Hi, There are the updated patches for ext4 online defrag. I have addressed the comments that I had got about defrag V1 (http://marc.info/?l=linux-ext4&m=123329594919001&w=3). Changes of this version are as follows: - Change function name from ext4_defrag_xxx to ext4_mext_xxx and also change the source file name from defrag.c to move_extent.c. - Disallow swapfile defrag. - Support uninitialized extent defrag. - Disallow data write out for uninitalized extent. - Call fget() and fput() instead of fget_light() and fput_light() for module compile. - Acquire mutex and semaphore of orig and donor inodes by i_ino order. - Localized semaphore acquisition/release. - Add ext4_mext_inode_double_lock/unlock() for i_mutex lock/unlock, since inode_double_lock/unlock() have been removed. - Replace random printk() with ext4_debug(). - Some cleanups. Ext4 online defrag uses EXT4_IOC_MOVE_EXT ioctl and move_extent structure. #define EXT4_IOC_MOVE_EXT _IOWR('f', 15, struct move_extent) struct move_extent { int orig_fd; /* original file descriptor */ int donor_fd; /* donor file descriptor */ __u64 orig_start; /* logical start offset in block for orig */ __u64 donor_start; /* logical start offset in block for donor */ __u64 len; /* block length to be moved */ __u64 moved_len; /* moved block length */ }; Ext4 online defrag is done in the following steps: (U:User space K:Kernel space) 1:U Create donor inode and then call unlink() to it. 2:U Allocate contiguous blocks to donor inode with fallocate(). 3:U Call the FS_IOC_FIEMAP ioctl to get the extents information of donor inode. And check the extents of donor inode are less than the defrag target inode's. 4:U Call the EXT4_IOC_MOVE_EXT ioctl extent unit. 5:K In kernel space, the EXT4_IOC_MOVE_EXT ioctl calls ext4_mext_move_extent() to exchange the blocks between orig_fd and donor_fd. Then write the file data of orig_fd to donor_fd. 6:U Close donor inode, then it will be deleted. Note: More tests may be needed without journal, so I recommend that e4defrag is run on ext4 with journal. Summary of patch series: * The patch can be applied to the ext4 patch queue (2.6.30-rc6). [PATCH 1/3] Add EXT4_IOC_DEFRAG ioctl and defrag functions - Add EXT4_IOC_DEFRAG ioctl and related functions. - For each page, exchange the extents between original inode and donor inode, and then write the file data of the original inode to donor inode. [PATCH 2/3] Ext4 online defrag command - Usage is as follows: - Defrag for a single file. # e4defrag file, directory, device - Check the file fragments on ext4. # e4defrag -c file, directory, device [PATCH 3/3] Manpage of e4defrag - Ext4 online defrag command manpage # nroff -man e4defrag.8 Best regards, Akira Fujita -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
