linux.git/drivers/block/loop.c, branch v6.5-rc2

block: replace fmode_t with a block-specific type for block open flags

2023-06-12T14:04:05+00:00

The only overlap between the block open flags mapped into the fmode_t and
other uses of fmode_t are FMODE_READ and FMODE_WRITE.  Define a new
blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and
->ioctl and stop abusing fmode_t.

Signed-off-by: Christoph Hellwig 
Acked-by: Jack Wang 		[rnbd]
Reviewed-by: Hannes Reinecke 
Reviewed-by: Christian Brauner 
Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de
Signed-off-by: Jens Axboe

block: remove the unused mode argument to ->release

2023-06-12T14:04:04+00:00

The mode argument to the ->release block_device_operation is never used,
so remove it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Acked-by: Christian Brauner 
Acked-by: Jack Wang 			[rnbd]
Link: https://lore.kernel.org/r/20230608110258.189493-10-hch@lst.de
Signed-off-by: Jens Axboe

block: introduce holder ops

2023-06-05T16:53:04+00:00

Add a new blk_holder_ops structure, which is passed to blkdev_get_by_* and
installed in the block_device for exclusive claims.  It will be used to
allow the block layer to call back into the user of the block device for
thing like notification of a removed device or a device resize.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Acked-by: Dave Chinner 
Reviewed-by: Dave Chinner 
Link: https://lore.kernel.org/r/20230601094459.1350643-10-hch@lst.de
Signed-off-by: Jens Axboe

loop: LOOP_CONFIGURE: send uevents for partitions

2023-03-27T19:27:06+00:00

LOOP_CONFIGURE is, as far as I understand it, supposed to be a way to
combine LOOP_SET_FD and LOOP_SET_STATUS64 into a single syscall.  When
using LOOP_SET_FD+LOOP_SET_STATUS64, a single uevent would be sent for
each partition found on the loop device after the second ioctl(), but
when using LOOP_CONFIGURE, no such uevent was being sent.

In the old setup, uevents are disabled for LOOP_SET_FD, but not for
LOOP_SET_STATUS64.  This makes sense, as it prevents uevents being
sent for a partially configured device during LOOP_SET_FD - they're
only sent at the end of LOOP_SET_STATUS64.  But for LOOP_CONFIGURE,
uevents were disabled for the entire operation, so that final
notification was never issued.  To fix this, reduce the critical
section to exclude the loop_reread_partitions() call, which causes
the uevents to be issued, to after uevents are re-enabled, matching
the behaviour of the LOOP_SET_FD+LOOP_SET_STATUS64 combination.

I noticed this because Busybox's losetup program recently changed from
using LOOP_SET_FD+LOOP_SET_STATUS64 to LOOP_CONFIGURE, and this broke
my setup, for which I want a notification from the kernel any time a
new partition becomes available.

Signed-off-by: Alyssa Ross 
[hch: reduced the critical section]
Signed-off-by: Christoph Hellwig 
Fixes: 3448914e8cc5 ("loop: Add LOOP_CONFIGURE ioctl")
Link: https://lore.kernel.org/r/20230320125430.55367-1-hch@lst.de
Signed-off-by: Jens Axboe

loop: Fix use-after-free issues

2023-03-15T01:20:48+00:00

do_req_filebacked() calls blk_mq_complete_request() synchronously or
asynchronously when using asynchronous I/O unless memory allocation fails.
Hence, modify loop_handle_cmd() such that it does not dereference 'cmd' nor
'rq' after do_req_filebacked() finished unless we are sure that the request
has not yet been completed. This patch fixes the following kernel crash:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000054
Call trace:
 css_put.42938+0x1c/0x1ac
 loop_process_work+0xc8c/0xfd4
 loop_rootcg_workfn+0x24/0x34
 process_one_work+0x244/0x558
 worker_thread+0x400/0x8fc
 kthread+0x16c/0x1e0
 ret_from_fork+0x10/0x20

Cc: Christoph Hellwig 
Cc: Ming Lei 
Cc: Jan Kara 
Cc: Johannes Weiner 
Cc: Dan Schatzberg 
Fixes: c74d40e8b5e2 ("loop: charge i/o to mem and blk cg")
Fixes: bc07c10a3603 ("block: loop: support DIO & AIO")
Signed-off-by: Bart Van Assche 
Reviewed-by: Ming Lei 
Link: https://lore.kernel.org/r/20230314182155.80625-1-bvanassche@acm.org
Signed-off-by: Jens Axboe

loop: loop_set_status_from_info() check before assignment

2023-02-23T03:43:09+00:00

In loop_set_status_from_info(), lo->lo_offset and lo->lo_sizelimit should
be checked before reassignment, because if an overflow error occurs, the
original correct value will be changed to the wrong value, and it will not
be changed back.

More, the original patch did not solve the problem, the value was set and
ioctl returned an error, but the subsequent io used the value in the loop
driver, which still caused an alarm:

loop_handle_cmd
 do_req_filebacked
  loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
  lo_rw_aio
   cmd->iocb.ki_pos = pos

Fixes: c490a0b5a4f3 ("loop: Check for overflow while configuring loop")
Signed-off-by: Zhong Jinghua 
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20230221095027.3656193-1-zhongjinghua@huaweicloud.com
Signed-off-by: Jens Axboe

loop: Improve the hw_queue_depth kernel module parameter implementation

2023-02-01T15:16:11+00:00

Make the following minor changes which were reported by colleagues
while reviewing this code:
- Remove the parentheses from around the LOOP_DEFAULT_HW_Q_DEPTH
  definition since these are superfluous.
- Accept other number formats than decimal, e.g. hexadecimal.
- Do not set hw_queue_depth to an out-of-range value, even if that value
  won't be used.
- Use the LOOP_DEFAULT_HW_Q_DEPTH macro in the kernel module parameter
  description to prevent that the description gets out of sync.

This patch has been tested as follows:

 # modprobe -r loop
 # modprobe loop hw_queue_depth=-1
 modprobe: ERROR: could not insert 'loop': Invalid argument
 # modprobe loop hw_queue_depth=0
 modprobe: ERROR: could not insert 'loop': Invalid argument
 # modprobe loop hw_queue_depth=1; cat /sys/module/loop/parameters/hw_queue_depth
 1
 # modprobe -r loop; modprobe loop; cat /sys/module/loop/parameters/hw_queue_depth hw_queue_depth=0x10
 16
 # modprobe -r loop; modprobe loop; cat /sys/module/loop/parameters/hw_queue_depth hw_queue_depth=128
 128
 # modprobe -r loop; modprobe loop hw_queue_depth=129; cat /sys/module/loop/parameters/hw_queue_depth
 129
 # modprobe -r loop; modprobe loop hw_queue_depth=$((1<<32))
 modprobe: ERROR: could not insert 'loop': Numerical result out of range

See also commit ef44c50837ab ("loop: allow user to set the queue
depth").

Cc: Chaitanya Kulkarni 
Cc: Himanshu Madhani 
Signed-off-by: Bart Van Assche 
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20230130211347.832110-1-bvanassche@acm.org
Signed-off-by: Jens Axboe

treewide: Convert del_timer() to timer_shutdown()

2022-12-25T21:38:09+00:00

Due to several bugs caused by timers being re-armed after they are
shutdown and just before they are freed, a new state of timers was added
called "shutdown".  After a timer is set to this state, then it can no
longer be re-armed.

The following script was run to find all the trivial locations where
del_timer() or del_timer_sync() is called in the same function that the
object holding the timer is freed.  It also ignores any locations where
the timer->function is modified between the del_timer*() and the free(),
as that is not considered a "trivial" case.

This was created by using a coccinelle script and the following
commands:

    $ cat timer.cocci
    @@
    expression ptr, slab;
    identifier timer, rfield;
    @@
    (
    -       del_timer(&ptr->timer);
    +       timer_shutdown(&ptr->timer);
    |
    -       del_timer_sync(&ptr->timer);
    +       timer_shutdown_sync(&ptr->timer);
    )
      ... when strict
          when != ptr->timer
    (
            kfree_rcu(ptr, rfield);
    |
            kmem_cache_free(slab, ptr);
    |
            kfree(ptr);
    )

    $ spatch timer.cocci . > /tmp/t.patch
    $ patch -p1 < /tmp/t.patch

Link: https://lore.kernel.org/lkml/20221123201306.823305113@linutronix.de/
Signed-off-by: Steven Rostedt (Google) 
Acked-by: Pavel Machek  [ LED ]
Acked-by: Kalle Valo  [ wireless ]
Acked-by: Paolo Abeni  [ networking ]
Signed-off-by: Linus Torvalds

loop: Fix the max_loop commandline argument treatment when it is set to 0

2022-12-14T17:55:20+00:00

Currently, the max_loop commandline argument can be used to specify how
many loop block devices are created at init time. If it is not
specified on the commandline, CONFIG_BLK_DEV_LOOP_MIN_COUNT loop block
devices will be created.

The max_loop commandline argument can be used to override the value of
CONFIG_BLK_DEV_LOOP_MIN_COUNT. However, when max_loop is set to 0
through the commandline, the current logic treats it as if it had not
been set, and creates CONFIG_BLK_DEV_LOOP_MIN_COUNT devices anyway.

Fix this by starting max_loop off as set to CONFIG_BLK_DEV_LOOP_MIN_COUNT.
This preserves the intended behavior of creating
CONFIG_BLK_DEV_LOOP_MIN_COUNT loop block devices if the max_loop
commandline parameter is not specified, and allowing max_loop to
be respected for all values, including 0.

This allows environments that can create all of their required loop
block devices on demand to not have to unnecessarily preallocate loop
block devices.

Fixes: 732850827450 ("remove artificial software max_loop limit")
Cc: stable@vger.kernel.org
Cc: Ken Chen 
Signed-off-by: Isaac J. Manjarres 
Link: https://lore.kernel.org/r/20221208212902.765781-1-isaacmanjarres@google.com
Signed-off-by: Jens Axboe

use less confusing names for iov_iter direction initializers

2022-11-25T18:01:55+00:00

READ/WRITE proved to be actively confusing - the meanings are
"data destination, as used with read(2)" and "data source, as
used with write(2)", but people keep interpreting those as
"we read data from it" and "we write data to it", i.e. exactly
the wrong way.

Call them ITER_DEST and ITER_SOURCE - at least that is harder
to misinterpret...

Signed-off-by: Al Viro