linux-kernel - [PATCH] ubi: block: Warn if volume size is not multiple of 512

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Date:   Sun,  1 Sep 2019 22:32:05 +0200
From:   Richard Weinberger <richard@....at>
To:     linux-mtd@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, Richard Weinberger <richard@....at>
Subject: [PATCH] ubi: block: Warn if volume size is not multiple of 512

If volume size is not a multiple of 512, ubi block cuts
off the last bytes of an volume since the block layer works
on 512 byte sectors.
This can happen especially on NOR flash with minimal io
size of 1.

To avoid unpleasant surprises, print a warning.

Signed-off-by: Richard Weinberger <richard@....at>
---
 drivers/mtd/ubi/block.c | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 6025398955a2..e1a2ae21dfd3 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -345,15 +345,36 @@ static const struct blk_mq_ops ubiblock_mq_ops = {
 	.init_request	= ubiblock_init_request,
 };
 
+static int calc_disk_capacity(struct ubi_volume_info *vi, u64 *disk_capacity)
+{
+	u64 size = vi->used_bytes >> 9;
+
+	if (vi->used_bytes % 512) {
+		pr_warn("UBI: block: volume size is not a multiple of 512, "
+			"last %llu bytes are ignored!\n",
+			vi->used_bytes - (size << 9));
+	}
+
+	if ((sector_t)size != size)
+		return -EFBIG;
+
+	*disk_capacity = size;
+
+	return 0;
+}
+
 int ubiblock_create(struct ubi_volume_info *vi)
 {
 	struct ubiblock *dev;
 	struct gendisk *gd;
-	u64 disk_capacity = vi->used_bytes >> 9;
+	u64 disk_capacity;
 	int ret;
 
-	if ((sector_t)disk_capacity != disk_capacity)
-		return -EFBIG;
+	ret = calc_disk_capacity(vi, &disk_capacity);
+	if (ret) {
+		return ret;
+	}
+
 	/* Check that the volume isn't already handled */
 	mutex_lock(&devices_mutex);
 	if (find_dev_nolock(vi->ubi_num, vi->vol_id)) {
@@ -507,7 +528,8 @@ int ubiblock_remove(struct ubi_volume_info *vi)
 static int ubiblock_resize(struct ubi_volume_info *vi)
 {
 	struct ubiblock *dev;
-	u64 disk_capacity = vi->used_bytes >> 9;
+	u64 disk_capacity;
+	int ret;
 
 	/*
 	 * Need to lock the device list until we stop using the device,
@@ -520,11 +542,16 @@ static int ubiblock_resize(struct ubi_volume_info *vi)
 		mutex_unlock(&devices_mutex);
 		return -ENODEV;
 	}
-	if ((sector_t)disk_capacity != disk_capacity) {
+
+	ret = calc_disk_capacity(vi, &disk_capacity);
+	if (ret) {
 		mutex_unlock(&devices_mutex);
-		dev_warn(disk_to_dev(dev->gd), "the volume is too big (%d LEBs), cannot resize",
-			 vi->size);
-		return -EFBIG;
+		if (ret == -EFBIG) {
+			dev_warn(disk_to_dev(dev->gd),
+				 "the volume is too big (%d LEBs), cannot resize",
+				 vi->size);
+		}
+		return ret;
 	}
 
 	mutex_lock(&dev->dev_mutex);
-- 
2.16.4