Introduce cifs_copy_file_range()

The earlier changes to copy range for cifs unintentionally disabled the more
common form of server side copy.

The patch introduces the file_operations helper cifs_copy_file_range()
which is used by the syscall copy_file_range. The new file operations
helper allows us to perform server side copies for SMB2.0 and 2.1
servers as well as SMB 3.0+ servers which do not support the ioctl
FSCTL_DUPLICATE_EXTENTS_TO_FILE.

The new helper uses the ioctl FSCTL_SRV_COPYCHUNK_WRITE to perform
server side copies. The helper is called by vfs_copy_file_range() only
once an attempt to clone the file using the ioctl
FSCTL_DUPLICATE_EXTENTS_TO_FILE has failed.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
CC: Stable  <stable@vger.kernel.org>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 87 insertions, 0 deletions

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 15e1db8738ae..dd3f5fabfdf6 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -972,6 +972,86 @@ out:
 	return rc;
 }
 
+ssize_t cifs_file_copychunk_range(unsigned int xid,
+				struct file *src_file, loff_t off,
+				struct file *dst_file, loff_t destoff,
+				size_t len, unsigned int flags)
+{
+	struct inode *src_inode = file_inode(src_file);
+	struct inode *target_inode = file_inode(dst_file);
+	struct cifsFileInfo *smb_file_src;
+	struct cifsFileInfo *smb_file_target;
+	struct cifs_tcon *src_tcon;
+	struct cifs_tcon *target_tcon;
+	ssize_t rc;
+
+	cifs_dbg(FYI, "copychunk range\n");
+
+	if (src_inode == target_inode) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	if (!src_file->private_data || !dst_file->private_data) {
+		rc = -EBADF;
+		cifs_dbg(VFS, "missing cifsFileInfo on copy range src file\n");
+		goto out;
+	}
+
+	rc = -EXDEV;
+	smb_file_target = dst_file->private_data;
+	smb_file_src = src_file->private_data;
+	src_tcon = tlink_tcon(smb_file_src->tlink);
+	target_tcon = tlink_tcon(smb_file_target->tlink);
+
+	if (src_tcon->ses != target_tcon->ses) {
+		cifs_dbg(VFS, "source and target of copy not on same server\n");
+		goto out;
+	}
+
+	/*
+	 * Note: cifs case is easier than btrfs since server responsible for
+	 * checks for proper open modes and file type and if it wants
+	 * server could even support copy of range where source = target
+	 */
+	lock_two_nondirectories(target_inode, src_inode);
+
+	cifs_dbg(FYI, "about to flush pages\n");
+	/* should we flush first and last page first */
+	truncate_inode_pages(&target_inode->i_data, 0);
+
+	if (target_tcon->ses->server->ops->copychunk_range)
+		rc = target_tcon->ses->server->ops->copychunk_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
+	 */
+	CIFS_I(target_inode)->time = 0;
+	/* although unlocking in the reverse order from locking is not
+	 * strictly necessary here it is a little cleaner to be consistent
+	 */
+	unlock_two_nondirectories(src_inode, target_inode);
+
+out:
+	return rc;
+}
+
+static ssize_t cifs_copy_file_range(struct file *src_file, loff_t off,
+				struct file *dst_file, loff_t destoff,
+				size_t len, unsigned int flags)
+{
+	unsigned int xid = get_xid();
+	ssize_t rc;
+
+	rc = cifs_file_copychunk_range(xid, src_file, off, dst_file, destoff,
+					len, flags);
+	free_xid(xid);
+	return rc;
+}
+
 const struct file_operations cifs_file_ops = {
 	.read_iter = cifs_loose_read_iter,
 	.write_iter = cifs_file_write_iter,
@@ -984,6 +1064,7 @@ const struct file_operations cifs_file_ops = {
 	.splice_read = generic_file_splice_read,
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
+	.copy_file_range = cifs_copy_file_range,
 	.clone_file_range = cifs_clone_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
@@ -1001,6 +1082,7 @@ const struct file_operations cifs_file_strict_ops = {
 	.splice_read = generic_file_splice_read,
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
+	.copy_file_range = cifs_copy_file_range,
 	.clone_file_range = cifs_clone_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
@@ -1018,6 +1100,7 @@ const struct file_operations cifs_file_direct_ops = {
 	.mmap = cifs_file_mmap,
 	.splice_read = generic_file_splice_read,
 	.unlocked_ioctl  = cifs_ioctl,
+	.copy_file_range = cifs_copy_file_range,
 	.clone_file_range = cifs_clone_file_range,
 	.llseek = cifs_llseek,
 	.setlease = cifs_setlease,
@@ -1035,6 +1118,7 @@ const struct file_operations cifs_file_nobrl_ops = {
 	.splice_read = generic_file_splice_read,
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
+	.copy_file_range = cifs_copy_file_range,
 	.clone_file_range = cifs_clone_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
@@ -1051,6 +1135,7 @@ const struct file_operations cifs_file_strict_nobrl_ops = {
 	.splice_read = generic_file_splice_read,
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
+	.copy_file_range = cifs_copy_file_range,
 	.clone_file_range = cifs_clone_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
@@ -1067,6 +1152,7 @@ const struct file_operations cifs_file_direct_nobrl_ops = {
 	.mmap = cifs_file_mmap,
 	.splice_read = generic_file_splice_read,
 	.unlocked_ioctl  = cifs_ioctl,
+	.copy_file_range = cifs_copy_file_range,
 	.clone_file_range = cifs_clone_file_range,
 	.llseek = cifs_llseek,
 	.setlease = cifs_setlease,
@@ -1078,6 +1164,7 @@ const struct file_operations cifs_dir_ops = {
 	.release = cifs_closedir,
 	.read    = generic_read_dir,
 	.unlocked_ioctl  = cifs_ioctl,
+	.copy_file_range = cifs_copy_file_range,
 	.clone_file_range = cifs_clone_file_range,
 	.llseek = generic_file_llseek,
 };