Commit Graph

171 Commits

Author SHA1 Message Date
Christoph Hellwig fb5d1d389c ubd: open the backing files in ubd_add
Opening the backing device only when the block device is opened is
a bit weird as no one configures block devices to not use them.
Opend them at add time, close them at remove time and remove the
now superflous opened counter as remove can simply check for
disk_openers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20240222072417.3773131-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-27 14:21:15 -07:00
Christoph Hellwig f3c17dcc43 ubd: remove the queue pointer in struct ubd
No need for it now, everything goes through the gendisk.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20240222072417.3773131-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-27 14:21:15 -07:00
Christoph Hellwig 5e4e1ff820 ubd: move set_disk_ro to ubd_add
No need to delay this until open time.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20240222072417.3773131-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-27 14:21:15 -07:00
Christoph Hellwig 58ebe3e748 ubd: move setting the variable queue limits to ubd_add
No reason to delay this until open time.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20240222072417.3773131-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-27 14:21:15 -07:00
Christoph Hellwig b8b364d2af ubd: move setting the nonrot flag to ubd_add
No reason to delay this until open time.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20240222072417.3773131-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-27 14:21:15 -07:00
Christoph Hellwig 0267e9cac6 ubd: remove ubd_disk_register
Fold it into the only caller to remove lots of references to the
global ubd_devs array.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20240222072417.3773131-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-27 14:21:15 -07:00
Christoph Hellwig 32621ad7a7 ubd: remove the ubd_gendisk array
And add a disk pointer to the ubd structure instead to keep all
the per-device information together.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20240222072417.3773131-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-27 14:21:15 -07:00
Christoph Hellwig 5d6789ce33 ubd: pass queue_limits to blk_mq_alloc_disk
Pass the few limits ubd imposes directly to blk_mq_alloc_disk instead
of setting them one at a time.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240215070300.2200308-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-19 16:59:31 -07:00
Christoph Hellwig 27e32cd23f block: pass a queue_limits argument to blk_mq_alloc_disk
Pass a queue_limits to blk_mq_alloc_disk and apply it if non-NULL.  This
will allow allocating queues with valid queue limits instead of setting
the values one at a time later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20240213073425.1621680-11-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-02-13 08:56:59 -07:00
Christoph Hellwig 599d9d4eab ubd: use the default discard granularity
The discard granularity now defaults to a single sector, so don't set
that value explicitly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20231228075545.362768-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-12-29 08:44:12 -07:00
Christoph Hellwig 05bdb99653 block: replace fmode_t with a block-specific type for block open flags
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 <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com>		[rnbd]
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-06-12 08:04:05 -06:00
Christoph Hellwig bd6abfc8e7 ubd: remove commented out code in ubd_open
This code has been dead forever, make sure it doesn't show up in code
searches.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20230608110258.189493-25-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-06-12 08:04:04 -06:00
Christoph Hellwig ae220766d8 block: remove the unused mode argument to ->release
The mode argument to the ->release block_device_operation is never used,
so remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Jack Wang <jinpu.wang@ionos.com>			[rnbd]
Link: https://lore.kernel.org/r/20230608110258.189493-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-06-12 08:04:04 -06:00
Christoph Hellwig d32e2bf837 block: pass a gendisk to ->open
->open is only called on the whole device.  Make that explicit by
passing a gendisk instead of the block_device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Jack Wang <jinpu.wang@ionos.com>		[rnbd]
Link: https://lore.kernel.org/r/20230608110258.189493-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-06-12 08:04:04 -06:00
Xin Gao 4dc5a32831 um: Do not initialise statics to 0.
do not initialise statics to 0.

Signed-off-by: Xin Gao <gaoxin@cdjrlc.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2022-09-19 23:10:07 +02:00
Bart Van Assche 7ee1de6e27 um: Use enum req_op where appropriate
Improve static type checking by using type enum req_op instead of int where
appropriate.

Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20220714180729.1065367-21-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-14 12:14:31 -06:00
Christoph Hellwig 8b9ab62662 block: remove blk_cleanup_disk
blk_cleanup_disk is nothing but a trivial wrapper for put_disk now,
so remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20220619060552.1850436-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-06-28 06:33:15 -06:00
Christoph Hellwig 07c6e92a84 ubd: don't set the discard_alignment queue limit
The discard_alignment queue limit is named a bit misleading means the
offset into the block device at which the discard granularity starts.
Setting it to the discard granularity as done by ubd is mostly harmless
but also useless.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20220418045314.360785-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-05-03 10:38:50 -06:00
Christoph Hellwig 70200574cc block: remove QUEUE_FLAG_DISCARD
Just use a non-zero max_discard_sectors as an indicator for discard
support, similar to what is done for write zeroes.

The only places where needs special attention is the RAID5 driver,
which must clear discard support for security reasons by default,
even if the default stacking rules would allow for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> [drbd]
Acked-by: Jan Höppner <hoeppner@linux.ibm.com> [s390]
Acked-by: Coly Li <colyli@suse.de> [bcache]
Acked-by: David Sterba <dsterba@suse.com> [btrfs]
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220415045258.199825-25-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-04-17 19:49:59 -06:00
Frédéric Danis d2a0a616ab um: Fix WRITE_ZEROES in the UBD Driver
Call to fallocate with FALLOC_FL_PUNCH_HOLE on a device backed by a sparse
file can end up by missing data, zeroes data range, if the underlying file
is used with a tool like bmaptool which will referenced only used spaces.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2022-03-11 10:46:34 +01:00
Luis Chamberlain 66638f163a um/drivers/ubd_kern: add error handling support for add_disk()
We never checked for errors on add_disk() as this function
returned void. Now that this is fixed, use the shiny new
error handling.

ubd_disk_register() never returned an error, so just fix
that now and let the caller handle the error condition.

Reviewed-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20211015233028.2167651-8-mcgrof@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-21 09:00:56 -06:00
Christoph Hellwig b81e0c2372 block: drop unused includes in <linux/genhd.h>
Drop various include not actually used in genhd.h itself, and
move the remaning includes closer together.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18 06:17:02 -06:00
Christoph Hellwig 25d84545be ubd: use bvec_virt
Use bvec_virt instead of open coding it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Link: https://lore.kernel.org/r/20210804095634.460779-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-16 10:50:33 -06:00
Linus Torvalds a022f7d575 block-5.14-2021-07-08
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Merge tag 'block-5.14-2021-07-08' of git://git.kernel.dk/linux-block

Pull more block updates from Jens Axboe:
 "A combination of changes that ended up depending on both the driver
  and core branch (and/or the IDE removal), and a few late arriving
  fixes. In detail:

   - Fix io ticks wrap-around issue (Chunguang)

   - nvme-tcp sock locking fix (Maurizio)

   - s390-dasd fixes (Kees, Christoph)

   - blk_execute_rq polling support (Keith)

   - blk-cgroup RCU iteration fix (Yu)

   - nbd backend ID addition (Prasanna)

   - Partition deletion fix (Yufen)

   - Use blk_mq_alloc_disk for mmc, mtip32xx, ubd (Christoph)

   - Removal of now dead block request types due to IDE removal
     (Christoph)

   - Loop probing and control device cleanups (Christoph)

   - Device uevent fix (Christoph)

   - Misc cleanups/fixes (Tetsuo, Christoph)"

* tag 'block-5.14-2021-07-08' of git://git.kernel.dk/linux-block: (34 commits)
  blk-cgroup: prevent rcu_sched detected stalls warnings while iterating blkgs
  block: fix the problem of io_ticks becoming smaller
  nvme-tcp: can't set sk_user_data without write_lock
  loop: remove unused variable in loop_set_status()
  block: remove the bdgrab in blk_drop_partitions
  block: grab a device refcount in disk_uevent
  s390/dasd: Avoid field over-reading memcpy()
  dasd: unexport dasd_set_target_state
  block: check disk exist before trying to add partition
  ubd: remove dead code in ubd_setup_common
  nvme: use return value from blk_execute_rq()
  block: return errors from blk_execute_rq()
  nvme: use blk_execute_rq() for passthrough commands
  block: support polling through blk_execute_rq
  block: remove REQ_OP_SCSI_{IN,OUT}
  block: mark blk_mq_init_queue_data static
  loop: rewrite loop_exit using idr_for_each_entry
  loop: split loop_lookup
  loop: don't allow deleting an unspecified loop device
  loop: move loop_ctl_mutex locking into loop_add
  ...
2021-07-09 12:05:33 -07:00
Christoph Hellwig efee99e68e ubd: remove dead code in ubd_setup_common
Remove some leftovers of the fake major number parsing that cause
complains from some compilers.

Fixes: 2933a1b2c6f3 ("ubd: remove the code to register as the legacy IDE driver")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210628093937.1325608-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30 15:35:45 -06:00
Christoph Hellwig 35efb594c3 ubd: use blk_mq_alloc_disk and blk_cleanup_disk
Use blk_mq_alloc_disk and blk_cleanup_disk to simplify the gendisk and
request_queue allocation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210614060759.3965724-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30 15:34:04 -06:00
Christoph Hellwig 7eb90f7e90 ubd: remove the code to register as the legacy IDE driver
With the legacy IDE driver long deprecated, and modern userspace being
much more flexible about dev_t assignments there is no reason to fake
a registration as the legacy IDE driver in ubd.  This registeration
is a little problematic as it registers the same request_queue for
multiple gendisks, so just remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Link: https://lore.kernel.org/r/20210614060759.3965724-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30 15:34:04 -06:00
YiFei Zhu 558f9b2f94 um: Fix stack pointer alignment
GCC assumes that stack is aligned to 16-byte on call sites [1].
Since GCC 8, GCC began using 16-byte aligned SSE instructions to
implement assignments to structs on stack. When
CC_OPTIMIZE_FOR_PERFORMANCE is enabled, this affects
os-Linux/sigio.c, write_sigio_thread:

  struct pollfds *fds, tmp;
  tmp = current_poll;

Note that struct pollfds is exactly 16 bytes in size.
GCC 8+ generates assembly similar to:

  movdqa (%rdi),%xmm0
  movaps %xmm0,-0x50(%rbp)

This is an issue, because movaps will #GP if -0x50(%rbp) is not
aligned to 16 bytes [2], and how rbp gets assigned to is via glibc
clone thread_start, then function prologue, going though execution
trace similar to (showing only relevant instructions):

  sub    $0x10,%rsi
  mov    %rcx,0x8(%rsi)
  mov    %rdi,(%rsi)
  syscall
  pop    %rax
  pop    %rdi
  callq  *%rax
  push   %rbp
  mov    %rsp,%rbp

The stack pointer always points to the topmost element on stack,
rather then the space right above the topmost. On push, the
pointer decrements first before writing to the memory pointed to
by it. Therefore, there is no need to have the stack pointer
pointer always point to valid memory unless the stack is poped;
so the `- sizeof(void *)` in the code is unnecessary.

On the other hand, glibc reserves the 16 bytes it needs on stack
and pops itself, so by the call instruction the stack pointer
is exactly the caller-supplied sp. It then push the 16 bytes of
the return address and the saved stack pointer, so the base
pointer will be 16-byte aligned if and only if the caller
supplied sp is 16-byte aligned. Therefore, the caller must supply
a 16-byte aligned pointer, which `stack + UM_KERN_PAGE_SIZE`
already satisfies.

On a side note, musl is unaffected by this issue because it forces
16 byte alignment via `and $-16,%rsi` in its clone wrapper.
Similarly, glibc i386 is also unaffected because it has
`andl $0xfffffff0, %ecx`.

To reproduce this bug, enable CONFIG_UML_RTC and
CC_OPTIMIZE_FOR_PERFORMANCE. uml_rtc will call
add_sigio_fd which will then cause write_sigio_thread to either go
into segfault loop or panic with "Segfault with no mm".

Similarly, signal stacks will be aligned by the host kernel upon
signal delivery. `- sizeof(void *)` to sigaltstack is
unconventional and extraneous.

On a related note, initialization of longjmp buffers do require
`- sizeof(void *)`. This is to account for the return address
that would have been pushed to the stack at the call site.

The reason for uml to respect 16-byte alignment, rather than
telling GCC to assume 8-byte alignment like the host kernel since
commit d9b0cde91c ("x86-64, gcc: Use
-mpreferred-stack-boundary=3 if supported"), is because uml links
against libc. There is no reason to assume libc is also compiled
with that flag and assumes 8-byte alignment rather than 16-byte.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838
[2] https://c9x.me/x86/html/file_module_x86_id_180.html

Signed-off-by: YiFei Zhu <zhuyifei1999@gmail.com>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
2021-06-17 22:08:31 +02:00
Johannes Berg 2fcb4090cd Revert "um: allocate a guard page to helper threads"
This reverts commit ef4459a6da ("um: allocate a guard page to
helper threads"), it's broken in multiple ways:

 1) the free no longer matches the alloc; and

 2) more importantly, the set_memory_ro() causes allocation of
    page tables for the normal memory that doesn't have any,
    and that later causes corruption and crashes (usually but
    not always in vfree()).

We could fix the first bug and use vmalloc() to work around the
second, but set_memory_ro() actually doesn't do anything either
so I'll just revert that as well.

Reported-by: Benjamin Berg <benjamin@sipsolutions.net>
Fixes: ef4459a6da ("um: allocate a guard page to helper threads")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2021-01-26 22:11:38 +01:00
Hajime Tazaki 94c41b3a7c um: ubd: fix command line handling of ubd
This commit fixes a regression to handle command line parameters of ubd.
With a simple line "./linux ubd0="./disk-ext4.img", it fails at
ubd_setup_common().  The commit adds additional checks to the variables
in order to properly parse the paremeters which previously worked.

Fixes: ef3ba87cb7 ("um: ubd: Set device serial attribute from cmdline")
Cc: Christopher Obbard <chris.obbard@collabora.com>
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Acked-by: Christopher Obbard <chris.obbard@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2021-01-26 22:10:44 +01:00
Johannes Berg ef4459a6da um: allocate a guard page to helper threads
We've been running into stack overflows in helper threads
corrupting memory (e.g. because somebody put printf() or
os_info() there), so to avoid those causing hard-to-debug
issues later on, allocate a guard page for helper thread
stacks and mark it read-only.

Unfortunately, the crash dump at that point is useless as
the stack tracer will try to backtrace the *kernel* thread,
not the helper thread, but at least we don't survive to a
random issue caused by corruption.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2020-12-13 22:38:06 +01:00
Johannes Berg 36d46a5907 um: Support dynamic IRQ allocation
It's cumbersome and error-prone to keep adding fixed IRQ numbers,
and for proper device wakeup support for the virtio/vhost-user
support we need to have different IRQs for each device. Even if
in theory two IRQs (with and without wake) might be sufficient,
it's much easier to reason about it when we have dynamic number
assignment. It also makes it easier to add new devices that may
dynamically exist or depending on the configuration, etc.

Add support for this, up to 64 IRQs (the same limit as epoll FDs
we have right now). Since it's not easy to port all the existing
places to dynamic allocation (some data is statically initialized)
keep the low numbers are reserved for the existing hard-coded IRQ
numbers.

Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2020-12-13 22:22:08 +01:00
Christopher Obbard ef3ba87cb7 um: ubd: Set device serial attribute from cmdline
Adds the ability to set the UBD device serial number from the
commandline, disabling the serial number functionality by default.

In some cases it may be useful to set a serial to the UBD device, such
that downstream users (i.e. udev) can use this information to better
describe the hardware to the user from the UML cmdline. In our case we
use this parameter to create some entries under /dev/disk/by-ubd-id/
for each of the UBD devices passed through the UML cmdline.

Signed-off-by: Christopher Obbard <chris.obbard@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2020-12-13 22:22:01 +01:00
Gabriel Krisman Bertazi fc6b6a872d um: ubd: Submit all data segments atomically
Internally, UBD treats each physical IO segment as a separate command to
be submitted in the execution pipe.  If the pipe returns a transient
error after a few segments have already been written, UBD will tell the
block layer to requeue the request, but there is no way to reclaim the
segments already submitted.  When a new attempt to dispatch the request
is done, those segments already submitted will get duplicated, causing
the WARN_ON below in the best case, and potentially data corruption.

In my system, running a UML instance with 2GB of RAM and a 50M UBD disk,
I can reproduce the WARN_ON by simply running mkfs.fvat against the
disk on a freshly booted system.

There are a few ways to around this, like reducing the pressure on
the pipe by reducing the queue depth, which almost eliminates the
occurrence of the problem, increasing the pipe buffer size on the host
system, or by limiting the request to one physical segment, which causes
the block layer to submit way more requests to resolve a single
operation.

Instead, this patch modifies the format of a UBD command, such that all
segments are sent through a single element in the communication pipe,
turning the command submission atomic from the point of view of the
block layer.  The new format has a variable size, depending on the
number of elements, and looks like this:

+------------+-----------+-----------+------------
| cmd_header | segment 0 | segment 1 | segment ...
+------------+-----------+-----------+------------

With this format, we push a pointer to cmd_header in the submission
pipe.

This has the advantage of reducing the memory footprint of executing a
single request, since it allow us to merge some fields in the header.
It is possible to reduce even further each segment memory footprint, by
merging bitmap_words and cow_offset, for instance, but this is not the
focus of this patch and is left as future work.  One issue with the
patch is that for a big number of segments, we now perform one big
memory allocation instead of multiple small ones, but I wasn't able to
trigger any real issues or -ENOMEM because of this change, that wouldn't
be reproduced otherwise.

This was tested using fio with the verify-crc32 option, and by running
an ext4 filesystem over this UBD device.

The original WARN_ON was:

------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at lib/refcount.c:28 refcount_warn_saturate+0x13f/0x141
refcount_t: underflow; use-after-free.
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.5.0-rc6-00002-g2a5bb2cf75c8 #346
Stack:
 6084eed0 6063dc77 00000009 6084ef60
 00000000 604b8d9f 6084eee0 6063dcbc
 6084ef40 6006ab8d e013d780 1c00000000
Call Trace:
 [<600a0c1c>] ? printk+0x0/0x94
 [<6004a888>] show_stack+0x13b/0x155
 [<6063dc77>] ? dump_stack_print_info+0xdf/0xe8
 [<604b8d9f>] ? refcount_warn_saturate+0x13f/0x141
 [<6063dcbc>] dump_stack+0x2a/0x2c
 [<6006ab8d>] __warn+0x107/0x134
 [<6008da6c>] ? wake_up_process+0x17/0x19
 [<60487628>] ? blk_queue_max_discard_sectors+0x0/0xd
 [<6006b05f>] warn_slowpath_fmt+0xd1/0xdf
 [<6006af8e>] ? warn_slowpath_fmt+0x0/0xdf
 [<600acc14>] ? raw_read_seqcount_begin.constprop.0+0x0/0x15
 [<600619ae>] ? os_nsecs+0x1d/0x2b
 [<604b8d9f>] refcount_warn_saturate+0x13f/0x141
 [<6048bc8f>] refcount_sub_and_test.constprop.0+0x2f/0x37
 [<6048c8de>] blk_mq_free_request+0xf1/0x10d
 [<6048ca06>] __blk_mq_end_request+0x10c/0x114
 [<6005ac0f>] ubd_intr+0xb5/0x169
 [<600a1a37>] __handle_irq_event_percpu+0x6b/0x17e
 [<600a1b70>] handle_irq_event_percpu+0x26/0x69
 [<600a1bd9>] handle_irq_event+0x26/0x34
 [<600a1bb3>] ? handle_irq_event+0x0/0x34
 [<600a5186>] ? unmask_irq+0x0/0x37
 [<600a57e6>] handle_edge_irq+0xbc/0xd6
 [<600a131a>] generic_handle_irq+0x21/0x29
 [<60048f6e>] do_IRQ+0x39/0x54
 [...]
---[ end trace c6e7444e55386c0f ]---

Cc: Christopher Obbard <chris.obbard@collabora.com>
Reported-by: Martyn Welch <martyn@collabora.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Tested-by: Christopher Obbard <chris.obbard@collabora.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2020-12-13 22:21:55 +01:00
Gabriel Krisman Bertazi e355b2f55e um: ubd: Retry buffer read on any kind of error
Should bulk_req_safe_read return an error, we want to retry the read,
otherwise, even though no IO will be done, os_write_file might still end
up writing garbage to the pipe.

Cc: Martyn Welch <martyn.welch@collabora.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2020-03-29 23:21:37 +02:00
Gabriel Krisman Bertazi 6e682d53fc um: ubd: Prevent buffer overrun on command completion
On the hypervisor side, when completing commands and the pipe is full,
we retry writing only the entries that failed, by offsetting
io_req_buffer, but we don't reduce the number of bytes written, which
can cause a buffer overrun of io_req_buffer, and write garbage to the
pipe.

Cc: Martyn Welch <martyn.welch@collabora.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2020-03-29 23:21:33 +02:00
Linus Torvalds 33c84e89ab SCSI misc on 20200129
This series is slightly unusual because it includes Arnd's compat
 ioctl tree here:
 
 1c46a2cf2d Merge tag 'block-ioctl-cleanup-5.6' into 5.6/scsi-queue
 
 Excluding Arnd's changes, this is mostly an update of the usual
 drivers: megaraid_sas, mpt3sas, qla2xxx, ufs, lpfc, hisi_sas.  There
 are a couple of core and base updates around error propagation and
 atomicity in the attribute container base we use for the SCSI
 transport classes.  The rest is minor changes and updates.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
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Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI updates from James Bottomley:
 "This series is slightly unusual because it includes Arnd's compat
  ioctl tree here:

    1c46a2cf2d Merge tag 'block-ioctl-cleanup-5.6' into 5.6/scsi-queue

  Excluding Arnd's changes, this is mostly an update of the usual
  drivers: megaraid_sas, mpt3sas, qla2xxx, ufs, lpfc, hisi_sas.

  There are a couple of core and base updates around error propagation
  and atomicity in the attribute container base we use for the SCSI
  transport classes.

  The rest is minor changes and updates"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (149 commits)
  scsi: hisi_sas: Rename hisi_sas_cq.pci_irq_mask
  scsi: hisi_sas: Add prints for v3 hw interrupt converge and automatic affinity
  scsi: hisi_sas: Modify the file permissions of trigger_dump to write only
  scsi: hisi_sas: Replace magic number when handle channel interrupt
  scsi: hisi_sas: replace spin_lock_irqsave/spin_unlock_restore with spin_lock/spin_unlock
  scsi: hisi_sas: use threaded irq to process CQ interrupts
  scsi: ufs: Use UFS device indicated maximum LU number
  scsi: ufs: Add max_lu_supported in struct ufs_dev_info
  scsi: ufs: Delete is_init_prefetch from struct ufs_hba
  scsi: ufs: Inline two functions into their callers
  scsi: ufs: Move ufshcd_get_max_pwr_mode() to ufshcd_device_params_init()
  scsi: ufs: Split ufshcd_probe_hba() based on its called flow
  scsi: ufs: Delete struct ufs_dev_desc
  scsi: ufs: Fix ufshcd_probe_hba() reture value in case ufshcd_scsi_add_wlus() fails
  scsi: ufs-mediatek: enable low-power mode for hibern8 state
  scsi: ufs: export some functions for vendor usage
  scsi: ufs-mediatek: add dbg_register_dump implementation
  scsi: qla2xxx: Fix a NULL pointer dereference in an error path
  scsi: qla1280: Make checking for 64bit support consistent
  scsi: megaraid_sas: Update driver version to 07.713.01.00-rc1
  ...
2020-01-29 18:16:16 -08:00
Arnd Bergmann ab0cf1e425 compat_ioctl: ubd, aoe: use blkdev_compat_ptr_ioctl
These drivers implement the HDIO_GET_IDENTITY and CDROMVOLREAD ioctl
commands, which are compatible between 32-bit and 64-bit user space and
traditionally handled by compat_blkdev_driver_ioctl().

As a prerequisite to removing that function, make both drivers use
blkdev_compat_ptr_ioctl() as their .compat_ioctl callback.

Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2020-01-03 09:33:02 +01:00
Arnd Bergmann 853bc0ab34 um: ubd: use 64-bit time_t where possible
The ubd code suffers from a possible y2038 overflow on 32-bit
architectures, both for the cow header and the os_file_modtime()
function.

Replace time_t with time64_t to extend the ubd_kern side as much
as possible.

Whether this makes a difference for the user side depends on
the host libc implementation that may use either 32-bit or 64-bit
time_t.

For the cow file format, the header contains an unsigned 32-bit
timestamp, which is good until y2106, passing this through a
'long long' gives us a consistent interpretation between 32-bit
and 64-bit um kernels.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2019-12-18 18:07:31 +01:00
Anton Ivanov d848074b2f um-ubd: Entrust re-queue to the upper layers
Fixes crashes due to ubd requeue logic conflicting with the block-mq
logic. Crash is reproducible in 5.0 - 5.3.

Fixes: 53766defb8 ("um: Clean-up command processing in UML UBD driver")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-29 10:07:41 -06:00
Alex Dewar dbddf429dc um: Add SPDX headers for files in arch/um/drivers
Convert files to use SPDX header. All files are licensed under the GPLv2.

Signed-off-by: Alex Dewar <alex.dewar@gmx.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
2019-09-15 21:37:16 +02:00
Daniel Walter 9ca55299f2 um: Do not unlock mutex that is not hold.
Return error instead of trying to unlock a mutex that is not hold.

Signed-off-by: Daniel Walter <dwalter@google.com>
Reviewed-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2019-05-07 23:18:28 +02:00
Anton Ivanov aea05eb56e um: Fix for a possible OOPS in ubd initialization
If the ubd device failed to allocate a queue during
initialization it tried call blk_cleanup_queue resulting
in an oops.

This patch simplifies the cleanup logic and ensures that
blk_queue_cleanup is called only if there is a valid queue.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2019-03-06 22:39:18 +01:00
Anton Ivanov 940b241d90 um: Remove obsolete reenable_XX calls
reenable_fd has been a NOP since the introduction of the EPOLL
based interrupt controller.
reenable_channel() is no longer needed as the flow control is
now handled via the write IRQs on the channel.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2018-12-27 22:48:35 +01:00
Anton Ivanov 50109b5a03 um: Add support for DISCARD in the UBD Driver
Support for DISCARD and WRITE_ZEROES in the ubd driver using
fallocate.

DISCARD is enabled by default and can be disabled using a new
UBD command line flag.

If the underlying fs on which the UBD image is stored does not
support DISCARD the support for both DISCARD and WRITE_ZEROES
is turned off.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2018-12-27 22:48:20 +01:00
Anton Ivanov a41421edb9 um: Remove unsafe printks from the io thread
Printk out of the io thread has been proven to be unsafe. This
is not surprising as the thread is part of the UML hypervisor
code. It is not supposed to invoke any kernel code/resources.

It is necesssary to pass the error to the block IO layer and let it

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2018-12-27 22:48:20 +01:00
Anton Ivanov 53766defb8 um: Clean-up command processing in UML UBD driver
Clean-up command processing and return BLK_STS_NOTSUP for
uknown commands.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2018-12-27 22:48:20 +01:00
Anton Ivanov a43c83161a um: Switch to block-mq constants in the UML UBD driver
Switch to block mq-constants for both commands, error codes and
various computations.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2018-12-27 22:48:20 +01:00
Anton Ivanov 0033dfd92a ubd: fix missing initialization of io_req
The SYNC path doesn't initialize io_req->error, which can cause
random errors. Before the conversion to blk-mq, we always
completed requests with BLK_STS_OK status, but now we actually
look at the error field and this issue becomes apparent.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>

[axboe: fixed up commit message to explain what is actually going on]

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-08 06:16:09 -07:00
Jens Axboe 6961cd4d0f ubd: fix missing lock around request issue
We need to hold the device lock (and disable interrupts) while
writing new commands, or we could be interrupted while that
is happening and read invalid requests in the completion path.

Fixes: 4e6da0fe80 ("um: Convert ubd driver to blk-mq")
Tested-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 14:34:05 -07:00