASTR		0x10
>  
>  struct cifs_fattr {
>  	u32		cf_flags;
> @@ -1268,6 +1269,7 @@ struct cifs_fattr {
>  	struct timespec	cf_atime;
>  	struct timespec	cf_mtime;
>  	struct timespec	cf_ctime;
> +	char		*cf_private;
>  };
>  
>  static inline void free_dfs_info_param(struct dfs_info3_param *param)
> diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
> index ed6208f..3c5ca0a 100644
> --- a/fs/cifs/inode.c
> +++ b/fs/cifs/inode.c
> @@ -615,10 +615,12 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
>  	struct tcon_link *tlink;
>  	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
>  	char *buf = NULL;
> +	char *altstr = NULL;
>  	bool adjust_tz = false;
>  	struct cifs_fattr fattr;
>  	struct cifs_search_info *srchinf = NULL;
>  
> +	fattr.cf_private = NULL;
>  	tlink = cifs_sb_tlink(cifs_sb);
>  	if (IS_ERR(tlink))
>  		return PTR_ERR(tlink);
> @@ -746,9 +748,26 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
>  	}
>  
>  	if (!*inode) {
> +		altstr = strchr(full_path, ':');
> +		if (altstr) {
> +			fattr.cf_private = kstrdup(altstr, GFP_KERNEL);
> +			if (!fattr.cf_private) {
> +				rc = -ENOMEM;
> +				goto cgii_exit;
> +			}
> +			fattr.cf_flags |= CIFS_FATTR_ALTDATASTR;
> +		}
> +
>  		*inode = cifs_iget(sb, &fattr);
> -		if (!*inode)
> +		if (*inode) {
> +			if (altstr && !((*inode)->i_private))
> +				(*inode)->i_private = fattr.cf_private;
> +			else
> +				kfree(fattr.cf_private);
> +		} else {
>  			rc = -ENOMEM;
> +			kfree(fattr.cf_private);
> +		}
>  	} else {
>  		cifs_fattr_to_inode(*inode, &fattr);
>  	}
> @@ -784,6 +803,16 @@ cifs_find_inode(struct inode *inode, void *opaque)
>  	if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry))
>  		fattr->cf_flags |= CIFS_FATTR_INO_COLLISION;
>  
> +	/* looking for an inode of a alternate data stream (full pathname) */
> +	if (fattr->cf_flags & CIFS_FATTR_ALTDATASTR) {
> +		if (!(inode->i_private)) {
> +			return 0;
> +		} else {
> +			if (strcmp(inode->i_private, fattr->cf_private))
> +				return 0;
> +		}
> +	}
> +
>  	return 1;
>  }
>  
> -- 
> 1.6.0.2
> 
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