From b0516833d8096c40ead3169c90d87392fb5f8f45 Mon Sep 17 00:00:00 2001

From: Tetsuhiro Kohada <Kohada.Tetsuhiro@dc.MitsubishiElectric.co.jp>

Date: Tue, 21 Apr 2020 10:58:58 +0900

Subject: [Backport b0516833d809] exfat: Unify access to the boot sector

Unify access to boot sector via 'sbi->pbr_bh'.

This fixes vol_flags inconsistency at read failed in fs_set_vol_flags(),

and buffer_head leak in __exfat_fill_super().

Signed-off-by: Tetsuhiro Kohada <Kohada.Tetsuhiro@dc.MitsubishiElectric.co.jp>

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>

---

 src/balloc.c |  3 ---

 src/super.c  | 43 ++++++++++++++++---------------------------

 2 files changed, 16 insertions(+), 30 deletions(-)

diff --git a/src/balloc.c b/src/balloc.c

index 6a04cc02565a1f3823ad9a109238bad9553a82f1..6774a5a6ded8290fb790bf70f04a1c6e3253cd7a 100644

--- a/src/balloc.c

+++ b/src/balloc.c

@@ -91,7 +91,6 @@ static int exfat_allocate_bitmap(struct super_block *sb,

 		}

 	}

-	sbi->pbr_bh = NULL;

 	return 0;

 }

@@ -137,8 +136,6 @@ void exfat_free_bitmap(struct exfat_sb_info *sbi)

 {

 	int i;

-	brelse(sbi->pbr_bh);

-

 	for (i = 0; i < sbi->map_sectors; i++)

 		__brelse(sbi->vol_amap[i]);

diff --git a/src/super.c b/src/super.c

index 86c87560602400ec2bc7587268bf025cc54e9ce7..6b63e5092628143ba5c8f3a5437eb3f5a1b68ea7 100644

--- a/src/super.c

+++ b/src/super.c

@@ -49,6 +49,7 @@ static void exfat_put_super(struct super_block *sb)

 		sync_blockdev(sb->s_bdev);

 	exfat_set_vol_flags(sb, VOL_CLEAN);

 	exfat_free_bitmap(sbi);

+	brelse(sbi->pbr_bh);

 	mutex_unlock(&sbi->s_lock);

 	call_rcu(&sbi->rcu, exfat_delayed_free);

@@ -100,7 +101,7 @@ static int exfat_statfs(struct dentry *dentry, struct kstatfs *buf)

 int exfat_set_vol_flags(struct super_block *sb, unsigned short new_flag)

 {

 	struct exfat_sb_info *sbi = EXFAT_SB(sb);

-	struct pbr64 *bpb;

+	struct pbr64 *bpb = (struct pbr64 *)sbi->pbr_bh->b_data;

 	bool sync = 0;

 	/* flags are not changed */

@@ -115,15 +116,6 @@ int exfat_set_vol_flags(struct super_block *sb, unsigned short new_flag)

 	if (sb_rdonly(sb))

 		return 0;

-	if (!sbi->pbr_bh) {

-		sbi->pbr_bh = sb_bread(sb, 0);

-		if (!sbi->pbr_bh) {

-			exfat_msg(sb, KERN_ERR, "failed to read boot sector");

-			return -ENOMEM;

-		}

-	}

-

-	bpb = (struct pbr64 *)sbi->pbr_bh->b_data;

 	bpb->bsx.vol_flags = cpu_to_le16(new_flag);

 	if (new_flag == VOL_DIRTY && !buffer_dirty(sbi->pbr_bh))

@@ -355,10 +347,10 @@ static int exfat_read_root(struct inode *inode)

 	return 0;

 }

-static struct pbr *exfat_read_pbr_with_logical_sector(struct super_block *sb,

-		struct buffer_head **prev_bh)

+static struct pbr *exfat_read_pbr_with_logical_sector(struct super_block *sb)

 {

-	struct pbr *p_pbr = (struct pbr *) (*prev_bh)->b_data;

+	struct exfat_sb_info *sbi = EXFAT_SB(sb);

+	struct pbr *p_pbr = (struct pbr *) (sbi->pbr_bh)->b_data;

 	unsigned short logical_sect = 0;

 	logical_sect = 1 << p_pbr->bsx.f64.sect_size_bits;

@@ -378,26 +370,23 @@ static struct pbr *exfat_read_pbr_with_logical_sector(struct super_block *sb,

 	}

 	if (logical_sect > sb->s_blocksize) {

-		struct buffer_head *bh = NULL;

-

-		__brelse(*prev_bh);

-		*prev_bh = NULL;

+		brelse(sbi->pbr_bh);

+		sbi->pbr_bh = NULL;

 		if (!sb_set_blocksize(sb, logical_sect)) {

 			exfat_msg(sb, KERN_ERR,

 				"unable to set blocksize %u", logical_sect);

 			return NULL;

 		}

-		bh = sb_bread(sb, 0);

-		if (!bh) {

+		sbi->pbr_bh = sb_bread(sb, 0);

+		if (!sbi->pbr_bh) {

 			exfat_msg(sb, KERN_ERR,

 				"unable to read boot sector (logical sector size = %lu)",

 				sb->s_blocksize);

 			return NULL;

 		}

-		*prev_bh = bh;

-		p_pbr = (struct pbr *) bh->b_data;

+		p_pbr = (struct pbr *)sbi->pbr_bh->b_data;

 	}

 	return p_pbr;

 }

@@ -408,21 +397,20 @@ static int __exfat_fill_super(struct super_block *sb)

 	int ret;

 	struct pbr *p_pbr;

 	struct pbr64 *p_bpb;

-	struct buffer_head *bh;

 	struct exfat_sb_info *sbi = EXFAT_SB(sb);

 	/* set block size to read super block */

 	sb_min_blocksize(sb, 512);

 	/* read boot sector */

-	bh = sb_bread(sb, 0);

-	if (!bh) {

+	sbi->pbr_bh = sb_bread(sb, 0);

+	if (!sbi->pbr_bh) {

 		exfat_msg(sb, KERN_ERR, "unable to read boot sector");

 		return -EIO;

 	}

 	/* PRB is read */

-	p_pbr = (struct pbr *)bh->b_data;

+	p_pbr = (struct pbr *)sbi->pbr_bh->b_data;

 	/* check the validity of PBR */

 	if (le16_to_cpu((p_pbr->signature)) != PBR_SIGNATURE) {

@@ -433,7 +421,7 @@ static int __exfat_fill_super(struct super_block *sb)

 	/* check logical sector size */

-	p_pbr = exfat_read_pbr_with_logical_sector(sb, &bh;;

+	p_pbr = exfat_read_pbr_with_logical_sector(sb);

 	if (!p_pbr) {

 		ret = -EIO;

 		goto free_bh;

@@ -514,7 +502,7 @@ static int __exfat_fill_super(struct super_block *sb)

 free_upcase_table:

 	exfat_free_upcase_table(sbi);

 free_bh:

-	brelse(bh);

+	brelse(sbi->pbr_bh);

 	return ret;

 }

@@ -606,6 +594,7 @@ static int exfat_fill_super(struct super_block *sb, struct fs_context *fc)

 free_table:

 	exfat_free_upcase_table(sbi);

 	exfat_free_bitmap(sbi);

+	brelse(sbi->pbr_bh);

 check_nls_io:

 	unload_nls(sbi->nls_io);

-- 

2.31.1