Enable previous version support

Add ioctl to query previous versions of file

Allows listing snapshots on files on SMB3 mounts.
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/cifs_ioctl.h

@@ -36,7 +36,15 @@ struct smb_mnt_fs_info {
 	__u64   cifs_posix_caps;
 } __packed;
 
+struct smb_snapshot_array {
+	__u32	number_of_snapshots;
+	__u32	number_of_snapshots_returned;
+	__u32	snapshot_array_size;
+	/*	snapshots[]; */
+} __packed;
+
 #define CIFS_IOCTL_MAGIC	0xCF
 #define CIFS_IOC_COPYCHUNK_FILE	_IOW(CIFS_IOCTL_MAGIC, 3, int)
 #define CIFS_IOC_SET_INTEGRITY  _IO(CIFS_IOCTL_MAGIC, 4)
 #define CIFS_IOC_GET_MNT_INFO _IOR(CIFS_IOCTL_MAGIC, 5, struct smb_mnt_fs_info)
+#define CIFS_ENUMERATE_SNAPSHOTS _IOR(CIFS_IOCTL_MAGIC, 6, struct smb_snapshot_array)

fs/cifs/cifsglob.h

@@ -388,6 +388,8 @@ struct smb_version_operations {
 	int (*calc_signature)(struct smb_rqst *, struct TCP_Server_Info *);
 	int (*set_integrity)(const unsigned int, struct cifs_tcon *tcon,
 			     struct cifsFileInfo *src_file);
+	int (*enum_snapshots)(const unsigned int xid, struct cifs_tcon *tcon,
+			     struct cifsFileInfo *src_file, void __user *);
 	int (*query_mf_symlink)(unsigned int, struct cifs_tcon *,
 				struct cifs_sb_info *, const unsigned char *,
 				char *, unsigned int *);

fs/cifs/ioctl.c

@@ -189,7 +189,7 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
 	xid = get_xid();
 
 	cifs_sb = CIFS_SB(inode->i_sb);
-
+	cifs_dbg(VFS, "cifs ioctl 0x%x\n", command);
 	switch (command) {
 		case FS_IOC_GETFLAGS:
 			if (pSMBFile == NULL)
@@ -267,11 +267,23 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
 			tcon = tlink_tcon(pSMBFile->tlink);
 			rc = smb_mnt_get_fsinfo(xid, tcon, (void __user *)arg);
 			break;
+		case CIFS_ENUMERATE_SNAPSHOTS:
+			if (arg == 0) {
+				rc = -EINVAL;
+				goto cifs_ioc_exit;
+			}
+			tcon = tlink_tcon(pSMBFile->tlink);
+			if (tcon->ses->server->ops->enum_snapshots)
+				rc = tcon->ses->server->ops->enum_snapshots(xid, tcon,
+						pSMBFile, (void __user *)arg);
+			else
+				rc = -EOPNOTSUPP;
+			break;
 		default:
 			cifs_dbg(FYI, "unsupported ioctl\n");
 			break;
 	}
-
+cifs_ioc_exit:
 	free_xid(xid);
 	return rc;
 }

fs/cifs/smb2ops.c

@@ -28,6 +28,7 @@
 #include "cifs_unicode.h"
 #include "smb2status.h"
 #include "smb2glob.h"
+#include "cifs_ioctl.h"
 
 static int
 change_conf(struct TCP_Server_Info *server)
@@ -894,6 +895,50 @@ smb3_set_integrity(const unsigned int xid, struct cifs_tcon *tcon,
 
 }
 
+static int
+smb3_enum_snapshots(const unsigned int xid, struct cifs_tcon *tcon,
+		   struct cifsFileInfo *cfile, void __user *ioc_buf)
+{
+	char *retbuf = NULL;
+	unsigned int ret_data_len = 0;
+	int rc;
+	struct smb_snapshot_array snapshot_in;
+
+	rc = SMB2_ioctl(xid, tcon, cfile->fid.persistent_fid,
+			cfile->fid.volatile_fid,
+			FSCTL_SRV_ENUMERATE_SNAPSHOTS,
+			true /* is_fsctl */, NULL, 0 /* no input data */,
+			(char **)&retbuf,
+			&ret_data_len);
+	cifs_dbg(FYI, "enum snaphots ioctl returned %d and ret buflen is %d\n",
+			rc, ret_data_len);
+	if (rc)
+		return rc;
+
+	if (ret_data_len && (ioc_buf != NULL) && (retbuf != NULL)) {
+		/* Fixup buffer */
+		if (copy_from_user(&snapshot_in, ioc_buf,
+		    sizeof(struct smb_snapshot_array))) {
+			rc = -EFAULT;
+			kfree(retbuf);
+			return rc;
+		}
+		if (snapshot_in.snapshot_array_size < sizeof(struct smb_snapshot_array)) {
+			rc = -ERANGE;
+			return rc;
+		}
+
+		if (ret_data_len > snapshot_in.snapshot_array_size)
+			ret_data_len = snapshot_in.snapshot_array_size;
+
+		if (copy_to_user(ioc_buf, retbuf, ret_data_len))
+			rc = -EFAULT;
+	}
+
+	kfree(retbuf);
+	return rc;
+}
+
 static int
 smb2_query_dir_first(const unsigned int xid, struct cifs_tcon *tcon,
 		     const char *path, struct cifs_sb_info *cifs_sb,
@@ -1659,6 +1704,7 @@ struct smb_version_operations smb21_operations = {
 	.clone_range = smb2_clone_range,
 	.wp_retry_size = smb2_wp_retry_size,
 	.dir_needs_close = smb2_dir_needs_close,
+	.enum_snapshots = smb3_enum_snapshots,
 };
 
 struct smb_version_operations smb30_operations = {
@@ -1745,6 +1791,7 @@ struct smb_version_operations smb30_operations = {
 	.wp_retry_size = smb2_wp_retry_size,
 	.dir_needs_close = smb2_dir_needs_close,
 	.fallocate = smb3_fallocate,
+	.enum_snapshots = smb3_enum_snapshots,
 };
 
 #ifdef CONFIG_CIFS_SMB311
@@ -1832,6 +1879,7 @@ struct smb_version_operations smb311_operations = {
 	.wp_retry_size = smb2_wp_retry_size,
 	.dir_needs_close = smb2_dir_needs_close,
 	.fallocate = smb3_fallocate,
+	.enum_snapshots = smb3_enum_snapshots,
 };
 #endif /* CIFS_SMB311 */