From: "Manish Katiyar" Subject: Re: Copying Data Blocks Date: Tue, 6 Jan 2009 22:58:13 +0530 Message-ID: References: <2d08ef090901060236p46d4d396x797e4bceb24a2a34@mail.gmail.com> <5feb302e0901060612p4e114953pb6e297778aa7c0a4@mail.gmail.com> <2d08ef090901060845t85ac2b0i11c684a09d930608@mail.gmail.com> <2d08ef090901060916y4c49884dy4b44d6354b11ebb8@mail.gmail.com> <2d08ef090901060925p685506abkdc722c4099b485c7@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "rishi agrawal" , ext4 , Kernelnewbies To: "Rohit Sharma" Return-path: Received: from ti-out-0910.google.com ([209.85.142.191]:9479 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751403AbZAFR2P (ORCPT ); Tue, 6 Jan 2009 12:28:15 -0500 Received: by ti-out-0910.google.com with SMTP id b6so9866024tic.23 for ; Tue, 06 Jan 2009 09:28:13 -0800 (PST) In-Reply-To: <2d08ef090901060925p685506abkdc722c4099b485c7@mail.gmail.com> Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jan 6, 2009 at 10:55 PM, Rohit Sharma wrote: > We can find out no. of block currently being used by the donor inode, > The data we read from donor inode has to be in some buffer or page, Since we know the blocknumber of donor inode, it should be possible to do a raw read and get the memory address of the data page using sb_bread() and then accessing bh->b_data . Isn't it ? Thanks - Manish > is there a way we can associate this buffer with the reciever inode > or write the contents of the buffer to the new inode. > > > On Tue, Jan 6, 2009 at 10:46 PM, Rohit Sharma wrote: >> On Tue, Jan 6, 2009 at 10:43 PM, Manish Katiyar wrote: >>> On Tue, Jan 6, 2009 at 10:15 PM, Rohit Sharma wrote: >>>> On Tue, Jan 6, 2009 at 7:42 PM, rishi agrawal wrote: >>>>> yes i suppose the donor inode is known >>>>> moreover the receiver inode's number is also known >>>>> >>>>> On Tue, Jan 6, 2009 at 6:54 PM, Manish Katiyar wrote: >>>>>> >>>>>> On Tue, Jan 6, 2009 at 4:06 PM, Rohit Sharma wrote: >>>>>> > I want to read data blocks from one inode >>>>>> > and copy it to other inode. >>>>>> > >>>>>> > I mean to copy data from data blocks associated with one inode >>>>>> > to the data blocks associated with other inode. >>>>>> >>>>>> Copying 4K chunk of data itself is a costly operation. and depending >>>> >>>> Yes its a costly operation, but if this can be done then >>>> we can definitely copy n blocks at a time. >>>> >>>>>> on the size of your donor inode this can be huge . Why do you want to >>>>>> do that ? Do you know the inode of the donor inode ? >>>> >>>> For physically relocating a file from one disk to other. >>>> >>>> Yes Manish, i know the donor inode and i will create the reciever inode. >>> >>> I am guessing .......will something like this work ? >>> >>> ino_t donor_inode_num; >>> struct inode *donor_inode = FS_iget(sb , donor_inode_num); >>> struct FS_inode_info * fsi = FSI(donor_inode) ; // Do the regular >>> container_of stuff here >>> >>> for ( i = 0; i < (donor_inode->i_size + sb->s_blocksize - >>> 1)/sb->s_blocksize ; i ++ ) { >>> // Do a memmove or memcpy here from fsi->i_data[i] >>> } >>> >>> I am not sure though how will you prevent the donor inode from being >>> changed/resized during this period. >> >> I am thinking of remounting ext2 in readonly mode, or i'll change the >> mount flags to readonly. But i m not sure if internally i can copy the >> data from one block to other. >> >>> >>> Thanks - >>> Manish >>> >>> >>>> >>>> Can we do that in kernel space.? >>>>>> >>>>>> thanks - >>>>>> Manish >>>>>> > >>>>>> > Is that possible in kernel space.? >>>>>> > -- >>>>>> > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >>>>>> > the body of a message to majordomo@vger.kernel.org >>>>>> > More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>>> > >>>>>> -- >>>>>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >>>>>> the body of a message to majordomo@vger.kernel.org >>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>> >>>>> >>>>> >>>>> -- >>>>> Regards, >>>>> Rishi B. Agrawal >>>>> >>>>> >>>> >>> >> >