linux-stable.git/drivers/block/loop.c, branch linux-5.10.y

block: remove the update_bdev parameter to set_capacity_revalidate_and_notify

2025-02-01T17:22:24+00:00

[ Upstream commit 449f4ec9892ebc2f37a7eae6d97db2cf7c65e09a ]

The update_bdev argument is always set to true, so remove it.  Also
rename the function to the slighly less verbose set_capacity_and_notify,
as propagating the disk size to the block device isn't really
revalidation.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Reviewed-by: Petr Vorel 
Signed-off-by: Jens Axboe 
Stable-dep-of: 74363ec674cb ("zram: fix uninitialized ZRAM not releasing backing device")
Signed-off-by: Sasha Levin

loop: let set_capacity_revalidate_and_notify update the bdev size

2025-02-01T17:22:24+00:00

[ Upstream commit 3b4f85d02a4bd85cbea999a064235a47694bbb7b ]

There is no good reason to call revalidate_disk_size separately.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Jens Axboe 
Stable-dep-of: 74363ec674cb ("zram: fix uninitialized ZRAM not releasing backing device")
Signed-off-by: Sasha Levin

loop: Select I/O scheduler 'none' from inside add_disk()

2023-08-11T09:57:46+00:00

commit 2112f5c1330a671fa852051d85cb9eadc05d7eb7 upstream.

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 
Cc: Ming Lei 
Cc: Tetsuo Handa 
Cc: Martijn Coenen 
Cc: Jaegeuk Kim 
Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20210805174200.3250718-3-bvanassche@acm.org
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: loop_set_status_from_info() check before assignment

2023-03-11T15:40:14+00:00

[ Upstream commit 9f6ad5d533d1c71e51bdd06a5712c4fbc8768dfa ]

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 
Signed-off-by: Sasha Levin

loop: Check for overflow while configuring loop

2022-08-31T15:15:22+00:00

commit c490a0b5a4f36da3918181a8acdc6991d967c5f3 upstream.

The userspace can configure a loop using an ioctl call, wherein
a configuration of type loop_config is passed (see lo_ioctl()'s
case on line 1550 of drivers/block/loop.c). This proceeds to call
loop_configure() which in turn calls loop_set_status_from_info()
(see line 1050 of loop.c), passing &config->info which is of type
loop_info64*. This function then sets the appropriate values, like
the offset.

loop_device has lo_offset of type loff_t (see line 52 of loop.c),
which is typdef-chained to long long, whereas loop_info64 has
lo_offset of type __u64 (see line 56 of include/uapi/linux/loop.h).

The function directly copies offset from info to the device as
follows (See line 980 of loop.c):
	lo->lo_offset = info->lo_offset;

This results in an overflow, which triggers a warning in iomap_iter()
due to a call to iomap_iter_done() which has:
	WARN_ON_ONCE(iter->iomap.offset > iter->pos);

Thus, check for negative value during loop_set_status_from_info().

Bug report: https://syzkaller.appspot.com/bug?id=c620fe14aac810396d3c3edc9ad73848bf69a29e

Reported-and-tested-by: syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Reviewed-by: Matthew Wilcox (Oracle) 
Signed-off-by: Siddh Raman Pant 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20220823160810.181275-1-code@siddh.me
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: use sysfs_emit() in the sysfs xxx show()

2022-04-08T12:40:31+00:00

[ Upstream commit b27824d31f09ea7b4a6ba2c1b18bd328df3e8bed ]

sprintf does not know the PAGE_SIZE maximum of the temporary buffer
used for outputting sysfs content and it's possible to overrun the
PAGE_SIZE buffer length.

Use a generic sysfs_emit function that knows the size of the
temporary buffer and ensures that no overrun is done for offset
attribute in
loop_attr_[offset|sizelimit|autoclear|partscan|dio]_show() callbacks.

Signed-off-by: Chaitanya Kulkarni 
Reviewed-by: Himanshu Madhani 
Link: https://lore.kernel.org/r/20220215213310.7264-2-kch@nvidia.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

loop: Use blk_validate_block_size() to validate block size

2021-11-21T12:46:35+00:00

commit af3c570fb0df422b4906ebd11c1bf363d89961d5 upstream.

Remove loop_validate_block_size() and use the block layer helper
to validate block size.

Signed-off-by: Xie Yongji 
Link: https://lore.kernel.org/r/20211026144015.188-4-xieyongji@bytedance.com
Signed-off-by: Jens Axboe 
Cc: Tadeusz Struk 
Signed-off-by: Greg Kroah-Hartman

loop: fix I/O error on fsync() in detached loop devices

2021-07-19T07:44:55+00:00

commit 4ceddce55eb35d15b0f87f5dcf6f0058fd15d3a4 upstream.

There's an I/O error on fsync() in a detached loop device
if it has been previously attached.

The issue is write cache is enabled in the attach path in
loop_configure() but it isn't disabled in the detach path;
thus it remains enabled in the block device regardless of
whether it is attached or not.

Now fsync() can get an I/O request that will just be failed
later in loop_queue_rq() as device's state is not 'Lo_bound'.

So, disable write cache in the detach path.

Do so based on the queue flag, not the loop device flag for
read-only (used to enable) as the queue flag can be changed
via sysfs even on read-only loop devices (e.g., losetup -r.)

Test-case:

    # DEV=/dev/loop7

    # IMG=/tmp/image
    # truncate --size 1M $IMG

    # losetup $DEV $IMG
    # losetup -d $DEV

Before:

    # strace -e fsync parted -s $DEV print 2>&1 | grep fsync
    fsync(3)                                = -1 EIO (Input/output error)
    Warning: Error fsyncing/closing /dev/loop7: Input/output error
    [  982.529929] blk_update_request: I/O error, dev loop7, sector 0 op 0x1:(WRITE) flags 0x800 phys_seg 0 prio class 0

After:

    # strace -e fsync parted -s $DEV print 2>&1 | grep fsync
    fsync(3)                                = 0

Co-developed-by: Eric Desrochers 
Signed-off-by: Eric Desrochers 
Signed-off-by: Mauricio Faria de Oliveira 
Tested-by: Gabriel Krisman Bertazi 
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe 
Signed-off-by: Hanjun Guo 
Signed-off-by: Greg Kroah-Hartman

loop: Fix missing discard support when using LOOP_CONFIGURE

2021-07-14T14:55:46+00:00

commit 2b9ac22b12a266eb4fec246a07b504dd4983b16b upstream.

Without calling loop_config_discard() the discard flag and parameters
aren't set/updated for the loop device and worst-case they could
indicate discard support when it isn't the case (ex: if the
LOOP_SET_STATUS ioctl was used with a different file prior to
LOOP_CONFIGURE).

Cc:  # 5.8.x-
Fixes: 3448914e8cc5 ("loop: Add LOOP_CONFIGURE ioctl")
Signed-off-by: Kristian Klausen 
Link: https://lore.kernel.org/r/20210618115157.31452-1-kristian@klausen.dk
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: Fix occasional uevent drop

2020-11-12T20:59:04+00:00

Commit 716ad0986cbd ("loop: Switch to set_capacity_revalidate_and_notify")
causes an occasional drop of loop device uevent, which are no longer
triggered in loop_set_size() but in a different part of code.

Bug is reproducible with LTP test uevent01 [1]:

i=0; while true; do
    i=$((i+1)); echo "== $i =="
    lsmod |grep -q loop && rmmod -f loop
    ./uevent01 || break
done

Put back triggering through code called in loop_set_size().

Fix required to add yet another parameter to
set_capacity_revalidate_and_notify().

[1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/uevents/uevent01.c

[hch: rebased on a different change to the prototype of
 set_capacity_revalidate_and_notify]

Cc: stable@vger.kernel.org # v5.9
Fixes: 716ad0986cbd ("loop: Switch to set_capacity_revalidate_and_notify")
Reported-by: 
Signed-off-by: Petr Vorel 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe