[PATCH] f2fs: fix 32-bit build

[Arnd Bergmann <arnd@arndb.de>]

The addition of multiple-device support broke CONFIG_BLK_DEV_ZONED
on 32-bit machines because of a 64-bit division:

fs/f2fs/f2fs.o: In function `__issue_discard_async':
extent_cache.c:(.text.__issue_discard_async+0xd4): undefined reference to `__aeabi_uldivmod'

Unfortunately, the sector number is usually a 64-bit number, and
we probably can't guarantee that bdev_zone_size() returns a
power-of-two number, so we actually have to do the expensive 64-bit
operation to get the remainder.

Fixes: 792b84b74b54 ("f2fs: support multiple devices")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 fs/f2fs/segment.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 634834e5a232..e4c5497aa172 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -685,6 +685,7 @@ static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
 {
 	sector_t nr_sects = SECTOR_FROM_BLOCK(blklen);
 	sector_t sector;
+	u32 rem;
 	int devi = 0;
 
 	if (sbi->s_ndevs) {
@@ -693,7 +694,8 @@ static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
 	}
 	sector = SECTOR_FROM_BLOCK(blkstart);
 
-	if (sector % bdev_zone_size(bdev) || nr_sects != bdev_zone_size(bdev)) {
+	div_u64_rem(sector, bdev_zone_size(bdev), &rem);
+	if (rem || nr_sects != bdev_zone_size(bdev)) {
 		f2fs_msg(sbi->sb, KERN_INFO,
 			"(%d) %s: Unaligned discard attempted (block %x + %x)",
 			devi, sbi->s_ndevs ? FDEV(devi).path: "",
-- 
2.9.0