[PATCH] f2fs: fix oops of set_bit_le in arm64 architecture

[Chao Yu]

As Adam borowski reported:

"The filesystem mounts fine on amd64 on 4.11-rc1, it also works fine with
both next-20170216 and 4.9 on arm64.

The machine in question is not fully mainlined yet, I'm using Icenowy's
patchsets from git@xxxxxxxxxx:Icenowy/linux.git; I have no other arm64
hardware to test (could try qemu...).

good: icenowy/sunxi64-next-20170216
bad:  icenowy/sunxi64-4.11-rc1

[<ffff000008463798>] set_bit+0x18/0x30
[<ffff0000083f4640>] scan_nat_page+0xe0/0x118
[<ffff0000083f4784>] build_free_nids+0x10c/0x5e8
[<ffff0000083f6fe4>] build_node_manager+0x394/0x3d0
[<ffff0000083e2d1c>] f2fs_fill_super+0x884/0x11e0
[<ffff0000081f26d8>] mount_bdev+0x190/0x1b8
[<ffff0000083e0c84>] f2fs_mount+0x14/0x20
[<ffff0000081f355c>] mount_fs+0x4c/0x168
[<ffff000008210bc0>] vfs_kern_mount+0x50/0x130
[<ffff000008213700>] do_mount+0x1b0/0xbb8
[<ffff000008214494>] SyS_mount+0x8c/0xf8
[<ffff000008b110ac>] mount_block_root+0x100/0x25c
[<ffff000008b11324>] mount_root+0x11c/0x134
[<ffff000008b11478>] prepare_namespace+0x13c/0x184
[<ffff000008b10d70>] kernel_init_freeable+0x214/0x238
[<ffff0000088445d8>] kernel_init+0x10/0x100
[<ffff000008082ec0>] ret_from_fork+0x10/0x50
Code: d2800022 8b400c21 f9800031 9ac32043 (c85f7c22)
---[ end trace a8a385a1e8cd5a36 ]---
Kernel panic - not syncing: Attempted to kill init! "

The reason is in arm64 architecture there is restriction for parameter
@addr of {set,clear}_bit_le, the value of it must be 64-bits aligned.

In this patch we will change each bitmap size of NAT block to be 64-bits
aligned to avoid that issue.

Reported-by: Adam Borowski <kilobyte@xxxxxxxxxx>
Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
 include/linux/f2fs_fs.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index e2d239ed4c60..92697f3fff7b 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -279,7 +279,7 @@ struct f2fs_node {
  * For NAT entries
  */
 #define NAT_ENTRY_PER_BLOCK (PAGE_SIZE / sizeof(struct f2fs_nat_entry))
-#define NAT_ENTRY_BITMAP_SIZE	((NAT_ENTRY_PER_BLOCK + 7) / 8)
+#define NAT_ENTRY_BITMAP_SIZE	((NAT_ENTRY_PER_BLOCK + 63) / 8)
 
 struct f2fs_nat_entry {
 	__u8 version;		/* latest version of cached nat entry */
-- 
2.8.2.295.g3f1c1d0