Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH] [12/99] loop: handle on-demand devices correctly | Date | Wed, 27 Jul 2011 14:48:10 -0700 (PDT) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Namhyung Kim <namhyung@gmail.com>
commit a1c15c59feee36267c43142a41152fbf7402afb6 upstream.
When finding or allocating a loop device, loop_probe() did not take partition numbers into account so that it can result to a different device. Consider following example:
$ sudo modprobe loop max_part=15 $ ls -l /dev/loop* brw-rw---- 1 root disk 7, 0 2011-05-24 22:16 /dev/loop0 brw-rw---- 1 root disk 7, 16 2011-05-24 22:16 /dev/loop1 brw-rw---- 1 root disk 7, 32 2011-05-24 22:16 /dev/loop2 brw-rw---- 1 root disk 7, 48 2011-05-24 22:16 /dev/loop3 brw-rw---- 1 root disk 7, 64 2011-05-24 22:16 /dev/loop4 brw-rw---- 1 root disk 7, 80 2011-05-24 22:16 /dev/loop5 brw-rw---- 1 root disk 7, 96 2011-05-24 22:16 /dev/loop6 brw-rw---- 1 root disk 7, 112 2011-05-24 22:16 /dev/loop7 $ sudo mknod /dev/loop8 b 7 128 $ sudo losetup /dev/loop8 ~/temp/disk-with-3-parts.img $ sudo losetup -a /dev/loop128: [0805]:278201 (/home/namhyung/temp/disk-with-3-parts.img) $ ls -l /dev/loop* brw-rw---- 1 root disk 7, 0 2011-05-24 22:16 /dev/loop0 brw-rw---- 1 root disk 7, 16 2011-05-24 22:16 /dev/loop1 brw-rw---- 1 root disk 7, 2048 2011-05-24 22:18 /dev/loop128 brw-rw---- 1 root disk 7, 2049 2011-05-24 22:18 /dev/loop128p1 brw-rw---- 1 root disk 7, 2050 2011-05-24 22:18 /dev/loop128p2 brw-rw---- 1 root disk 7, 2051 2011-05-24 22:18 /dev/loop128p3 brw-rw---- 1 root disk 7, 32 2011-05-24 22:16 /dev/loop2 brw-rw---- 1 root disk 7, 48 2011-05-24 22:16 /dev/loop3 brw-rw---- 1 root disk 7, 64 2011-05-24 22:16 /dev/loop4 brw-rw---- 1 root disk 7, 80 2011-05-24 22:16 /dev/loop5 brw-rw---- 1 root disk 7, 96 2011-05-24 22:16 /dev/loop6 brw-rw---- 1 root disk 7, 112 2011-05-24 22:16 /dev/loop7 brw-r--r-- 1 root root 7, 128 2011-05-24 22:17 /dev/loop8
After this patch, /dev/loop8 - instead of /dev/loop128 - was accessed correctly.
In addition, 'range' passed to blk_register_region() should include all range of dev_t that LOOP_MAJOR can address. It does not need to be limited by partition numbers unless 'max_loop' param was specified.
Signed-off-by: Namhyung Kim <namhyung@gmail.com> Cc: Laurent Vivier <Laurent.Vivier@bull.net> Signed-off-by: Jens Axboe <jaxboe@fusionio.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- drivers/block/loop.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
Index: linux-2.6.35.y/drivers/block/loop.c =================================================================== --- linux-2.6.35.y.orig/drivers/block/loop.c +++ linux-2.6.35.y/drivers/block/loop.c @@ -1579,7 +1579,7 @@ static struct kobject *loop_probe(dev_t struct kobject *kobj; mutex_lock(&loop_devices_mutex); - lo = loop_init_one(dev & MINORMASK); + lo = loop_init_one(MINOR(dev) >> part_shift); kobj = lo ? get_disk(lo->lo_disk) : ERR_PTR(-ENOMEM); mutex_unlock(&loop_devices_mutex); @@ -1620,10 +1620,10 @@ static int __init loop_init(void) if (max_loop) { nr = max_loop; - range = max_loop; + range = max_loop << part_shift; } else { nr = 8; - range = 1UL << (MINORBITS - part_shift); + range = 1UL << MINORBITS; } if (register_blkdev(LOOP_MAJOR, "loop")) @@ -1662,7 +1662,7 @@ static void __exit loop_exit(void) unsigned long range; struct loop_device *lo, *next; - range = max_loop ? max_loop : 1UL << (MINORBITS - part_shift); + range = max_loop ? max_loop << part_shift : 1UL << MINORBITS; list_for_each_entry_safe(lo, next, &loop_devices, lo_list) loop_del_one(lo);
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