From: Zhang Yi Since we have deferred the split of the unwritten extent until after I/O completion, it is not necessary to initiate the journal handle when submitting the I/O. This can improve the write performance of concurrent DIO for multiple files. The fio tests below show a ~25% performance improvement when wirting to unwritten files on my VM with a mem disk. [unwritten] direct=1 ioengine=psync numjobs=16 rw=write # write/randwrite bs=4K iodepth=1 directory=/mnt size=5G runtime=30s overwrite=0 norandommap=1 fallocate=native ramp_time=5s group_reporting=1 [w/o] w: IOPS=62.5k, BW=244MiB/s rw: IOPS=56.7k, BW=221MiB/s [w] w: IOPS=79.6k, BW=311MiB/s rw: IOPS=70.2k, BW=274MiB/s Signed-off-by: Zhang Yi --- fs/ext4/file.c | 4 +--- fs/ext4/inode.c | 4 +++- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 7a8b30932189..9f571acc7782 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -418,9 +418,7 @@ static const struct iomap_dio_ops ext4_dio_write_ops = { * updating inode i_disksize and/or orphan handling with exclusive lock. * * - shared locking will only be true mostly with overwrites, including - * initialized blocks and unwritten blocks. For overwrite unwritten blocks - * we protect splitting extents by i_data_sem in ext4_inode_info, so we can - * also release exclusive i_rwsem lock. + * initialized blocks and unwritten blocks. * * - Otherwise we will switch to exclusive i_rwsem lock. */ diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index ffde24ff7347..08a296122fe0 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3819,7 +3819,9 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, * For atomic writes the entire requested length should * be mapped. */ - if (map.m_flags & EXT4_MAP_MAPPED) { + if ((map.m_flags & EXT4_MAP_MAPPED) || + (!(flags & IOMAP_DAX) && + (map.m_flags & EXT4_MAP_UNWRITTEN))) { if ((!(flags & IOMAP_ATOMIC) && ret > 0) || (flags & IOMAP_ATOMIC && ret >= orig_mlen)) goto out; -- 2.46.1