Re: [PATCH 4/5] brd: limit maximal block size to 32M
From: Keith Busch <kbusch@kernel.org>
Date: 2023-03-06 18:02:32
On Mon, Mar 06, 2023 at 01:01:26PM +0100, Hannes Reinecke wrote:
quoted hunk ↗ jump to hunk
Use an arbitrary limit of 32M for the maximal blocksize so as not to overflow the page cache. Signed-off-by: Hannes Reinecke <hare@suse.de> --- drivers/block/brd.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 11bac3c3f1b6..1ed114cd5cb0 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c@@ -348,6 +348,7 @@ static int max_part = 1; module_param(max_part, int, 0444); MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices"); +#define RD_MAX_SECTOR_SIZE 65536 static unsigned int rd_blksize = PAGE_SIZE; module_param(rd_blksize, uint, 0444); MODULE_PARM_DESC(rd_blksize, "Blocksize of each RAM disk in bytes.");@@ -410,15 +411,14 @@ static int brd_alloc(int i) disk->private_data = brd; strscpy(disk->disk_name, buf, DISK_NAME_LEN); set_capacity(disk, rd_size * 2); - - /* - * This is so fdisk will align partitions on 4k, because of - * direct_access API needing 4k alignment, returning a PFN - * (This is only a problem on very small devices <= 4M, - * otherwise fdisk will align on 1M. Regardless this call - * is harmless) - */ + + if (rd_blksize > RD_MAX_SECTOR_SIZE) {
rd_blkside is in bytes, but the above is ccomapring it to something in units of SECTOR_SIZE.
+ /* Arbitrary limit maximum block size to 32M */ + err = -EINVAL; + goto out_cleanup_disk; + }
rd_blksize also needs to be >= 512, and a power of 2.
blk_queue_physical_block_size(disk->queue, rd_blksize); + blk_queue_max_hw_sectors(disk->queue, RD_MAX_SECTOR_SIZE); /* Tell the block layer that this is not a rotational device */ blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);