Re: Feature Request for cp(1) utility, consider Btrfs ioctl clone range (original) (raw)

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From: Jeff liu
Subject: Re: Feature Request for cp(1) utility, consider Btrfs ioctl clone range support
Date: Fri, 19 Aug 2011 22:32:24 +0800

btw, I have posted a patch to make cp --reflink option works for OCFS2 too, http://lists.gnu.org/archive/html/coreutils/2011-05/msg00017.html

Is it acceptable?

Thanks, -Jeff

Hi Pádraig,

Thanks for your comments!

> On 08/10/2011 10:31 AM, Jeff Liu wrote: >> Hello, >> >> I just found a cool feature in Btrfs for cloning partially source file >> to the destination by specifying the desired offset and length to be copied. >> >> The call interface is something like below: >> struct btrfsclonerangeargs cr; >> cr.srcfd = sourcedesc; >> cr.srcoffset = (uint64t) offset; >> cr.srclength = (uint64t) length; >> cr.destoffset = (uint64t) doffset; >> ioctl(destfd, BTRFSIOCCLONERANGE, &args); >> >> cp(1) has already works with "reflink" supported for a long time, IMHO, >> this new feature could improve it to some extent. >> Is it acceptable to add a new option like >> "--reflink-range=srcoffset,srclength,dstoffset" to clone partially >> source file? >> In this way, if reflink-range is triggered, cp(1) will try to parse the >> offset and length which are separated by comma, >> then try to clone srclength bytes from srcoffset to the destination >> file started at dstoffset. >> if reflink-range failed, just let cp(1) fail with appropriate error info. >> >> I'd like to implement it if you guys think it does make sense. :-P. > > IMHO I don't think this level of control is needed in cp.

If you think it became useful to other coreutils stuff in the future, please let me know, I would like to work on it.

Regards, -Jeff > > cheers, > Pádraig.