[PATCH 2/2] Introduce cifs_copy_file_range()

[Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 fs/cifs/cifsfs.c   | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/cifs/cifsfs.h   |  5 ++++
 fs/cifs/cifsglob.h |  6 ++--
 fs/cifs/ioctl.c    | 60 ++-----------------------------------
 fs/cifs/smb2ops.c  | 20 ++++++++-----
 5 files changed, 110 insertions(+), 68 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 70f4e65..9e32988 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -972,6 +972,86 @@ static int cifs_clone_file_range(struct file *src_file, loff_t off,
 	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;
+}
+
+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,
 };
diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index c9c00a8..6eb8174 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -139,6 +139,11 @@ extern ssize_t	cifs_listxattr(struct dentry *, char *, size_t);
 # define cifs_listxattr NULL
 #endif
 
+extern 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);
+
 extern long cifs_ioctl(struct file *filep, unsigned int cmd, unsigned long arg);
 #ifdef CONFIG_CIFS_NFSD_EXPORT
 extern const struct export_operations cifs_export_ops;
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index f9376db..dda6d0b 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -405,10 +405,10 @@ struct smb_version_operations {
 	char * (*create_lease_buf)(u8 *, u8);
 	/* parse lease context buffer and return oplock/epoch info */
 	__u8 (*parse_lease_buf)(void *, unsigned int *);
-	int (*copychunk_range)(const unsigned int,
+	ssize_t (*copychunk_range)(const unsigned int,
 			struct cifsFileInfo *src_file,
-			struct cifsFileInfo *target_file, u64 src_off, u64 len,
-			u64 dest_off);
+			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);
diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c
index 9bf0f94..265c45f 100644
--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -34,63 +34,6 @@
 #include "cifs_ioctl.h"
 #include <linux/btrfs.h>
 
-static int cifs_file_copychunk_range(unsigned int xid, struct file *src_file,
-			  struct file *dst_file)
-{
-	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;
-	int rc;
-
-	cifs_dbg(FYI, "ioctl copychunk range\n");
-
-	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, 0, src_inode->i_size, 0);
-	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 long cifs_ioctl_copychunk(unsigned int xid, struct file *dst_file,
 			unsigned long srcfd)
 {
@@ -129,7 +72,8 @@ static long cifs_ioctl_copychunk(unsigned int xid, struct file *dst_file,
 	if (S_ISDIR(src_inode->i_mode))
 		goto out_fput;
 
-	rc = cifs_file_copychunk_range(xid, src_file.file, dst_file);
+	rc = cifs_file_copychunk_range(xid, src_file.file, 0, dst_file, 0,
+					src_inode->i_size, 0);
 
 out_fput:
 	fdput(src_file);
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 3dfd925..bf0c71d 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -586,7 +586,7 @@ SMB2_request_res_key(const unsigned int xid, struct cifs_tcon *tcon,
 	return rc;
 }
 
-static int
+static ssize_t
 smb2_copychunk_range(const unsigned int xid,
 			struct cifsFileInfo *srcfile,
 			struct cifsFileInfo *trgtfile, u64 src_off,
@@ -599,6 +599,7 @@ smb2_copychunk_range(const unsigned int xid,
 	struct cifs_tcon *tcon;
 	int chunks_copied = 0;
 	bool chunk_sizes_updated = false;
+	ssize_t bytes_written, total_bytes_written = 0;
 
 	pcchunk = kmalloc(sizeof(struct copychunk_ioctl), GFP_KERNEL);
 
@@ -662,14 +663,16 @@ smb2_copychunk_range(const unsigned int xid,
 			}
 			chunks_copied++;
 
-			src_off += le32_to_cpu(retbuf->TotalBytesWritten);
-			dest_off += le32_to_cpu(retbuf->TotalBytesWritten);
-			len -= le32_to_cpu(retbuf->TotalBytesWritten);
+			bytes_written = le32_to_cpu(retbuf->TotalBytesWritten);
+			src_off += bytes_written;
+			dest_off += bytes_written;
+			len -= bytes_written;
+			total_bytes_written += bytes_written;
 
-			cifs_dbg(FYI, "Chunks %d PartialChunk %d Total %d\n",
+			cifs_dbg(FYI, "Chunks %d PartialChunk %d Total %zu\n",
 				le32_to_cpu(retbuf->ChunksWritten),
 				le32_to_cpu(retbuf->ChunkBytesWritten),
-				le32_to_cpu(retbuf->TotalBytesWritten));
+				bytes_written);
 		} else if (rc == -EINVAL) {
 			if (ret_data_len != sizeof(struct copychunk_ioctl_rsp))
 				goto cchunk_out;
@@ -706,7 +709,10 @@ smb2_copychunk_range(const unsigned int xid,
 cchunk_out:
 	kfree(pcchunk);
 	kfree(retbuf);
-	return rc;
+	if (rc)
+		return rc;
+	else
+		return total_bytes_written;
 }
 
 static int
-- 
2.9.3