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: Daejun Park <daejun7.park@samsung.com>
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20210106013242epcms2p5b6b4ed8ca86f29456fdf56aa580e74b4@epcms2p5
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
(cherry picked from commit e9f53353e166a67dfe4f8295100f8ac39d6cf10b)
Change-Id: I4cd2df3c419059fc98dcc4c7e97c297749073d1c
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/10969
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Harshad Shirwadkar <harshads@google.com>
diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 2ffee73..fd74faa 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -604,13 +604,13 @@
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 @@
*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 @@
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;
}
