[PATCH 1/2 v2] exfat: write multiple sectors at once

[Tetsuhiro Kohada <kohada.t2@gmail.com>]

Write multiple sectors at once when updating dir-entries.
Add exfat_update_bhs() for that. It wait for write completion once
instead of sector by sector.
It's only effective if sync enabled.

Suggested-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Tetsuhiro Kohada <kohada.t2@gmail.com>
---
Changes in v2:
 - Split into 'write multiple sectors at once'
   and 'add error check when updating dir-entries'

 fs/exfat/dir.c      | 12 +++++++-----
 fs/exfat/exfat_fs.h |  1 +
 fs/exfat/misc.c     | 19 +++++++++++++++++++
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index de43534aa299..495884ccb352 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -604,13 +604,15 @@ void exfat_update_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es)
 
 void exfat_free_dentry_set(struct exfat_entry_set_cache *es, int sync)
 {
-	int i;
+	int i, err = 0;
 
-	for (i = 0; i < es->num_bh; i++) {
-		if (es->modified)
-			exfat_update_bh(es->sb, es->bh[i], sync);
-		brelse(es->bh[i]);
+	if (es->modified) {
+		set_bit(EXFAT_SB_DIRTY, &EXFAT_SB(es->sb)->s_state);
+		err = exfat_update_bhs(es->bh, es->num_bh, sync);
 	}
+
+	for (i = 0; i < es->num_bh; i++)
+		err ? bforget(es->bh[i]):brelse(es->bh[i]);
 	kfree(es);
 }
 
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 595f3117f492..935954da2e54 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -515,6 +515,7 @@ void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
 u16 exfat_calc_chksum16(void *data, int len, u16 chksum, int type);
 u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type);
 void exfat_update_bh(struct super_block *sb, struct buffer_head *bh, int sync);
+int exfat_update_bhs(struct buffer_head **bhs, int nr_bhs, int sync);
 void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,
 		unsigned int size, unsigned char flags);
 void exfat_chain_dup(struct exfat_chain *dup, struct exfat_chain *ec);
diff --git a/fs/exfat/misc.c b/fs/exfat/misc.c
index 17d41f3d3709..dc34968e99d3 100644
--- a/fs/exfat/misc.c
+++ b/fs/exfat/misc.c
@@ -173,6 +173,25 @@ void exfat_update_bh(struct super_block *sb, struct buffer_head *bh, int sync)
 		sync_dirty_buffer(bh);
 }
 
+int exfat_update_bhs(struct buffer_head **bhs, int nr_bhs, int sync)
+{
+	int i, err = 0;
+
+	for (i = 0; i < nr_bhs; i++) {
+		set_buffer_uptodate(bhs[i]);
+		mark_buffer_dirty(bhs[i]);
+		if (sync)
+			write_dirty_buffer(bhs[i], 0);
+	}
+
+	for (i = 0; i < nr_bhs && sync; i++) {
+		wait_on_buffer(bhs[i]);
+		if (!buffer_uptodate(bhs[i]))
+			err = -EIO;
+	}
+	return err;
+}
+
 void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,
 		unsigned int size, unsigned char flags)
 {
-- 
2.25.1