from small one page howto to huge articles all in one place
 

search text in:





Poll
Which linux distribution do you use?







poll results

Last additions:
using iotop to find disk usage hogs

using iotop to find disk usage hogs

words:

887

views:

125167

userrating:

average rating: 1.7 (86 votes) (1=very good 6=terrible)


May 25th. 2007:
Words

486

Views

235581

why adblockers are bad


Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

words:

161

views:

116218

userrating:

average rating: 1.3 (28 votes) (1=very good 6=terrible)


April, 26th. 2006:

Druckversion
You are here: manpages





IOCTL-FICLONERANGE

Section: Linux Programmer's Manual (2)
Updated: 2017-09-15
Index Return to Main Contents
 

NAME

ioctl_ficlonerange, ioctl_ficlone - share some the data of one file with another file  

SYNOPSIS


#include <sys/ioctl.h>
#include <linux/fs.h>

int ioctl(int dest_fd, FICLONERANGE, struct file_clone_range *arg);
int ioctl(int dest_fd, FICLONE, int src_fd);  

DESCRIPTION

If a filesystem supports files sharing physical storage between multiple files ("reflink"), this ioctl(2) operation can be used to make some of the data in the src_fd file appear in the dest_fd file by sharing the underlying storage, which is faster than making a separate physical copy of the data. Both files must reside within the same filesystem. If a file write should occur to a shared region, the filesystem must ensure that the changes remain private to the file being written. This behavior is commonly referred to as "copy on write".

This ioctl reflinks up to src_length bytes from file descriptor src_fd at offset src_offset into the file dest_fd at offset dest_offset, provided that both are files. If src_length is zero, the ioctl reflinks to the end of the source file. This information is conveyed in a structure of the following form:

struct file_clone_range {
    __s64 src_fd;
    __u64 src_offset;
    __u64 src_length;
    __u64 dest_offset; };

Clones are atomic with regards to concurrent writes, so no locks need to be taken to obtain a consistent cloned copy.

The FICLONE ioctl clones entire files.  

RETURN VALUE

On error, -1 is returned, and errno is set to indicate the error.

 

ERRORS

Error codes can be one of, but are not limited to, the following:
EBADF
src_fd is not open for reading; dest_fd is not open for writing or is open for append-only writes; or the filesystem which src_fd resides on does not support reflink.
EINVAL
The filesystem does not support reflinking the ranges of the given files. This error can also appear if either file descriptor represents a device, FIFO, or socket. Disk filesystems generally require the offset and length arguments to be aligned to the fundamental block size. XFS and Btrfs do not support overlapping reflink ranges in the same file.
EISDIR
One of the files is a directory and the filesystem does not support shared regions in directories.
EOPNOTSUPP
This can appear if the filesystem does not support reflinking either file descriptor, or if either file descriptor refers to special inodes.
EPERM
dest_fd is immutable.
ETXTBSY
One of the files is a swap file. Swap files cannot share storage.
EXDEV
dest_fd and src_fd are not on the same mounted filesystem.
 

VERSIONS

These ioctl operations first appeared in Linux 4.5. They were previously known as BTRFS_IOC_CLONE and BTRFS_IOC_CLONE_RANGE, and were private to Btrfs.  

CONFORMING TO

This API is Linux-specific.  

NOTES

Because a copy-on-write operation requires the allocation of new storage, the fallocate(2) operation may unshare shared blocks to guarantee that subsequent writes will not fail because of lack of disk space.  

SEE ALSO

ioctl(2)  

COLOPHON

This page is part of release 4.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
VERSIONS
CONFORMING TO
NOTES
SEE ALSO
COLOPHON





Other free services
toURL.org
Shorten long
URLs to short
links like
http://tourl.org/2
tourl.org
.
Reverse DNS lookup
Find out which hostname(s)
resolve to a
given IP or other hostnames for the server
www.reversednslookup.org
rdf newsfeed | rss newsfeed | Atom newsfeed
- Powered by LeopardCMS - Running on Gentoo -
Copyright 2004-2018 Sascha Nitsch Unternehmensberatung UG(haftungsbeschränkt)
Valid XHTML1.1 : Valid CSS : buttonmaker
- Level Triple-A Conformance to Web Content Accessibility Guidelines 1.0 -
- Copyright and legal notices -
Time to create this page: 3.4 ms