[PATCH 1/2 v4] exfat: write multiple sectors at once

[Tetsuhiro Kohada <kohada.t2@xxxxxxxxx>]

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.

Reviewed-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Tetsuhiro Kohada <kohada.t2@xxxxxxxxx>
---
Changes in v2:
 - Split into 'write multiple sectors at once'
   and 'add error check when updating dir-entries'
Changes in v3
 - Rebase to latest exfat-dev
Changes in v4
 - Use if/else instead of conditional operator

 fs/exfat/dir.c      | 15 +++++++++------
 fs/exfat/exfat_fs.h |  1 +
 fs/exfat/misc.c     | 19 +++++++++++++++++++
 3 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index 02acbb6ddf02..7c2e29632634 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -606,13 +606,16 @@ 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->bh[i], sync);
-		brelse(es->bh[i]);
-	}
+	if (es->modified)
+		err = exfat_update_bhs(es->bh, es->num_bh, sync);
+
+	for (i = 0; i < es->num_bh; i++)
+		if (err)
+			bforget(es->bh[i]);
+		else
+			brelse(es->bh[i]);
 	kfree(es);
 }
 
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 84664024e51e..cbb00ee97183 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -512,6 +512,7 @@ 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 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 8a3dde59052b..564718747fb2 100644
--- a/fs/exfat/misc.c
+++ b/fs/exfat/misc.c
@@ -172,6 +172,25 @@ void exfat_update_bh(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