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Commit 2c49be99 authored by Paolo 'Blaisorblade' Giarrusso's avatar Paolo 'Blaisorblade' Giarrusso Committed by Linus Torvalds
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[PATCH] uml ubd: handle readonly status 



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: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
CC: Jens Axboe <axboe@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent acef2e55

arch/um/drivers/ubd_kern.c

+10 −4
Original line number Diff line number Diff line
@@ -156,6 +156,7 @@ static struct gendisk *fake_gendisk[MAX_DEV]; 
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, struct file *filp) 
		}

	}

	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 request *req, struct io_thread_req *io_req) 


	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, unsigned long address, int is_write, 


		/* 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 "