[PATCH] erofs: handle 48-bit blocks/uniaddr for extra devices

[Zhan Xusheng]

erofs_init_device() only reads blocks_lo and uniaddr_lo from the
on-disk device slot, ignoring blocks_hi and uniaddr_hi that were
introduced alongside the 48-bit block addressing feature.

For the primary device (dif0), erofs_read_superblock() already handles
this correctly by combining blocks_lo with blocks_hi when 48-bit
layout is enabled.  But the same logic was not applied to extra
devices.

With a 48-bit EROFS image using extra devices whose uniaddr or blocks
exceed 32-bit range, the truncated values cause erofs_map_dev() to
compute wrong physical addresses, leading to silent data corruption.

Fix this by reading blocks_hi and uniaddr_hi in erofs_init_device()
when 48-bit layout is enabled, consistent with the primary device
handling.

Fixes: 61ba89b57905 ("erofs: add 48-bit block addressing on-disk support")
Signed-off-by: Zhan Xusheng <zhanxusheng at xiaomi.com>
---
Note: erofs-utils also needs corresponding fixes for the write path
(erofs_mkfs_format_devices) and a swapped hi/lo read in
erofs_read_superblock, which will be sent separately.
---
 fs/erofs/super.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 972a0c82198d..a04e70ef4fcc 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -177,6 +177,10 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb,
 
 	dif->blocks = le32_to_cpu(dis->blocks_lo);
 	dif->uniaddr = le32_to_cpu(dis->uniaddr_lo);
+	if (erofs_sb_has_48bit(sbi)) {
+		dif->blocks |= (u64)le32_to_cpu(dis->blocks_hi) << 32;
+		dif->uniaddr |= (u64)le16_to_cpu(dis->uniaddr_hi) << 32;
+	}
 	sbi->total_blocks += dif->blocks;
 	*pos += EROFS_DEVT_SLOT_SIZE;
 	return 0;
-- 
2.43.0