From: Paolo 'Blaisorblade' Giarrusso Use the set_disk_ro() API when the backing file is read-only, to mark the disk read-only, during the ->open(). The current hack does not work when doing a mount -o remount. Also, mark explicitly the code paths which should no more be triggerable (I've removed the WARN_ON(1) things). They should actually become BUG()s probably but I'll avoid that since I'm not so sure the change works so well. I gave it only some limited testing. Signed-off-by: Paolo 'Blaisorblade' Giarrusso CC: Jens Axboe Signed-off-by: Andrew Morton --- arch/um/drivers/ubd_kern.c | 14 ++++++++++---- 1 files changed, 10 insertions(+), 4 deletions(-) diff -puN arch/um/drivers/ubd_kern.c~uml-ubd-handle-readonly-status arch/um/drivers/ubd_kern.c --- 25/arch/um/drivers/ubd_kern.c~uml-ubd-handle-readonly-status 2005-04-26 04:25:31.762388704 -0700 +++ 25-akpm/arch/um/drivers/ubd_kern.c 2005-04-26 04:25:31.767387944 -0700 @@ -156,6 +156,7 @@ static struct gendisk *fake_gendisk[MAX_ static struct openflags global_openflags = OPEN_FLAGS; struct cow { + /* This is the backing file, actually */ char *file; int fd; unsigned long *bitmap; @@ -927,10 +928,14 @@ static int ubd_open(struct inode *inode, } } dev->count++; - if((filp->f_mode & FMODE_WRITE) && !dev->openflags.w){ + set_disk_ro(disk, !dev->openflags.w); + + /* This should no more be needed. And it didn't work anyway to exclude + * read-write remounting of filesystems.*/ + /*if((filp->f_mode & FMODE_WRITE) && !dev->openflags.w){ if(--dev->count == 0) ubd_close(dev); err = -EROFS; - } + }*/ out: return(err); } @@ -1096,6 +1101,7 @@ static int prepare_request(struct reques if(req->rq_status == RQ_INACTIVE) return(1); + /* This should be impossible now */ if((rq_data_dir(req) == WRITE) && !dev->openflags.w){ printk("Write attempted on readonly ubd device %s\n", disk->disk_name); @@ -1243,6 +1249,7 @@ static int ubd_check_remapped(int fd, un /* It's a write to a ubd device */ + /* This should be impossible now */ if(!dev->openflags.w){ /* It's a write access on a read-only device - probably * shouldn't happen. If the kernel is trying to change @@ -1605,8 +1612,7 @@ void do_io(struct io_thread_req *req) } } while((n < len) && (n != 0)); if (n < len) memset(&buf[n], 0, len - n); - } - else { + } else { n = os_write_file(req->fds[bit], buf, len); if(n != len){ printk("do_io - write failed err = %d " _