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linux-next/fs/cifs/ioctl.c
Steve French f19e84df37 [CIFS] Do not use btrfs refcopy ioctl for SMB2 copy offload 
Change cifs.ko to using CIFS_IOCTL_COPYCHUNK instead
of BTRFS_IOC_CLONE to avoid confusion about whether
copy-on-write is required or optional for this operation.

SMB2/SMB3 copyoffload had used the BTRFS_IOC_CLONE ioctl since
they both speed up copy by offloading the copy rather than
passing many read and write requests back and forth and both have
identical syntax (passing file handles), but for SMB2/SMB3
CopyChunk the server is not required to use copy-on-write
to make a copy of the file (although some do), and Christoph
has commented that since CopyChunk does not require
copy-on-write we should not reuse BTRFS_IOC_CLONE.

This patch renames the ioctl to use a cifs specific IOCTL
CIFS_IOCTL_COPYCHUNK.  This ioctl is particularly important
for SMB2/SMB3 since large file copy over the network otherwise
can be very slow, and with this is often more than 100 times
faster putting less load on server and client.

Note that if a copy syscall is ever introduced, depending on
its requirements/format it could end up using one of the other
three methods that CIFS/SMB2/SMB3 can do for copy offload,
but this method is particularly useful for file copy
and broadly supported (not just by Samba server).

Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: David Disseldorp <ddiss@samba.org>
2013-11-25 09:50:31 -06:00

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/*
* fs/cifs/ioctl.c
*
* vfs operations that deal with io control
*
* Copyright (C) International Business Machines Corp., 2005,2013
* Author(s): Steve French (sfrench@us.ibm.com)
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifsfs.h"
#define CIFS_IOCTL_MAGIC 0xCF
#define CIFS_IOC_COPYCHUNK_FILE _IOW(CIFS_IOCTL_MAGIC, 3, int)
static long cifs_ioctl_clone(unsigned int xid, struct file *dst_file,
unsigned long srcfd, u64 off, u64 len, u64 destoff)
{
int rc;
struct cifsFileInfo *smb_file_target = dst_file->private_data;
struct inode *target_inode = file_inode(dst_file);
struct cifs_tcon *target_tcon;
struct fd src_file;
struct cifsFileInfo *smb_file_src;
struct inode *src_inode;
struct cifs_tcon *src_tcon;
cifs_dbg(FYI, "ioctl clone range\n");
/* the destination must be opened for writing */
if (!(dst_file->f_mode & FMODE_WRITE)) {
cifs_dbg(FYI, "file target not open for write\n");
return -EINVAL;
}
/* check if target volume is readonly and take reference */
rc = mnt_want_write_file(dst_file);
if (rc) {
cifs_dbg(FYI, "mnt_want_write failed with rc %d\n", rc);
return rc;
}
src_file = fdget(srcfd);
if (!src_file.file) {
rc = -EBADF;
goto out_drop_write;
}
if ((!src_file.file->private_data) || (!dst_file->private_data)) {
rc = -EBADF;
cifs_dbg(VFS, "missing cifsFileInfo on copy range src file\n");
goto out_fput;
}
rc = -EXDEV;
smb_file_target = dst_file->private_data;
smb_file_src = src_file.file->private_data;
src_tcon = tlink_tcon(smb_file_src->tlink);
target_tcon = tlink_tcon(smb_file_target->tlink);
/* check if source and target are on same tree connection */
if (src_tcon != target_tcon) {
cifs_dbg(VFS, "file copy src and target on different volume\n");
goto out_fput;
}
src_inode = src_file.file->f_dentry->d_inode;
/*
* 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
*/
/* so we do not deadlock racing two ioctls on same files */
if (target_inode < src_inode) {
mutex_lock_nested(&target_inode->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&src_inode->i_mutex, I_MUTEX_CHILD);
} else {
mutex_lock_nested(&src_inode->i_mutex, I_MUTEX_PARENT);
mutex_lock_nested(&target_inode->i_mutex, I_MUTEX_CHILD);
}
/* determine range to clone */
rc = -EINVAL;
if (off + len > src_inode->i_size || off + len < off)
goto out_unlock;
if (len == 0)
len = src_inode->i_size - off;
cifs_dbg(FYI, "about to flush pages\n");
/* should we flush first and last page first */
truncate_inode_pages_range(&target_inode->i_data, destoff,
PAGE_CACHE_ALIGN(destoff + len)-1);
if (target_tcon->ses->server->ops->clone_range)
rc = target_tcon->ses->server->ops->clone_range(xid,
smb_file_src, smb_file_target, off, len, destoff);
/* force revalidate of size and timestamps of target file now
that target is updated on the server */
CIFS_I(target_inode)->time = 0;
out_unlock:
/* although unlocking in the reverse order from locking is not
strictly necessary here it is a little cleaner to be consistent */
if (target_inode < src_inode) {
mutex_unlock(&src_inode->i_mutex);
mutex_unlock(&target_inode->i_mutex);
} else {
mutex_unlock(&target_inode->i_mutex);
mutex_unlock(&src_inode->i_mutex);
}
out_fput:
fdput(src_file);
out_drop_write:
mnt_drop_write_file(dst_file);
return rc;
}
long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
{
struct inode *inode = file_inode(filep);
int rc = -ENOTTY; /* strange error - but the precedent */
unsigned int xid;
struct cifs_sb_info *cifs_sb;
struct cifsFileInfo *pSMBFile = filep->private_data;
struct cifs_tcon *tcon;
__u64 ExtAttrBits = 0;
__u64 caps;
xid = get_xid();
cifs_dbg(FYI, "ioctl file %p cmd %u arg %lu\n", filep, command, arg);
cifs_sb = CIFS_SB(inode->i_sb);
switch (command) {
case FS_IOC_GETFLAGS:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
caps = le64_to_cpu(tcon->fsUnixInfo.Capability);
#ifdef CONFIG_CIFS_POSIX
if (CIFS_UNIX_EXTATTR_CAP & caps) {
__u64 ExtAttrMask = 0;
rc = CIFSGetExtAttr(xid, tcon,
pSMBFile->fid.netfid,
&ExtAttrBits, &ExtAttrMask);
if (rc == 0)
rc = put_user(ExtAttrBits &
FS_FL_USER_VISIBLE,
(int __user *)arg);
if (rc != EOPNOTSUPP)
break;
}
#endif /* CONFIG_CIFS_POSIX */
rc = 0;
if (CIFS_I(inode)->cifsAttrs & ATTR_COMPRESSED) {
/* add in the compressed bit */
ExtAttrBits = FS_COMPR_FL;
rc = put_user(ExtAttrBits & FS_FL_USER_VISIBLE,
(int __user *)arg);
}
break;
case FS_IOC_SETFLAGS:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
caps = le64_to_cpu(tcon->fsUnixInfo.Capability);
if (get_user(ExtAttrBits, (int __user *)arg)) {
rc = -EFAULT;
break;
}
/*
* if (CIFS_UNIX_EXTATTR_CAP & caps)
* rc = CIFSSetExtAttr(xid, tcon,
* pSMBFile->fid.netfid,
* extAttrBits,
* &ExtAttrMask);
* if (rc != EOPNOTSUPP)
* break;
*/
/* Currently only flag we can set is compressed flag */
if ((ExtAttrBits & FS_COMPR_FL) == 0)
break;
/* Try to set compress flag */
if (tcon->ses->server->ops->set_compression) {
rc = tcon->ses->server->ops->set_compression(
xid, tcon, pSMBFile);
cifs_dbg(FYI, "set compress flag rc %d\n", rc);
}
break;
case CIFS_IOC_COPYCHUNK_FILE:
rc = cifs_ioctl_clone(xid, filep, arg, 0, 0, 0);
break;
default:
cifs_dbg(FYI, "unsupported ioctl\n");
break;
}
free_xid(xid);
return rc;
}
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