Commit e9f53353 authored by Daejun Park's avatar Daejun Park Committed by Theodore Ts'o
Browse files

ext4: remove expensive flush on fast commit 



In the fast commit, it adds REQ_FUA and REQ_PREFLUSH on each fast
commit block when barrier is enabled.  However, in recovery phase,
ext4 compares CRC value in the tail.  So it is sufficient to add
REQ_FUA and REQ_PREFLUSH on the block that has tail.

Signed-off-by: default avatarDaejun Park <daejun7.park@samsung.com>
Reviewed-by: default avatarHarshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20210106013242epcms2p5b6b4ed8ca86f29456fdf56aa580e74b4@epcms2p5


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 6b4b8e6b

fs/ext4/fast_commit.c

+5 −5
Original line number Diff line number Diff line
@@ -604,13 +604,13 @@ void ext4_fc_track_range(handle_t *handle, struct inode *inode, ext4_lblk_t star 
	trace_ext4_fc_track_range(inode, start, end, ret);

}



static void ext4_fc_submit_bh(struct super_block *sb)

static void ext4_fc_submit_bh(struct super_block *sb, bool is_tail)

{

	int write_flags = REQ_SYNC;

	struct buffer_head *bh = EXT4_SB(sb)->s_fc_bh;



	/* TODO: REQ_FUA | REQ_PREFLUSH is unnecessarily expensive. */

	if (test_opt(sb, BARRIER))

	/* Add REQ_FUA | REQ_PREFLUSH only its tail */

	if (test_opt(sb, BARRIER) && is_tail)

		write_flags |= REQ_FUA | REQ_PREFLUSH;

	lock_buffer(bh);

	set_buffer_dirty(bh);
@@ -684,7 +684,7 @@ static u8 *ext4_fc_reserve_space(struct super_block *sb, int len, u32 *crc) 
		*crc = ext4_chksum(sbi, *crc, tl, sizeof(*tl));

	if (pad_len > 0)

		ext4_fc_memzero(sb, tl + 1, pad_len, crc);

	ext4_fc_submit_bh(sb);

	ext4_fc_submit_bh(sb, false);



	ret = jbd2_fc_get_buf(EXT4_SB(sb)->s_journal, &bh);

	if (ret)
@@ -741,7 +741,7 @@ static int ext4_fc_write_tail(struct super_block *sb, u32 crc) 
	tail.fc_crc = cpu_to_le32(crc);

	ext4_fc_memcpy(sb, dst, &tail.fc_crc, sizeof(tail.fc_crc), NULL);



	ext4_fc_submit_bh(sb);

	ext4_fc_submit_bh(sb, true);



	return 0;

}