enable fallocate punch hole ("fallocate -p") for SMB3

Implement FALLOC_FL_PUNCH_HOLE (which does not change the file size
fortunately so this matches the behavior of the equivalent SMB3
fsctl call) for SMB3 mounts.  This allows "fallocate -p" to work.
It requires that the server support setting files as sparse
(which Windows allows).

Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/cifsfs.c

@@ -207,6 +207,19 @@ cifs_statfs(struct dentry *dentry, struct kstatfs *buf)
 	return 0;
 }
 
+static long cifs_fallocate(struct file *file, int mode, loff_t off, loff_t len)
+{
+	struct super_block *sb = file->f_path.dentry->d_sb;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+	struct TCP_Server_Info *server = tcon->ses->server;
+
+	if (server->ops->fallocate)
+		return server->ops->fallocate(file, tcon, mode, off, len);
+
+	return -EOPNOTSUPP;
+}
+
 static int cifs_permission(struct inode *inode, int mask)
 {
 	struct cifs_sb_info *cifs_sb;
@@ -909,6 +922,7 @@ const struct file_operations cifs_file_ops = {
 	.unlocked_ioctl	= cifs_ioctl,
 #endif /* CONFIG_CIFS_POSIX */
 	.setlease = cifs_setlease,
+	.fallocate = cifs_fallocate,
 };
 
 const struct file_operations cifs_file_strict_ops = {
@@ -928,6 +942,7 @@ const struct file_operations cifs_file_strict_ops = {
 	.unlocked_ioctl	= cifs_ioctl,
 #endif /* CONFIG_CIFS_POSIX */
 	.setlease = cifs_setlease,
+	.fallocate = cifs_fallocate,
 };
 
 const struct file_operations cifs_file_direct_ops = {
@@ -948,6 +963,7 @@ const struct file_operations cifs_file_direct_ops = {
 #endif /* CONFIG_CIFS_POSIX */
 	.llseek = cifs_llseek,
 	.setlease = cifs_setlease,
+	.fallocate = cifs_fallocate,
 };
 
 const struct file_operations cifs_file_nobrl_ops = {
@@ -966,6 +982,7 @@ const struct file_operations cifs_file_nobrl_ops = {
 	.unlocked_ioctl	= cifs_ioctl,
 #endif /* CONFIG_CIFS_POSIX */
 	.setlease = cifs_setlease,
+	.fallocate = cifs_fallocate,
 };
 
 const struct file_operations cifs_file_strict_nobrl_ops = {
@@ -984,6 +1001,7 @@ const struct file_operations cifs_file_strict_nobrl_ops = {
 	.unlocked_ioctl	= cifs_ioctl,
 #endif /* CONFIG_CIFS_POSIX */
 	.setlease = cifs_setlease,
+	.fallocate = cifs_fallocate,
 };
 
 const struct file_operations cifs_file_direct_nobrl_ops = {
@@ -1003,6 +1021,7 @@ const struct file_operations cifs_file_direct_nobrl_ops = {
 #endif /* CONFIG_CIFS_POSIX */
 	.llseek = cifs_llseek,
 	.setlease = cifs_setlease,
+	.fallocate = cifs_fallocate,
 };
 
 const struct file_operations cifs_dir_ops = {

fs/cifs/cifsglob.h

@@ -411,6 +411,8 @@ struct smb_version_operations {
 				unsigned int *, unsigned int *);
 	/* check if we need to issue closedir */
 	bool (*dir_needs_close)(struct cifsFileInfo *);
+	long (*fallocate)(struct file *, struct cifs_tcon *, int, loff_t,
+			  loff_t);
 };
 
 struct smb_version_values {

fs/cifs/smb2ops.c

@@ -1015,6 +1015,50 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 	return rc;
 }
 
+static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon,
+			    loff_t offset, loff_t len)
+{
+	struct inode *inode;
+	struct cifsInodeInfo *cifsi;
+	struct cifsFileInfo *cfile = file->private_data;
+	struct file_zero_data_information fsctl_buf;
+	long rc;
+	unsigned int xid;
+	__u8 set_sparse = 1;
+
+	xid = get_xid();
+
+	inode = cfile->dentry->d_inode;
+	cifsi = CIFS_I(inode);
+
+	/* Need to make file sparse, if not already, before freeing range. */
+	/* Consider adding equivalent for compressed since it could also work */
+	if (!smb2_set_sparse(xid, tcon, cfile, inode, set_sparse))
+		return -EOPNOTSUPP;
+
+	cifs_dbg(FYI, "offset %lld len %lld", offset, len);
+
+	fsctl_buf.FileOffset = cpu_to_le64(offset);
+	fsctl_buf.BeyondFinalZero = cpu_to_le64(offset + len);
+
+	rc = SMB2_ioctl(xid, tcon, cfile->fid.persistent_fid,
+			cfile->fid.volatile_fid, FSCTL_SET_ZERO_DATA,
+			true /* is_fctl */, (char *)&fsctl_buf,
+			sizeof(struct file_zero_data_information), NULL, NULL);
+	free_xid(xid);
+	return rc;
+}
+
+static long smb3_fallocate(struct file *file, struct cifs_tcon *tcon, int mode,
+			   loff_t off, loff_t len)
+{
+	/* KEEP_SIZE already checked for by do_fallocate */
+	if (mode & FALLOC_FL_PUNCH_HOLE)
+		return smb3_punch_hole(file, tcon, off, len);
+
+	return -EOPNOTSUPP;
+}
+
 static void
 smb2_downgrade_oplock(struct TCP_Server_Info *server,
 			struct cifsInodeInfo *cinode, bool set_level2)
@@ -1463,6 +1507,7 @@ struct smb_version_operations smb30_operations = {
 	.validate_negotiate = smb3_validate_negotiate,
 	.wp_retry_size = smb2_wp_retry_size,
 	.dir_needs_close = smb2_dir_needs_close,
+	.fallocate = smb3_fallocate,
 };
 
 struct smb_version_values smb20_values = {

fs/cifs/smb2pdu.h

@@ -573,6 +573,12 @@ struct copychunk_ioctl {
 	__u32 Reserved2;
 } __packed;
 
+/* this goes in the ioctl buffer when doing FSCTL_SET_ZERO_DATA */
+struct file_zero_data_information {
+	__le64	FileOffset;
+	__le64	BeyondFinalZero;
+} __packed;
+
 struct copychunk_ioctl_rsp {
 	__le32 ChunksWritten;
 	__le32 ChunkBytesWritten;

fs/cifs/smbfsctl.h

@@ -63,7 +63,7 @@
 #define FSCTL_SET_OBJECT_ID_EXTENDED 0x000900BC /* BB add struct */
 #define FSCTL_CREATE_OR_GET_OBJECT_ID 0x000900C0 /* BB add struct */
 #define FSCTL_SET_SPARSE             0x000900C4 /* BB add struct */
-#define FSCTL_SET_ZERO_DATA          0x000900C8 /* BB add struct */
+#define FSCTL_SET_ZERO_DATA          0x000980C8
 #define FSCTL_SET_ENCRYPTION         0x000900D7 /* BB add struct */
 #define FSCTL_ENCRYPTION_FSCTL_IO    0x000900DB /* BB add struct */
 #define FSCTL_WRITE_RAW_ENCRYPTED    0x000900DF /* BB add struct */