linux-stable.git/block/genhd.c, branch linux-5.2.y

block: Convert blk_invalidate_devt() header into a non-kernel-doc header

2019-05-31T21:12:34+00:00

This patch avoids that the kernel-doc tool warns about this function
header when building with W=1.

Reviewed-by: Chaitanya Kulkarni 
Signed-off-by: Bart Van Assche 
Signed-off-by: Jens Axboe

block: add SPDX tags to block layer files missing licensing information

2019-04-30T22:12:03+00:00

Various block layer files do not have any licensing information at all.
Add SPDX tags for the default kernel GPLv2 license to those.

Reviewed-by: Chaitanya Kulkarni 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: fix use-after-free on gendisk

2019-04-22T15:48:12+00:00

commit 2da78092dda "block: Fix dev_t minor allocation lifetime"
specifically moved blk_free_devt(dev->devt) call to part_release()
to avoid reallocating device number before the device is fully
shutdown.

However, it can cause use-after-free on gendisk in get_gendisk().
We use md device as example to show the race scenes:

Process1		Worker			Process2
md_free
						blkdev_open
del_gendisk
  add delete_partition_work_fn() to wq
  						__blkdev_get
						get_gendisk
put_disk
  disk_release
    kfree(disk)
    						find part from ext_devt_idr
						get_disk_and_module(disk)
    					  	cause use after free

    			delete_partition_work_fn
			put_device(part)
    		  	part_release
		    	remove part from ext_devt_idr

Before  is removed from ext_devt_idr by
delete_partition_work_fn(), we can find the devt and then access
gendisk by hd_struct pointer. But, if we access the gendisk after
it have been freed, it can cause in use-after-freeon gendisk in
get_gendisk().

We fix this by adding a new helper blk_invalidate_devt() in
delete_partition() and del_gendisk(). It replaces hd_struct
pointer in idr with value 'NULL', and deletes the entry from
idr in part_release() as we do now.

Thanks to Jan Kara for providing the solution and more clear comments
for the code.

Fixes: 2da78092dda1 ("block: Fix dev_t minor allocation lifetime")
Cc: Al Viro 
Reviewed-by: Bart Van Assche 
Reviewed-by: Keith Busch 
Reviewed-by: Jan Kara 
Suggested-by: Jan Kara 
Signed-off-by: Yufen Yu 
Signed-off-by: Jens Axboe

block: check_events: don't bother with events if unsupported

2019-04-12T19:35:28+00:00

Drivers now report to the block layer if they support media change
events. If this is not the case, there's no need to allocate the event
structure, and all event handling code can effectively be skipped. This
simplifies code flow in particular for non-removable sd devices.

This effectively reverts commit 75e3f3ee3c64 ("block: always allocate
genhd->ev if check_events is implemented").

The sysfs files for the events are kept in place even if no events are
supported, as user space may rely on them being present. The only
difference is that an error code is now returned if the user tries to
set poll_msecs.

Reviewed-by: Hannes Reinecke 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Martin Wilck 
Signed-off-by: Jens Axboe

block: disk_events: introduce event flags

2019-04-12T19:35:24+00:00

Currently, an empty disk->events field tells the block layer not to
forward media change events to user space. This was done in commit
7c88a168da80 ("block: don't propagate unlisted DISK_EVENTs to userland")
in order to avoid events from "fringe" drivers to be forwarded to user
space. By doing so, the block layer lost the information which events
were supported by a particular block device, and most importantly,
whether or not a given device supports media change events at all.

Prepare for not interpreting the "events" field this way in the future
any more. This is done by adding an additional field "event_flags" to
struct gendisk, and two flag bits that can be set to have the device
treated like one that had the "events" field set to a non-zero value
before. This applies only to the sd and sr drivers, which are changed to
set the new flags.

The new flags are DISK_EVENT_FLAG_POLL to enforce polling of the device
for synchronous events, and DISK_EVENT_FLAG_UEVENT to tell the
blocklayer to generate udev events from kernel events.

In order to add the event_flags field to struct gendisk, the events
field is converted to an "unsigned short"; it doesn't need to hold
values bigger than 2 anyway.

This patch doesn't change behavior.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Martin Wilck 
Signed-off-by: Jens Axboe

block: genhd: remove async_events field

2019-04-12T19:35:22+00:00

The async_events field, intended to be used for drivers that support
asynchronous notifications about disk events (aka media change events),
isn't currently used by any driver, and apparently that has been that
way for a long time (if not forever). Remove it.

Reviewed-by: Hannes Reinecke 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Martin Wilck 
Signed-off-by: Jens Axboe

block: Replace function name in string with func

2019-02-28T21:09:08+00:00

Replace hard coded function name register_blkdev with __func__, to
improve robustness and to conform to the Linux kernel coding
style. Issue found using checkpatch.

Signed-off-by: Keyur Patel 
Signed-off-by: Jens Axboe

block: fix NULL pointer dereference in register_disk

2019-02-28T21:01:36+00:00

If __device_add_disk-->bdi_register_owner-->bdi_register-->
bdi_register_va-->device_create_vargs fails, bdi->dev is still
NULL, __device_add_disk-->register_disk will visit bdi->dev->kobj.
This patch fixes that.

Signed-off-by: zhengbin 
Signed-off-by: Jens Axboe

block: return just one value from part_in_flight

2018-12-10T15:30:38+00:00

The previous patches deleted all the code that needed the second value
returned from part_in_flight - now the kernel only uses the first value.

Consequently, part_in_flight (and blk_mq_in_flight) may be changed so that
it only returns one value.

This patch just refactors the code, there's no functional change.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jens Axboe

block: switch to per-cpu in-flight counters

2018-12-10T15:30:37+00:00

Now when part_round_stats is gone, we can switch to per-cpu in-flight
counters.

We use the local-atomic type local_t, so that if part_inc_in_flight or
part_dec_in_flight is reentrantly called from an interrupt, the value will
be correct.

The other counters could be corrupted due to reentrant interrupt, but the
corruption only results in slight counter skew - the in_flight counter
must be exact, so it needs local_t.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Jens Axboe