Commit Graph

390 Commits

Author SHA1 Message Date
Tetsuo Handa dfbb3409b2 block: genhd: don't call blkdev_show() with major_names_lock held
If CONFIG_BLK_DEV_LOOP && CONFIG_MTD (at least; there might be other
combinations), lockdep complains circular locking dependency at
__loop_clr_fd(), for major_names_lock serves as a locking dependency
aggregating hub across multiple block modules.

 ======================================================
 WARNING: possible circular locking dependency detected
 5.14.0+ #757 Tainted: G            E
 ------------------------------------------------------
 systemd-udevd/7568 is trying to acquire lock:
 ffff88800f334d48 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x70/0x560

 but task is already holding lock:
 ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #6 (&lo->lo_mutex){+.+.}-{3:3}:
        lock_acquire+0xbe/0x1f0
        __mutex_lock_common+0xb6/0xe10
        mutex_lock_killable_nested+0x17/0x20
        lo_open+0x23/0x50 [loop]
        blkdev_get_by_dev+0x199/0x540
        blkdev_open+0x58/0x90
        do_dentry_open+0x144/0x3a0
        path_openat+0xa57/0xda0
        do_filp_open+0x9f/0x140
        do_sys_openat2+0x71/0x150
        __x64_sys_openat+0x78/0xa0
        do_syscall_64+0x3d/0xb0
        entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> #5 (&disk->open_mutex){+.+.}-{3:3}:
        lock_acquire+0xbe/0x1f0
        __mutex_lock_common+0xb6/0xe10
        mutex_lock_nested+0x17/0x20
        bd_register_pending_holders+0x20/0x100
        device_add_disk+0x1ae/0x390
        loop_add+0x29c/0x2d0 [loop]
        blk_request_module+0x5a/0xb0
        blkdev_get_no_open+0x27/0xa0
        blkdev_get_by_dev+0x5f/0x540
        blkdev_open+0x58/0x90
        do_dentry_open+0x144/0x3a0
        path_openat+0xa57/0xda0
        do_filp_open+0x9f/0x140
        do_sys_openat2+0x71/0x150
        __x64_sys_openat+0x78/0xa0
        do_syscall_64+0x3d/0xb0
        entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> #4 (major_names_lock){+.+.}-{3:3}:
        lock_acquire+0xbe/0x1f0
        __mutex_lock_common+0xb6/0xe10
        mutex_lock_nested+0x17/0x20
        blkdev_show+0x19/0x80
        devinfo_show+0x52/0x60
        seq_read_iter+0x2d5/0x3e0
        proc_reg_read_iter+0x41/0x80
        vfs_read+0x2ac/0x330
        ksys_read+0x6b/0xd0
        do_syscall_64+0x3d/0xb0
        entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> #3 (&p->lock){+.+.}-{3:3}:
        lock_acquire+0xbe/0x1f0
        __mutex_lock_common+0xb6/0xe10
        mutex_lock_nested+0x17/0x20
        seq_read_iter+0x37/0x3e0
        generic_file_splice_read+0xf3/0x170
        splice_direct_to_actor+0x14e/0x350
        do_splice_direct+0x84/0xd0
        do_sendfile+0x263/0x430
        __se_sys_sendfile64+0x96/0xc0
        do_syscall_64+0x3d/0xb0
        entry_SYSCALL_64_after_hwframe+0x44/0xae

 -> #2 (sb_writers#3){.+.+}-{0:0}:
        lock_acquire+0xbe/0x1f0
        lo_write_bvec+0x96/0x280 [loop]
        loop_process_work+0xa68/0xc10 [loop]
        process_one_work+0x293/0x480
        worker_thread+0x23d/0x4b0
        kthread+0x163/0x180
        ret_from_fork+0x1f/0x30

 -> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
        lock_acquire+0xbe/0x1f0
        process_one_work+0x280/0x480
        worker_thread+0x23d/0x4b0
        kthread+0x163/0x180
        ret_from_fork+0x1f/0x30

 -> #0 ((wq_completion)loop0){+.+.}-{0:0}:
        validate_chain+0x1f0d/0x33e0
        __lock_acquire+0x92d/0x1030
        lock_acquire+0xbe/0x1f0
        flush_workqueue+0x8c/0x560
        drain_workqueue+0x80/0x140
        destroy_workqueue+0x47/0x4f0
        __loop_clr_fd+0xb4/0x400 [loop]
        blkdev_put+0x14a/0x1d0
        blkdev_close+0x1c/0x20
        __fput+0xfd/0x220
        task_work_run+0x69/0xc0
        exit_to_user_mode_prepare+0x1ce/0x1f0
        syscall_exit_to_user_mode+0x26/0x60
        do_syscall_64+0x4c/0xb0
        entry_SYSCALL_64_after_hwframe+0x44/0xae

 other info that might help us debug this:

 Chain exists of:
   (wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&lo->lo_mutex);
                                lock(&disk->open_mutex);
                                lock(&lo->lo_mutex);
   lock((wq_completion)loop0);

  *** DEADLOCK ***

 2 locks held by systemd-udevd/7568:
  #0: ffff888012554128 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x4c/0x1d0
  #1: ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]

 stack backtrace:
 CPU: 0 PID: 7568 Comm: systemd-udevd Tainted: G            E     5.14.0+ #757
 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
 Call Trace:
  dump_stack_lvl+0x79/0xbf
  print_circular_bug+0x5d6/0x5e0
  ? stack_trace_save+0x42/0x60
  ? save_trace+0x3d/0x2d0
  check_noncircular+0x10b/0x120
  validate_chain+0x1f0d/0x33e0
  ? __lock_acquire+0x953/0x1030
  ? __lock_acquire+0x953/0x1030
  __lock_acquire+0x92d/0x1030
  ? flush_workqueue+0x70/0x560
  lock_acquire+0xbe/0x1f0
  ? flush_workqueue+0x70/0x560
  flush_workqueue+0x8c/0x560
  ? flush_workqueue+0x70/0x560
  ? sched_clock_cpu+0xe/0x1a0
  ? drain_workqueue+0x41/0x140
  drain_workqueue+0x80/0x140
  destroy_workqueue+0x47/0x4f0
  ? blk_mq_freeze_queue_wait+0xac/0xd0
  __loop_clr_fd+0xb4/0x400 [loop]
  ? __mutex_unlock_slowpath+0x35/0x230
  blkdev_put+0x14a/0x1d0
  blkdev_close+0x1c/0x20
  __fput+0xfd/0x220
  task_work_run+0x69/0xc0
  exit_to_user_mode_prepare+0x1ce/0x1f0
  syscall_exit_to_user_mode+0x26/0x60
  do_syscall_64+0x4c/0xb0
  entry_SYSCALL_64_after_hwframe+0x44/0xae
 RIP: 0033:0x7f0fd4c661f7
 Code: 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 13 fc ff ff
 RSP: 002b:00007ffd1c9e9fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
 RAX: 0000000000000000 RBX: 00007f0fd46be6c8 RCX: 00007f0fd4c661f7
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
 RBP: 0000000000000006 R08: 000055fff1eaf400 R09: 0000000000000000
 R10: 00007f0fd46be6c8 R11: 0000000000000246 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000002f08 R15: 00007ffd1c9ea050

Commit 1c500ad706 ("loop: reduce the loop_ctl_mutex scope") is for
breaking "loop_ctl_mutex => &lo->lo_mutex" dependency chain. But enabling
a different block module results in forming circular locking dependency
due to shared major_names_lock mutex.

The simplest fix is to call probe function without holding
major_names_lock [1], but Christoph Hellwig does not like such idea.
Therefore, instead of holding major_names_lock in blkdev_show(),
introduce a different lock for blkdev_show() in order to break
"sb_writers#$N => &p->lock => major_names_lock" dependency chain.

Link: https://lkml.kernel.org/r/b2af8a5b-3c1b-204e-7f56-bea0b15848d6@i-love.sakura.ne.jp [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/18a02da2-0bf3-550e-b071-2b4ab13c49f0@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-07 08:36:21 -06:00
Christoph Hellwig 9f2869921f block: refine the disk_live check in del_gendisk
hidden gendisks will never be marked live.

Fixes: 40b3a52ffc ("block: add a sanity check for a live disk in del_gendisk")
Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210824144310.1487816-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-24 10:10:08 -06:00
Christoph Hellwig c4b2b7d150 block: remove CONFIG_DEBUG_BLOCK_EXT_DEVT
This might have been a neat debug aid when the extended dev_t was
added, but that time is long gone.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210824075216.1179406-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-24 06:42:40 -06:00
Christoph Hellwig 539711d7d6 block: remove a pointless call to MINOR() in device_add_disk
blk_alloc_ext_minor already returns just a minor number, so no need to
mask the high bits.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210824075216.1179406-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-24 06:42:32 -06:00
Luis Chamberlain 83cbce9574 block: add error handling for device_add_disk / add_disk
Properly unwind on errors in device_add_disk.  This is the initial work
as drivers are not converted yet, which will follow in separate patches.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
[hch: major rebase.  All bugs are probably mine]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:55:45 -06:00
Christoph Hellwig 75f4dca596 block: call blk_register_queue earlier in device_add_disk
Ensure that all the sysfs bits are set up before bdev_add is called,
as that will make the upcomding error handling much easier.  However
this means the call to disk_update_readahead has to be split as that
requires a bdi.  Also remove various sanity checks that don't make
sense now that blk_register_queue only has a single caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210818144542.19305-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:55:45 -06:00
Christoph Hellwig bab53f6b61 block: call blk_integrity_add earlier in device_add_disk
Doing all the sysfs file creation before adding the bdev and thus
allowing it to be opened will simplify the about to be added error
handling.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:55:45 -06:00
Christoph Hellwig 9d5ee6767c block: create the bdi link earlier in device_add_disk
This will simplify error handling going forward.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:55:45 -06:00
Christoph Hellwig 8235b5c1e8 block: call bdev_add later in device_add_disk
Once bdev_add is called userspace can open the block device.  Ensure
that the struct device, which is used for refcounting of the disk
besides various other things, is fully setup at that point.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:55:45 -06:00
Christoph Hellwig 52b85909f8 block: fold register_disk into device_add_disk
There is no real reason these should be separate.  Also simplify the
groups assignment a bit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210818144542.19305-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:55:45 -06:00
Christoph Hellwig 40b3a52ffc block: add a sanity check for a live disk in del_gendisk
Add a sanity check to del_gendisk to do nothing when the disk wasn't
successfully added.  This papers over the complete lack of add_disk
error handling, which is about to get fixed gradually.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210818144542.19305-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:55:45 -06:00
Christoph Hellwig d152c682f0 block: add an explicit ->disk backpointer to the request_queue
Replace the magic lookup through the kobject tree with an explicit
backpointer, given that the device model links are set up and torn
down at times when I/O is still possible, leading to potential
NULL or invalid pointer dereferences.

Fixes: edb0872f44 ("block: move the bdi from the request_queue to the gendisk")
Reported-by: syzbot <syzbot+aa0801b6b32dca9dda82@syzkaller.appspotmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Link: https://lore.kernel.org/r/20210816134624.GA24234@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:54:31 -06:00
Christoph Hellwig 61a35cfc26 block: hold a request_queue reference for the lifetime of struct gendisk
Acquire the queue ref dropped in disk_release in __blk_alloc_disk so any
allocate gendisk always has a queue reference.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816131910.615153-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:54:31 -06:00
Christoph Hellwig 4a1fa41d30 block: pass a request_queue to __blk_alloc_disk
Pass in a request_queue and assign disk->queue in __blk_alloc_disk to
ensure struct gendisk always has a valid ->queue pointer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816131910.615153-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:54:30 -06:00
Christoph Hellwig a58bd7683f block: remove the minors argument to __alloc_disk_node
This was a leftover from the legacy alloc_disk interface.  Switch
the scsi ULPs and dasd to set ->minors directly like all other
drivers and remove the argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>	[dasd]
Link: https://lore.kernel.org/r/20210816131910.615153-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:54:30 -06:00
Christoph Hellwig 4dcc4874de block: cleanup the lockdep handling in *alloc_disk
Pass the lockdep name to the low-level __blk_alloc_disk helper and
hardcode the name for it given that the number of minors or node_id
are not very useful information.  While this passes a pointless
argument for non-lockdep builds that is not really an issue as
disk allocation is a probe time only slow path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816131910.615153-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:54:30 -06:00
Christoph Hellwig 889c05cc58 block: ensure the bdi is freed after inode_detach_wb
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>
2021-08-16 10:49:11 -06:00
Christoph Hellwig 9451aa0aac block: free the extended dev_t minor later
The dev_t is used as the inode hash, so we should only released it
once then block device inode is gone from the inode cache.  Move it
to bdev_free_inode to ensure that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816122614.601358-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-16 10:49:11 -06:00
Christoph Hellwig 50b4aecfbb block: remove GENHD_FL_UP
Just check inode_unhashed on the whole device bdev inode instead,
and provide a helper to check for that information.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210809064028.1198327-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-12 10:29:36 -06:00
Christoph Hellwig edb0872f44 block: move the bdi from the request_queue to the gendisk
The backing device information only makes sense for file system I/O,
and thus belongs into the gendisk and not the lower level request_queue
structure.  Move it there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210809141744.1203023-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09 11:53:23 -06:00
Christoph Hellwig d1254a8749 block: remove support for delayed queue registrations
Now that device mapper has been changed to register the disk once
it is fully ready all this code is unused.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210804094147.459763-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09 11:50:43 -06:00
Christoph Hellwig d626338735 block: support delayed holder registration
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>
2021-08-09 11:50:42 -06:00
Christoph Hellwig 0dbcfe247f block: look up holders by bdev
Invert they way the holder relations are tracked.  This very
slightly reduces the memory overhead for partitioned devices.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210804094147.459763-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09 11:50:42 -06:00
Matteo Croce 13927b31b1 block: export diskseq in sysfs
Add a new sysfs handle to export the new diskseq value.
Place it in <sysfs>/block/<disk>/diskseq and document it.

    $ grep . /sys/class/block/*/diskseq
    /sys/class/block/loop0/diskseq:13
    /sys/class/block/loop1/diskseq:14
    /sys/class/block/loop2/diskseq:5
    /sys/class/block/loop3/diskseq:6
    /sys/class/block/ram0/diskseq:1
    /sys/class/block/ram1/diskseq:2
    /sys/class/block/vda/diskseq:7

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Link: https://lore.kernel.org/r/20210712230530.29323-5-mcroce@linux.microsoft.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Matteo Croce 87eb710747 block: export the diskseq in uevents
Export the newly introduced diskseq in uevents:

    $ udevadm info /sys/class/block/* |grep -e DEVNAME -e DISKSEQ
    E: DEVNAME=/dev/loop0
    E: DISKSEQ=1
    E: DEVNAME=/dev/loop1
    E: DISKSEQ=2
    E: DEVNAME=/dev/loop2
    E: DISKSEQ=3
    E: DEVNAME=/dev/loop3
    E: DISKSEQ=4
    E: DEVNAME=/dev/loop4
    E: DISKSEQ=5
    E: DEVNAME=/dev/loop5
    E: DISKSEQ=6
    E: DEVNAME=/dev/loop6
    E: DISKSEQ=7
    E: DEVNAME=/dev/loop7
    E: DISKSEQ=8
    E: DEVNAME=/dev/nvme0n1
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p1
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p2
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p3
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p4
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p5
    E: DISKSEQ=9
    E: DEVNAME=/dev/sda
    E: DISKSEQ=10
    E: DEVNAME=/dev/sda1
    E: DISKSEQ=10
    E: DEVNAME=/dev/sda2
    E: DISKSEQ=10

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Link: https://lore.kernel.org/r/20210712230530.29323-3-mcroce@linux.microsoft.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Matteo Croce cf17994855 block: add disk sequence number
Associating uevents with block devices in userspace is difficult and racy:
the uevent netlink socket is lossy, and on slow and overloaded systems
has a very high latency.
Block devices do not have exclusive owners in userspace, any process can
set one up (e.g. loop devices). Moreover, device names can be reused
(e.g. loop0 can be reused again and again). A userspace process setting
up a block device and watching for its events cannot thus reliably tell
whether an event relates to the device it just set up or another earlier
instance with the same name.

Being able to set a UUID on a loop device would solve the race conditions.
But it does not allow to derive orderings from uevents: if you see a
uevent with a UUID that does not match the device you are waiting for,
you cannot tell whether it's because the right uevent has not arrived yet,
or it was already sent and you missed it. So you cannot tell whether you
should wait for it or not.

Associating a unique, monotonically increasing sequential number to the
lifetime of each block device, which can be retrieved with an ioctl
immediately upon setting it up, allows to solve the race conditions with
uevents, and also allows userspace processes to know whether they should
wait for the uevent they need or if it was dropped and thus they should
move on.

Additionally, increment the disk sequence number when the media change,
i.e. on DISK_EVENT_MEDIA_CHANGE event.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Link: https://lore.kernel.org/r/20210712230530.29323-2-mcroce@linux.microsoft.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Christoph Hellwig abd2864a3e block: remove disk_name()
Remove the disk_name function now that all users are gone.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210727062518.122108-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Christoph Hellwig a291bb43e5 block: use the %pg format specifier in show_partition
Simplify printing the partition name by using the %pg format specifier
that is equivalent to a bdevname call.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210727062518.122108-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Christoph Hellwig a9e7bc3de4 block: use the %pg format specifier in printk_all_partitions
Simplify printing the partition name by using the %pg format specifier
that is equivalent to a bdevname call.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210727062518.122108-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Abd-Alrhman Masalkhi 26e2d7a362 block: reduce stack usage in diskstats_show
I have compiled the kernel with a cross compiler "hppa-linux-gnu-" v9.3.0
on x86-64 host machine. I got the following warning:

block/genhd.c: In function ‘diskstats_show’:
block/genhd.c:1227:1: warning: the frame size of 1688 bytes is larger
than 1280 bytes [-Wframe-larger-than=]
 1227  |  }

By Reduced the stack footprint by using the %pg printk specifier instead
of disk_name to remove the need for the on-stack buffer.

Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20210727062518.122108-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Christoph Hellwig 2f4731dcd0 block: remove bdput
Now that we've stopped using inode references for anything meaninful
in the block layer get rid of the helper to put it and just open code
the call to iput on the block_device inode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Chaitanya Kulkarni <ckulkarnilinux@gmail.com>
Link: https://lore.kernel.org/r/20210722075402.983367-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Christoph Hellwig d7a66574b3 block: unhash the whole device inode earlier
Unhash the whole device inode early in del_gendisk.  This allows to
remove the first GENHD_FL_UP check in the open path as we simply
won't find a just removed inode.  The second non-racy check after
taking open_mutex is still kept.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210722075402.983367-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-02 13:37:28 -06:00
Christoph Hellwig 340e845738 block: delay freeing the gendisk
blkdev_get_no_open acquires a reference to the block_device through
the block device inode and then tries to acquire a device model
reference to the gendisk.  But at this point the disk migh already
be freed (although the race is free).  Fix this by only freeing the
gendisk from the whole device bdevs ->free_inode callback as well.

Fixes: 22ae8ce8b8 ("block: simplify bdev/disk lookup in blkdev_get")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210722075402.983367-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-27 19:35:47 -06:00
Christoph Hellwig 498dcc13fd block: grab a device refcount in disk_uevent
Sending uevents requires the struct device to be alive.  To
ensure that grab the device refcount instead of just an inode
reference.

Fixes: bc359d03c7 ("block: add a disk_uevent helper")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210701081638.246552-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-01 10:21:24 -06:00
Christoph Hellwig 2bc8cda5ea block: add the events* attributes to disk_attrs
Add the events attributes to the disk_attrs array, which ensures they are
added by the driver core when the device is created rather than adding
them after the device has been added, which is racy versus uevents and
requires more boilerplate code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210624073843.251178-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-24 12:00:22 -06:00
Christoph Hellwig d5870edfa3 block: move the disk events code to a separate file
Move the code for handling disk events from genhd.c into a new file
as it isn't very related to the rest of the file while at the same
time requiring lots of forward declarations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210624073843.251178-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-24 12:00:22 -06:00
Christoph Hellwig 0e0ccdecb3 block: remove bdget_disk
Just opencode the xa_load in the callers, as none of them actually
needs a reference to the bdev.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210525061301.2242282-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-01 07:47:14 -06:00
Christoph Hellwig c97d93c31e block: factor out a part_devt helper
Add a helper to find the dev_t for a disk + partno tuple.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210525061301.2242282-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-01 07:45:49 -06:00
Christoph Hellwig a8698707a1 block: move bd_mutex to struct gendisk
Replace the per-block device bd_mutex with a per-gendisk open_mutex,
thus simplifying locking wherever we deal with partitions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Link: https://lore.kernel.org/r/20210525061301.2242282-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-01 07:44:32 -06:00
Christoph Hellwig f525464a80 block: add blk_alloc_disk and blk_cleanup_disk APIs
Add two new APIs to allocate and free a gendisk including the
request_queue for use with BIO based drivers.  This is to avoid
boilerplate code in drivers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-01 07:42:23 -06:00
Christoph Hellwig 958229a7c5 block: add a flag to make put_disk on partially initalized disks safer
Add a flag to indicate that __device_add_disk did grab a queue reference
so that disk_release only drops it if we actually had it.  This sort
out one of the major pitfals with partially initialized gendisk that
a lot of drivers did get wrong or still do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-01 07:42:23 -06:00
Christoph Hellwig 0d1feb72ff block: automatically enable GENHD_FL_EXT_DEVT
Automatically set the GENHD_FL_EXT_DEVT flag for all disks allocated
without an explicit number of minors.  This is what all new block
drivers should do, so make sure it is the default without boilerplate
code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-01 07:42:23 -06:00
Christoph Hellwig 2e3c73fa0c block: move the DISK_MAX_PARTS sanity check into __device_add_disk
Keep this together with the first place that actually looks at
->minors and prepare for not passing a minors argument to
alloc_disk.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-01 07:42:23 -06:00
Christoph Hellwig 7c3f828b52 block: refactor device number setup in __device_add_disk
Untangle the mess around blk_alloc_devt by moving the check for
the used allocation scheme into the callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210521055116.1053587-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-01 07:42:22 -06:00
Christoph Hellwig 6c60ff048c block: prevent block device lookups at the beginning of del_gendisk
As an artifact of how gendisk lookup used to work in earlier kernels,
GENHD_FL_UP is only cleared very late in del_gendisk, and a global lock
is used to prevent opens from succeeding while del_gendisk is tearing
down the gendisk.  Switch to clearing the flag early and under bd_mutex
so that callers can use bd_mutex to stabilize the flag, which removes
the need for the global mutex.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210514131842.1600568-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-05-20 07:59:35 -06:00
Christoph Hellwig 3212135a71 block: remove disk_part_iter
Just open code the xa_for_each in the remaining user.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-12-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-08 10:24:36 -06:00
Christoph Hellwig 7fae67cc9c block: simplify diskstats_show
Just use xa_for_each to iterate over the partitions as there is no need
to grab a reference to each partition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-11-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-08 10:24:36 -06:00
Christoph Hellwig ecc75a98b8 block: simplify show_partition
Just use xa_for_each to iterate over the partitions as there is no need
to grab a reference to each partition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-08 10:24:36 -06:00
Christoph Hellwig e559f58d20 block: simplify printk_all_partitions
Just use xa_for_each to iterate over the partitions as there is no need
to grab a reference to each partition.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-08 10:24:36 -06:00
Christoph Hellwig c76f48eb5c block: take bd_mutex around delete_partitions in del_gendisk
There is nothing preventing an ioctl from trying do delete partition
concurrenly with del_gendisk, so take open_mutex to serialize against
that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210406062303.811835-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-08 10:24:36 -06:00