linux-toradex.git/drivers/block/nbd.c, branch v3.2.42

nbd: fsync and kill block device on shutdown

2013-03-06T03:24:17+00:00

commit 3a2d63f87989e01437ba994df5f297528c353d7d upstream.

There are two problems with shutdown in the NBD driver.

1: Receiving the NBD_DISCONNECT ioctl does not sync the filesystem.

   This patch adds the sync operation into __nbd_ioctl()'s
   NBD_DISCONNECT handler.  This is useful because BLKFLSBUF is restricted
   to processes that have CAP_SYS_ADMIN, and the NBD client may not
   possess it (fsync of the block device does not sync the filesystem,
   either).

2: Once we clear the socket we have no guarantee that later reads will
   come from the same backing storage.

   The patch adds calls to kill_bdev() in __nbd_ioctl()'s socket
   clearing code so the page cache is cleaned, lest reads that hit on the
   page cache will return stale data from the previously-accessible disk.

Example:

    # qemu-nbd -r -c/dev/nbd0 /dev/sr0
    # file -s /dev/nbd0
    /dev/stdin: # UDF filesystem data (version 1.5) etc.
    # qemu-nbd -d /dev/nbd0
    # qemu-nbd -r -c/dev/nbd0 /dev/sda
    # file -s /dev/nbd0
    /dev/stdin: # UDF filesystem data (version 1.5) etc.

While /dev/sda has:

    # file -s /dev/sda
    /dev/sda: x86 boot sector; etc.

Signed-off-by: Paolo Bonzini 
Acked-by: Paul Clements 
Cc: Alex Bligh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.2:
 - Adjusted context
 - s/\bnbd\b/lo/
 - Incorporate export of kill_bdev() from commit ff01bb483265
   ('fs: move code out of buffer.c')]
Signed-off-by: Ben Hutchings

nbd: clear waiting_queue on shutdown

2012-10-10T02:30:46+00:00

commit fded4e090c60100d709318896c79816d68d5b47d upstream.

Fix a serious but uncommon bug in nbd which occurs when there is heavy
I/O going to the nbd device while, at the same time, a failure (server,
network) or manual disconnect of the nbd connection occurs.

There is a small window between the time that the nbd_thread is stopped
and the socket is shutdown where requests can continue to be queued to
nbd's internal waiting_queue.  When this happens, those requests are
never completed or freed.

The fix is to clear the waiting_queue on shutdown of the nbd device, in
the same way that the nbd request queue (queue_head) is already being
cleared.

Signed-off-by: Paul Clements 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.2: local nbd_device pointers are called 'lo' not 'nbd']
Signed-off-by: Ben Hutchings

nbd-replace-some-printk-with-dev_warn-and-dev_info-checkpatch-fixes

2011-08-19T12:48:28+00:00

ERROR: code indent should use tabs where possible
#30: FILE: drivers/block/nbd.c:578:
+^I        dev_info(disk_to_dev(lo->disk), "NBD_DISCONNECT\n");$

total: 1 errors, 0 warnings, 35 lines checked

NOTE: whitespace errors detected, you may wish to use scripts/cleanpatch or
      scripts/cleanfile

./patches/nbd-replace-some-printk-with-dev_warn-and-dev_info.patch has style problems, please review.

If any of these errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.

Please run checkpatch prior to sending patches

Cc: Paul Clements 
Cc: WANG Cong 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

nbd: replace some printk with dev_warn() and dev_info()

2011-08-19T12:48:28+00:00

Signed-off-by: WANG Cong 
Cc: Paul Clements 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

nbd: lower the loglevel of an error message

2011-08-19T12:48:28+00:00

This is only an error, no need to use KERN_CRIT log level.

Signed-off-by: WANG Cong 
Cc: Paul Clements 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

nbd: replace printk KERN_ERR with dev_err()

2011-08-19T12:48:22+00:00

Signed-off-by: WANG Cong 
Cc: Paul Clements 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

nbd: replace sysfs_create_file() with device_create_file()

2011-08-19T12:48:21+00:00

Signed-off-by: WANG Cong 
Cc: Paul Clements 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

nbd: use task_pid_nr() to get current pid

2011-08-19T12:48:17+00:00

Signed-off-by: WANG Cong 
Cc: Paul Clements 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

nbd: adjust 'max_part' according to part_shift

2011-05-28T12:44:46+00:00

The 'max_part' parameter determines how many partitions are supported
on each nbd device. However the actual number can be changed to the
power of 2 minus 1 form during the module initialization as
alloc_disk() is called with (1 << part_shift) for some reason.

So adjust 'max_part' also at least for consistency with loop and brd.
It is exported via sysfs already, and a user should check this value
after module loading if [s]he wants to use that number correctly
(i.e. fdisk or something).

Signed-off-by: Namhyung Kim 
Cc: Laurent Vivier 
Cc: Paul Clements 
Signed-off-by: Jens Axboe

nbd: limit module parameters to a sane value

2011-05-28T12:44:46+00:00

The 'max_part' parameter controls the number of maximum partition
a nbd device can have. However if a user specifies very large
value it would exceed the limitation of device minor number and
can cause a kernel oops (or, at least, produce invalid device
nodes in some cases).

In addition, specifying large 'nbds_max' value causes same
problem for the same reason.

On my desktop, following command results to the kernel bug:

$ sudo modprobe nbd max_part=100000
 kernel BUG at /media/Linux_Data/project/linux/fs/sysfs/group.c:65!
 invalid opcode: 0000 [#1] SMP
 last sysfs file: /sys/devices/virtual/block/nbd4/range
 CPU 1
 Modules linked in: nbd(+) bridge stp llc kvm_intel kvm asus_atk0110 sg sr_mod cdrom

 Pid: 2522, comm: modprobe Tainted: G        W   2.6.39-leonard+ #159 System manufacturer System Product Name/P5G41TD-M PRO
 RIP: 0010:[]  [] internal_create_group+0x2f/0x166
 RSP: 0018:ffff8801009f1de8  EFLAGS: 00010246
 RAX: 00000000ffffffef RBX: ffff880103920478 RCX: 00000000000a7bd3
 RDX: ffffffff81a2dbe0 RSI: 0000000000000000 RDI: ffff880103920478
 RBP: ffff8801009f1e38 R08: ffff880103920468 R09: ffff880103920478
 R10: ffff8801009f1de8 R11: ffff88011eccbb68 R12: ffffffff81a2dbe0
 R13: ffff880103920468 R14: 0000000000000000 R15: ffff880103920400
 FS:  00007f3c49de9700(0000) GS:ffff88011f800000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
 CR2: 00007f3b7fe7c000 CR3: 00000000cd58d000 CR4: 00000000000406e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 Process modprobe (pid: 2522, threadinfo ffff8801009f0000, task ffff8801009a93a0)
 Stack:
  ffff8801009f1e58 ffffffff812e8f6e ffff8801009f1e58 ffffffff812e7a80
  ffff880000000010 ffff880103920400 ffff8801002fd0c0 ffff880103920468
  0000000000000011 ffff880103920400 ffff8801009f1e48 ffffffff8115ab6a
 Call Trace:
  [] ? device_add+0x4f1/0x5e4
  [] ? dev_set_name+0x41/0x43
  [] sysfs_create_group+0x13/0x15
  [] blk_trace_init_sysfs+0x14/0x16
  [] blk_register_queue+0x4c/0xfd
  [] add_disk+0xe4/0x29c
  [] nbd_init+0x2ab/0x30d [nbd]
  [] ? 0xffffffffa007dfff
  [] do_one_initcall+0x7f/0x13e
  [] sys_init_module+0xa1/0x1e3
  [] system_call_fastpath+0x16/0x1b
 Code: 41 57 41 56 41 55 41 54 53 48 83 ec 28 0f 1f 44 00 00 48 89 fb 41 89 f6 49 89 d4 48 85 ff 74 0b 85 f6 75 0b 48 83
  7f 30 00 75 14 <0f> 0b eb fe b9 ea ff ff ff 48 83 7f 30 00 0f 84 09 01 00 00 49
 RIP  [] internal_create_group+0x2f/0x166
  RSP 
 ---[ end trace 753285ffbf72c57c ]---

Signed-off-by: Namhyung Kim 
Cc: Laurent Vivier 
Cc: Paul Clements 
Cc: stable@kernel.org
Signed-off-by: Jens Axboe