Re: [PATCHv2] Add reflink copy over SMB3.11 with new FSCTL_DUPLICATE_EXTENTS

["Darrick J. Wong" <darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On Mon, Jun 29, 2015 at 02:33:56PM -0500, Steve French wrote:
> On Mon, Jun 29, 2015 at 12:27 PM, Darrick J. Wong
> <darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
> >
> > On Sun, Jun 28, 2015 at 09:21:05PM -0500, Steve French wrote:
> > >  Update the patch to correct target file size.
> > >
> > >  Getting fantastic copy performance with cp --reflink over SMB3.11
> > >  using the new FSCTL_DUPLICATE_EXTENTS.
> > >
> > >  This FSCTL was added in the SMB3.11 dialect (testing was
> > >  against REFS file system) so have put it as a 3.11 protocol
> > >  specific operation ("vers=3.1.1" on the mount).  Tested at
> > >  the SMB3 plugfest in Redmond.
> > >
> > >  It depends on the new FS Attribute (BLOCK_REFCOUNTING) which
> > >  is used to advertise support for the ability to do this ioctl
> > >  (if you can support multiple files pointing to the same block
> > >  than this refcounting ability or equivalent is needed to
> > >  support the new reflink-like duplicate extent SMB3 ioctl.
> > >
> > > Signed-off-by: Steve French <steve.french-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>
> > > ---
> > >  fs/cifs/cifsglob.h |  3 +++
> > >  fs/cifs/cifspdu.h  |  2 ++
> > >  fs/cifs/ioctl.c    | 16 +++++++++++++---
> > >  fs/cifs/smb2ops.c  | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> > >  fs/cifs/smb2pdu.h  |  8 ++++++++
> > >  fs/cifs/smbfsctl.h |  1 +
> > >  6 files changed, 75 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> > > index a0212ec..81194e6 100644
> > > --- a/fs/cifs/cifsglob.h
> > > +++ b/fs/cifs/cifsglob.h
> > > @@ -390,6 +390,9 @@ struct smb_version_operations {
> > >       int (*clone_range)(const unsigned int, struct cifsFileInfo *src_file,
> > >                       struct cifsFileInfo *target_file, u64 src_off, u64 len,
> > >                       u64 dest_off);
> > > +     int (*duplicate_extents)(const unsigned int, struct cifsFileInfo *src,
> > > +                     struct cifsFileInfo *target_file, u64 src_off, u64 len,
> > > +                     u64 dest_off);
> > >       int (*validate_negotiate)(const unsigned int, struct cifs_tcon *);
> > >       ssize_t (*query_all_EAs)(const unsigned int, struct cifs_tcon *,
> > >                       const unsigned char *, const unsigned char *, char *,
> > > diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
> > > index 998a66f..47b030d 100644
> > > --- a/fs/cifs/cifspdu.h
> > > +++ b/fs/cifs/cifspdu.h
> > > @@ -2255,6 +2255,8 @@ typedef struct {
> > >
> > >
> > >  /* List of FileSystemAttributes - see 2.5.1 of MS-FSCC */
> > > +#define FILE_SUPPORTS_SPARSE_VDL     0x10000000 /* faster nonsparse extend */
> > > +#define FILE_SUPPORTS_BLOCK_REFCOUNTING      0x08000000 /* allow ioctl dup extents */
> > >  #define FILE_SUPPORT_INTEGRITY_STREAMS       0x04000000
> > >  #define FILE_SUPPORTS_USN_JOURNAL    0x02000000
> > >  #define FILE_SUPPORTS_OPEN_BY_FILE_ID        0x01000000
> > > diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c
> > > index 8b7898b..7843b19 100644
> > > --- a/fs/cifs/ioctl.c
> > > +++ b/fs/cifs/ioctl.c
> > > @@ -31,12 +31,14 @@
> > >  #include "cifsproto.h"
> > >  #include "cifs_debug.h"
> > >  #include "cifsfs.h"
> > > +#include <linux/btrfs.h>
> > >
> > >  #define CIFS_IOCTL_MAGIC     0xCF
> > >  #define CIFS_IOC_COPYCHUNK_FILE      _IOW(CIFS_IOCTL_MAGIC, 3, int)
> > >
> > >  static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
> > > -                     unsigned long srcfd, u64 off, u64 len, u64 destoff)
> > > +                     unsigned long srcfd, u64 off, u64 len, u64 destoff,
> > > +                     bool dup_extents)
> > >  {
> > >       int rc;
> > >       struct cifsFileInfo *smb_file_target = dst_file->private_data;
> > > @@ -109,9 +111,14 @@ static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
> > >       truncate_inode_pages_range(&target_inode->i_data, destoff,
> > >                                  PAGE_CACHE_ALIGN(destoff + len)-1);
> > >
> > > -     if (target_tcon->ses->server->ops->clone_range)
> > > +     if (dup_extents && target_tcon->ses->server->ops->duplicate_extents)
> > > +             rc = target_tcon->ses->server->ops->duplicate_extents(xid,
> > > +                     smb_file_src, smb_file_target, off, len, destoff);
> > > +     else if (!dup_extents && target_tcon->ses->server->ops->clone_range)
> > >               rc = target_tcon->ses->server->ops->clone_range(xid,
> > >                       smb_file_src, smb_file_target, off, len, destoff);
> > > +     else
> > > +             rc = -EOPNOTSUPP;
> > >
> > >       /* force revalidate of size and timestamps of target file now
> > >          that target is updated on the server */
> > > @@ -205,7 +212,10 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
> > >                       }
> > >                       break;
> > >               case CIFS_IOC_COPYCHUNK_FILE:
> > > -                     rc = cifs_ioctl_clone(xid, filep, arg, 0, 0, 0);
> > > +                     rc = cifs_ioctl_clone(xid, filep, arg, 0, 0, 0, false);
> > > +                     break;
> > > +             case BTRFS_IOC_CLONE:
> > > +                     rc = cifs_ioctl_clone(xid, filep, arg, 0, 0, 0, true);
> >
> > Any interest in supporting BTRFS_IOC_CLONE_RANGE or BTRFS_IOC_EXTENT_SAME?
> > It looks like you could easily support the former, and the latter would
> > enable things like duperemove.  I've been working on a pile of xfstests to
> > exercise these three ioctls, will post them later today, I hope.
> >
> > --D
> >
> 
> So far Samba (server) only uses three btrfs ioctls, but that includes
> clone range:

Oh, my question was mostly about support for CLONE_RANGE within
cifs.ko so that clients could ask for a reflink, which would then be
sent off to the server as FSCTL_DUPLICATE_EXTENTS.  That doesn't seem
too hard, but I didn't see it in ioctl.c and wondered why. :)

> 
> ./source3/modules/vfs_btrfs.c:#define BTRFS_IOC_CLONE_RANGE ...
> ./source3/modules/vfs_btrfs.c:#define BTRFS_IOC_SNAP_DESTROY ...
> ./source3/modules/vfs_btrfs.c:#define BTRFS_IOC_SNAP_CREATE_V2 ...
> 
> But btrfs clone range is only (optionally if present) used to handle
> the "CopyChunk" API (SMB3 and CIFS network protocol requests), and
> Samba server doesn't have code for the FSCTL_DUPLICATE_EXTENTS fsctl
> (SMB3 network protocol request) yet.  It looks trivial to map that to
> BTRFS_IOC_CLONE_RANGE in the Samba server.   Would need to add trivial
> parsing in smbd/smb2_ioctl_network_fs.c and a new VFS entry point in
> the Samba VFS and a small helper routine in
> source3/modules/vfs_btrfs.c

Sounds fairly straightforward on the server side.  I'm working on adding
the three ioctls I mentioned (CLONE, CLONE_RANGE, EXTENT_SAME) to XFS and
others are working on it for ext4; do you think it would be difficult to
adapt Samba server to talk to these three btrfs APIs even with a non-btrfs
backend?

(Or, maybe someday we might refactor all this into a common syscall or
something.)

I guess BTRFS_IOC_EXTENT_SAME would be harder since you'd want to compare
file contents on the server, and I'm not sure if SMB can actually do that.

--D

> 
> 
> -- 
> 
> Steve French
> 
> Principal Systems Engineer: Protocols
> 
> W: 512-918-9276
> 
> C:  512-501-9669
> 
> www.primarydata.com
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