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Date: Fri, 18 Jul 2014 17:50:55 +0900 From: Namjae Jeon <namjae.jeon@...sung.com> To: 'Dmitry Monakhov' <dmonakhov@...nvz.org> Cc: 'Dave Chinner' <david@...morbit.com>, 'Theodore Ts'o' <tytso@....edu>, 'linux-ext4' <linux-ext4@...r.kernel.org>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 'Brian Foster' <bfoster@...hat.com>, 'Christoph Hellwig' <hch@...radead.org>, 'Ashish Sangwan' <a.sangwan@...sung.com>, xfs@....sgi.com, 'Lukáš Czerner' <lczerner@...hat.com> Subject: RE: [PATCH 3/3] ext4: Add support IOC_MOV_DATA ioctl > On Tue, 8 Jul 2014 16:02:28 +0200 (CEST), Lukáš Czerner <lczerner@...hat.com> wrote: > Non-text part: MULTIPART/MIXED > > On Tue, 8 Jul 2014, Namjae Jeon wrote: > > > > > Date: Tue, 08 Jul 2014 21:00:02 +0900 > > > From: Namjae Jeon <namjae.jeon@...sung.com> > > > To: Dave Chinner <david@...morbit.com>, Theodore Ts'o <tytso@....edu> > > > Cc: linux-ext4 <linux-ext4@...r.kernel.org>, linux-fsdevel@...r.kernel.org, > > > linux-kernel@...r.kernel.org, Lukáš Czerner <lczerner@...hat.com>, > > > Brian Foster <bfoster@...hat.com>, Christoph Hellwig <hch@...radead.org>, > > > Ashish Sangwan <a.sangwan@...sung.com>, xfs@....sgi.com > > > Subject: [PATCH 3/3] ext4: Add support IOC_MOV_DATA ioctl > > > > > > This patch implements fs ioctl's IOC_MOV_DATA for Ext4. > > > > Hmm isn't this basically what ext4_move_extents() does ? eg. > > EXT4_IOC_MOVE_EXT ? > > > > I guess that the intention here is to do the move, without actually > > moving the data right ? But nevertheless maybe some code can be > > shared with ext4_move_extents() ? > It definitely can be shared, because it has specific case for unwritten > data see move_extent_per_page(). If I understand correctly, mov_extent_per_page calls mext_replace_branches to _replace_ extents from 1 inode to other inode. Please correct me if I am wrong. ioc_mov_data will not replace extents, but it will actually _move_ extents into hole from donor to receiver, leaving a hole at the place from where extents are moved. Could you elaborate more how it can be shared for unwritten data case ? > But I think we can observe another way to unify this two things. > An idea inspired by the fact that ioc_move_data works only for > regular inodes, where orig_offset == donor_offset. Could you elaborate this point? > This is showstopper > for my utility e4defrag2 ( new version of e4defrag which is able defragment > pack small files as described here : > http://lists.openwall.net/linux-ext4/2014/04/28/3) > > Proposed API is very similar to ext4_ext_migrate: > Args: > orig_file: inode which we want to defragment > donor_file: a file which will be used as a donor of blocks > 1) fallocate big donor_file > 2) a) Create tmp inode wich nlink = 0 > b) move extents required extents from donor to tmp_donor_inode > c) return file descriptor (tmp_fd) to that tmp_donor_inode > 4) Mark orig_file's inode with EXT4_STATE_EXT_MIGRATE state > 5) Copy data from orig_file to tmp_fd > 6) IOC_SWAP_EX: atomically swap orig_file->i_data and tmp_fd->i_data > if EXT4_STATE_EXT_MIGRATE was not cleared. > > This approach can works not only for regular file w/o journaling > enabled, but also for journaled ones, and directories. > > > > > > > > -Lukas > > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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