[PATCH master 2/2] block: refuse registering block devices with absurdly large blocks

[Ahmad Fatoum]

Block layer caching can't work if a block is bigger than BUFSIZE which
is used for the caching chunks. Instead of ending up with a rdbufsize
of 0, which leads to strange errors on device access, just refuse this
outright.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 common/block.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/common/block.c b/common/block.c
index 7f28b56419e2..c39269d3a692 100644
--- a/common/block.c
+++ b/common/block.c
@@ -388,6 +388,11 @@ int blockdevice_register(struct block_device *blk)
 	dev_dbg(blk->dev, "rdbufsize: %d blockbits: %d blkmask: 0x%08x\n",
 		blk->rdbufsize, blk->blockbits, blk->blkmask);
 
+	if (!blk->rdbufsize) {
+		pr_warn("block size of %u not supported\n", BLOCKSIZE(blk));
+		return -ENOSYS;
+	}
+
 	for (i = 0; i < 8; i++) {
 		struct chunk *chunk = xzalloc(sizeof(*chunk));
 		chunk->data = dma_alloc(BUFSIZE);
-- 
2.39.2