Add reflink copy over SMB3.11 with new FSCTL_DUPLICATE_EXTENTS

 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@primarydata.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index c7d228c4006a..b1e9c0f1b24c 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -806,6 +806,53 @@ smb2_set_file_size(const unsigned int xid, struct cifs_tcon *tcon,
 			    cfile->fid.volatile_fid, cfile->pid, &eof, false);
 }
 
+#ifdef CONFIG_CIFS_SMB311
+static int
+smb2_duplicate_extents(const unsigned int xid,
+			struct cifsFileInfo *srcfile,
+			struct cifsFileInfo *trgtfile, u64 src_off,
+			u64 len, u64 dest_off)
+{
+	int rc;
+	unsigned int ret_data_len;
+	char *retbuf = NULL;
+	struct duplicate_extents_to_file dup_ext_buf;
+	struct cifs_tcon *tcon = tlink_tcon(trgtfile->tlink);
+
+	/* server fileays advertise duplicate extent support with this flag */
+	if ((le32_to_cpu(tcon->fsAttrInfo.Attributes) &
+	     FILE_SUPPORTS_BLOCK_REFCOUNTING) == 0)
+		return -EOPNOTSUPP;
+
+	dup_ext_buf.VolatileFileHandle = srcfile->fid.volatile_fid;
+	dup_ext_buf.PersistentFileHandle = srcfile->fid.persistent_fid;
+	dup_ext_buf.SourceFileOffset = cpu_to_le64(src_off);
+	dup_ext_buf.TargetFileOffset = cpu_to_le64(dest_off);
+	dup_ext_buf.ByteCount = cpu_to_le64(len);
+	cifs_dbg(FYI, "duplicate extents: src off %lld dst off %lld len %lld",
+		src_off, dest_off, len);
+
+	rc = smb2_set_file_size(xid, tcon, trgtfile, dest_off + len, false);
+	if (rc)
+		goto duplicate_extents_out;
+
+	rc = SMB2_ioctl(xid, tcon, trgtfile->fid.persistent_fid,
+			trgtfile->fid.volatile_fid,
+			FSCTL_DUPLICATE_EXTENTS_TO_FILE,
+			true /* is_fsctl */, (char *)&dup_ext_buf,
+			sizeof(struct duplicate_extents_to_file),
+			(char **)&retbuf,
+			&ret_data_len);
+
+	if (ret_data_len > 0)
+		cifs_dbg(FYI, "non-zero response length in duplicate extents");
+
+duplicate_extents_out:
+	return rc;
+}
+#endif /* CONFIG_CIFS_SMB311 */
+
+
 static int
 smb2_set_compression(const unsigned int xid, struct cifs_tcon *tcon,
 		   struct cifsFileInfo *cfile)
@@ -1714,6 +1761,7 @@ struct smb_version_operations smb311_operations = {
 	.create_lease_buf = smb3_create_lease_buf,
 	.parse_lease_buf = smb3_parse_lease_buf,
 	.clone_range = smb2_clone_range,
+	.duplicate_extents = smb2_duplicate_extents,
 /*	.validate_negotiate = smb3_validate_negotiate, */ /* not used in 3.11 */
 	.wp_retry_size = smb2_wp_retry_size,
 	.dir_needs_close = smb2_dir_needs_close,