inode_detach_wb references the "main" bdi of the inode. With the
recent change to move the bdi from the request_queue to the gendisk
this causes a guaranteed use after free when using certain cgroup
configurations. The big itself is older through as any non-default
inode reference (e.g. an open file descriptor) could have injected
this use after free even before that.
Fixes: 52ebea749a ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks")
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Reported-by: syzbot <syzbot+1fb38bb7d3ce0fa3e1c4@syzkaller.appspotmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816122614.601358-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After patch 54efd50 (block: make generic_make_request handle
arbitrarily sized bios), the IO through io-throttle may be larger,
and these IOs may be further split into more small IOs. However,
IOPS throttle does not seem to be aware of this change, which
makes the calculation of IOPS of large IOs incomplete, resulting
in disk-side IOPS that does not meet expectations. Maybe we should
fix this problem.
We can reproduce it by set max_sectors_kb of disk to 128, set
blkio.write_iops_throttle to 100, run a dd instance inside blkio
and use iostat to watch IOPS:
dd if=/dev/zero of=/dev/sdb bs=1M count=1000 oflag=direct
As a result, without this change the average IOPS is 1995, with
this change the IOPS is 98.
Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/65869aaad05475797d63b4c3fed4f529febe3c26.1627876014.git.brookxu@tencent.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Partition scanning only happens on the whole device, so pass a
struct gendisk instead of the whole device block_device to the scanners.
This allows to simplify printing the device name in various places as the
disk name is available in disk->name.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://lore.kernel.org/r/20210810154512.1809898-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Fix the !CONFIG_BLOCK build after the recent cleanup.
Fixes: 5ed964f8e5 ("mm: hide laptop_mode_wb_timer entirely behind the BDI API")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When merging one bio to request, if they are discard IO and the queue
supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
because both block core and related drivers(nvme, virtio-blk) doesn't
handle mixed discard io merge(traditional IO merge together with
discard merge) well.
Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
so both blk-mq and drivers just need to handle multi-range discard.
Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Fixes: 2705dfb209 ("block: fix discard request merge")
Link: https://lore.kernel.org/r/20210729034226.1591070-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
device mapper is currently the only outlier that tries to call
register_disk after add_disk, leading to fairly inconsistent state
of these block layer data structures. Instead change device-mapper
to just register the gendisk later now that the holder mechanism
can cope with that.
Note that this introduces a user visible change: the dm kobject is
now only visible after the initial table has been loaded.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210804094147.459763-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
device mapper needs to register holders before it is ready to do I/O.
Currently it does so by registering the disk early, which can leave
the disk and queue in a weird half state where the queue is registered
with the disk, except for sysfs and the elevator. And this state has
been a bit promlematic before, and will get more so when sorting out
the responsibilities between the queue and the disk.
Support registering holders on an initialized but not registered disk
instead by delaying the sysfs registration until the disk is registered.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210804094147.459763-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the block holder code into a separate file as it is not in any way
related to the other block_dev.c code, and add a new selectable config
option for it so that we don't have to build it without any remapped
drivers selected.
The Kconfig symbol contains a _DEPRECATED suffix to match the comments
added in commit 49731baa41
("block: restore multiple bd_link_disk_holder() support").
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210804094147.459763-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We noticed that the user interface of Android devices becomes very slow
under memory pressure. This is because Android uses the zram driver on top
of the loop driver for swapping, because under memory pressure the swap
code alternates reads and writes quickly, because mq-deadline is the
default scheduler for loop devices and because mq-deadline delays writes by
five seconds for such a workload with default settings. Fix this by making
the kernel select I/O scheduler 'none' from inside add_disk() for loop
devices. This default can be overridden at any time from user space,
e.g. via a udev rule. This approach has an advantage compared to changing
the I/O scheduler from userspace from 'mq-deadline' into 'none', namely
that synchronize_rcu() does not get called.
This patch changes the default I/O scheduler for loop devices from
'mq-deadline' into 'none'.
Additionally, this patch reduces the Android boot time on my test setup
with 0.5 seconds compared to configuring the loop I/O scheduler from user
space.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Martijn Coenen <maco@android.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20210805174200.3250718-3-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
