exfat: fix error handling for FAT table operations

Fix three error handling issues in FAT table operations:

1. Fix exfat_update_bh() to properly return errors from sync_dirty_buffer
2. Fix exfat_end_bh() to properly return errors from exfat_update_bh()
   and exfat_mirror_bh()
3. Fix ignored return values from exfat_chain_cont_cluster() in inode.c
   and namei.c

These fixes ensure that FAT table write errors are properly propagated
to the caller instead of being silently ignored.

Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

Author: Chi Zhiling

fs/exfat/exfat_fs.h

@@ -584,7 +584,7 @@ void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
 		u8 *tz, __le16 *time, __le16 *date, u8 *time_cs);
 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_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);

fs/exfat/fatent.c

@@ -25,7 +25,7 @@ static int exfat_mirror_bh(struct super_block *sb, struct buffer_head *bh)
 		if (!c_bh)
 			return -ENOMEM;
 		memcpy(c_bh->b_data, bh->b_data, sb->s_blocksize);
-		exfat_update_bh(c_bh, sb->s_flags & SB_SYNCHRONOUS);
+		err = exfat_update_bh(c_bh, sb->s_flags & SB_SYNCHRONOUS);
 		brelse(c_bh);
 	}
 
@@ -36,10 +36,10 @@ static int exfat_end_bh(struct super_block *sb, struct buffer_head *bh)
 {
 	int err;
 
-	exfat_update_bh(bh, sb->s_flags & SB_SYNCHRONOUS);
-	err = exfat_mirror_bh(sb, bh);
+	err = exfat_update_bh(bh, sb->s_flags & SB_SYNCHRONOUS);
+	if (!err)
+		err = exfat_mirror_bh(sb, bh);
 	brelse(bh);
-
 	return err;
 }
 

fs/exfat/inode.c

@@ -204,8 +204,9 @@ static int exfat_map_cluster(struct inode *inode, unsigned int clu_offset,
 				 * so fat-chain should be synced with
 				 * alloc-bitmap
 				 */
-				exfat_chain_cont_cluster(sb, ei->start_clu,
-					num_clusters);
+				if (exfat_chain_cont_cluster(sb, ei->start_clu,
+						num_clusters))
+					return -EIO;
 				ei->flags = ALLOC_FAT_CHAIN;
 			}
 			if (new_clu.flags == ALLOC_FAT_CHAIN)

fs/exfat/misc.c

@@ -161,13 +161,17 @@ u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type)
 	return chksum;
 }
 
-void exfat_update_bh(struct buffer_head *bh, int sync)
+int exfat_update_bh(struct buffer_head *bh, int sync)
 {
+	int err = 0;
+
 	set_buffer_uptodate(bh);
 	mark_buffer_dirty(bh);
 
 	if (sync)
-		sync_dirty_buffer(bh);
+		err = sync_dirty_buffer(bh);
+
+	return err;
 }
 
 int exfat_update_bhs(struct buffer_head **bhs, int nr_bhs, int sync)

fs/exfat/namei.c

@@ -365,7 +365,8 @@ int exfat_find_empty_entry(struct inode *inode,
 			/* no-fat-chain bit is disabled,
 			 * so fat-chain should be synced with alloc-bitmap
 			 */
-			exfat_chain_cont_cluster(sb, p_dir->dir, p_dir->size);
+			if (exfat_chain_cont_cluster(sb, p_dir->dir, p_dir->size))
+				return -EIO;
 			p_dir->flags = ALLOC_FAT_CHAIN;
 			hint_femp.cur.flags = ALLOC_FAT_CHAIN;
 		}