> On Tue, 8 Jul 2014 16:02:28 +0200 (CEST), Lukáš Czerner <lczerner@xxxxxxxxxx> 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@xxxxxxxxxxx> > > > To: Dave Chinner <david@xxxxxxxxxxxxx>, Theodore Ts'o <tytso@xxxxxxx> > > > Cc: linux-ext4 <linux-ext4@xxxxxxxxxxxxxxx>, linux-fsdevel@xxxxxxxxxxxxxxx, > > > linux-kernel@xxxxxxxxxxxxxxx, Lukáš Czerner <lczerner@xxxxxxxxxx>, > > > Brian Foster <bfoster@xxxxxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, > > > Ashish Sangwan <a.sangwan@xxxxxxxxxxx>, xfs@xxxxxxxxxxx > > > 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-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
