| From stable-bounces@linux.kernel.org Sun Jul 15 23:49:08 2007 |
| From: Jeff Dike <jdike@addtoit.com> |
| Date: Sun, 15 Jul 2007 23:38:58 -0700 |
| Subject: uml: limit request size on COWed devices |
| To: torvalds@linux-foundation.org |
| Cc: akpm@linux-foundation.org, jdike@linux.intel.com, blaisorblade@yahoo.it, jdike@addtoit.com, stable@kernel.org |
| Message-ID: <200707160638.l6G6cw5e014373@imap1.linux-foundation.org> |
| |
| |
| From: Jeff Dike <jdike@addtoit.com> |
| |
| COWed devices can't handle more than 32 (64 on x86_64) sectors in one request |
| due to the size of the bitmap being carried around in the io_thread_req. |
| |
| Enforce that by telling the block layer not to put too many sectors in |
| requests to COWed devices. |
| |
| Signed-off-by: Jeff Dike <jdike@linux.intel.com> |
| Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| arch/um/drivers/ubd_kern.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/arch/um/drivers/ubd_kern.c |
| +++ b/arch/um/drivers/ubd_kern.c |
| @@ -712,6 +712,8 @@ static int ubd_add(int n, char **error_o |
| ubd_dev->queue->queuedata = ubd_dev; |
| |
| blk_queue_max_hw_segments(ubd_dev->queue, MAX_SG); |
| + if(ubd_dev->cow.file != NULL) |
| + blk_queue_max_sectors(ubd_dev->queue, 8 * sizeof(long)); |
| err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]); |
| if(err){ |
| *error_out = "Failed to register device"; |
