ext4: speed up truncate/unlink by not using bforget() unless needed
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
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrey Sidorov <qrxd43@motorola.com>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index cc6d2b9..a510917 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2318,10 +2318,13 @@
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