[PATCH v2] mm, swap: disallow swapon() on zoned block devices

[Naohiro Aota <naohiro.aota@wdc.com>]

A zoned block device consists of a number of zones. Zones are either
conventional and accepting random writes or sequential and requiring that
writes be issued in LBA order from each zone write pointer position. For
the write restriction, zoned block devices are not suitable for a swap
device. Disallow swapon on them.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
v2: add comments according to Christoph's feedback, reformat chengelog.
---
 mm/swapfile.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index dab43523afdd..f2c4224d1f8a 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2887,6 +2887,14 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
 		error = set_blocksize(p->bdev, PAGE_SIZE);
 		if (error < 0)
 			return error;
+		/*
+		 * Zoned block device contains zones that have
+		 * sequential write only restriction. For the restriction,
+		 * zoned block devices are not suitable for a swap device.
+		 * Disallow them here.
+		 */
+		if (blk_queue_is_zoned(p->bdev->bd_queue))
+			return -EINVAL;
 		p->flags |= SWP_BLKDEV;
 	} else if (S_ISREG(inode->i_mode)) {
 		p->bdev = inode->i_sb->s_bdev;
-- 
2.23.0