c5c9cd4d1b
This patch adds an additional CLONE_RANGE ioctl to clone an arbitrary
(block-aligned) file range to another file. The original CLONE ioctl
becomes a special case of cloning the entire file range. The logic is a
bit more complex now since ranges may be cloned to different offsets, and
because we may only be cloning the beginning or end of a particular extent
or checksum item.
An additional sanity check ensures the source and destination files aren't
the same (which would previously deadlock), although eventually this could
be extended to allow the duplication of file data at a different offset
within the same file.
Any extents within the destination range in the target file are dropped.
We currently do not cope with the case where a compressed inline extent
needs to be split. This will probably require decompressing the extent
into a temporary address_space, and inserting just the cloned portion as a
new compressed inline extent. For now, just return -EINVAL in this case.
Note that this never comes up in the more common case of cloning an entire
file.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
65 lines
2.1 KiB
C
65 lines
2.1 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __IOCTL_
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#define __IOCTL_
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#include <linux/ioctl.h>
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#define BTRFS_IOCTL_MAGIC 0x94
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#define BTRFS_VOL_NAME_MAX 255
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#define BTRFS_PATH_NAME_MAX 4095
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struct btrfs_ioctl_vol_args {
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char name[BTRFS_PATH_NAME_MAX + 1];
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};
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#define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
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struct btrfs_ioctl_vol_args)
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#define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
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struct btrfs_ioctl_vol_args)
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#define BTRFS_IOC_RESIZE _IOW(BTRFS_IOCTL_MAGIC, 3, \
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struct btrfs_ioctl_vol_args)
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#define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, \
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struct btrfs_ioctl_vol_args)
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/* trans start and trans end are dangerous, and only for
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* use by applications that know how to avoid the
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* resulting deadlocks
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*/
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#define BTRFS_IOC_TRANS_START _IO(BTRFS_IOCTL_MAGIC, 6)
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#define BTRFS_IOC_TRANS_END _IO(BTRFS_IOCTL_MAGIC, 7)
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#define BTRFS_IOC_SYNC _IO(BTRFS_IOCTL_MAGIC, 8)
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#define BTRFS_IOC_CLONE _IOW(BTRFS_IOCTL_MAGIC, 9, int)
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#define BTRFS_IOC_ADD_DEV _IOW(BTRFS_IOCTL_MAGIC, 10, \
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struct btrfs_ioctl_vol_args)
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#define BTRFS_IOC_RM_DEV _IOW(BTRFS_IOCTL_MAGIC, 11, \
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struct btrfs_ioctl_vol_args)
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#define BTRFS_IOC_BALANCE _IOW(BTRFS_IOCTL_MAGIC, 12, \
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struct btrfs_ioctl_vol_args)
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struct btrfs_ioctl_clone_range_args {
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__s64 src_fd;
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__u64 src_offset, src_length;
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__u64 dest_offset;
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};
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#define BTRFS_IOC_CLONE_RANGE _IOW(BTRFS_IOCTL_MAGIC, 13, \
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struct btrfs_ioctl_clone_range_args)
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#endif
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