Do not iterate over data blocks scanning for bh's to forget as they're never exist. This improves time taken by unlink / truncate syscall. Tested by continuously truncating file that is being written by dd. Another test is rm -rf of linux tree while tar unpacks it. With ordered data mode condition unlikely(!tbh) was always met in ext4_free_blocks. With journal data mode tbh was found only few times, so optimisation is also possible. Unlinking fallocated 60G file after doing sync && echo 3 > /proc/sys/vm/drop_caches && time rm --help X86 before (linux 3.6-rc4): # time rm -f test1 real 0m2.710s user 0m0.000s sys 0m1.530s X86 after: # time rm -f test1 real 0m0.644s user 0m0.003s sys 0m0.060s MIPS before (linux 2.6.37): # time rm -f test1 real 0m 4.93s user 0m 0.00s sys 0m 4.61s MIPS after: # time rm -f test1 real 0m 0.16s user 0m 0.00s sys 0m 0.06s --- fs/ext4/extents.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) Index: linux-3.6-rc6/fs/ext4/extents.c =================================================================== --- linux-3.6-rc6.orig/fs/ext4/extents.c 2012-09-17 12:08:48.842901966 -0400 +++ linux-3.6-rc6/fs/ext4/extents.c 2012-09-17 12:09:43.403630792 -0400 @@ -2274,10 +2274,13 @@ static int ext4_remove_blocks(handle_t * struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); unsigned short ee_len = ext4_ext_get_actual_len(ex); ext4_fsblk_t pblk; - int flags = EXT4_FREE_BLOCKS_FORGET; + int flags = 0; if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) - flags |= EXT4_FREE_BLOCKS_METADATA; + flags |= EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET; + else if (ext4_should_journal_data(inode)) + flags |= EXT4_FREE_BLOCKS_FORGET; + /* * For bigalloc file systems, we never free a partial cluster * at the beginning of the extent. Instead, we make a note -- 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
