linux-toradex.git/drivers/block/xen-blkback, branch v3.16-rc5

xen-blkback: defer freeing blkif to avoid blocking xenwatch

2014-05-28T18:17:32+00:00

Currently xenwatch blocks in VBD disconnect, waiting for all pending I/O
requests to finish. If the VBD is attached to a hot-swappable disk, then
xenwatch can hang for a long period of time, stalling other watches.

 INFO: task xenwatch:39 blocked for more than 120 seconds.
 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 ffff880057f01bd0 0000000000000246 ffff880057f01ac0 ffffffff810b0782
 ffff880057f01ad0 00000000000131c0 0000000000000004 ffff880057edb040
 ffff8800344c6080 0000000000000000 ffff880058c00ba0 ffff880057edb040
 Call Trace:
 [] ? irq_to_desc+0x12/0x20
 [] ? list_del+0x11/0x40
 [] ? wait_for_common+0x60/0x160
 [] ? _raw_spin_lock_irqsave+0x2f/0x50
 [] ? _raw_spin_unlock_irqrestore+0x19/0x20
 [] schedule+0x3a/0x60
 [] xen_blkif_disconnect+0x8a/0x100 [xen_blkback]
 [] ? wake_up_bit+0x40/0x40
 [] xen_blkbk_remove+0xae/0x1e0 [xen_blkback]
 [] xenbus_dev_remove+0x44/0x90
 [] __device_release_driver+0x77/0xd0
 [] device_release_driver+0x28/0x40
 [] bus_remove_device+0x78/0xe0
 [] device_del+0x12f/0x1a0
 [] device_unregister+0x1d/0x60
 [] frontend_changed+0xa6/0x4d0 [xen_blkback]
 [] ? frontend_changed+0x192/0x650 [xen_netback]
 [] ? cmp_dev+0x60/0x60
 [] ? bus_for_each_dev+0x94/0xa0
 [] xenbus_otherend_changed+0xbe/0x120
 [] frontend_changed+0xb/0x10
 [] xenwatch_thread+0xf2/0x130
 [] ? wake_up_bit+0x40/0x40
 [] ? xenbus_directory+0x80/0x80
 [] kthread+0x96/0xa0
 [] kernel_thread_helper+0x4/0x10
 [] ? int_ret_from_sys_call+0x7/0x1b
 [] ? retint_restore_args+0x5/0x6
 [] ? gs_change+0x13/0x13

With this patch, when there is still pending I/O, the actual disconnect
is done by the last reference holder (last pending I/O request). In this
case, xenwatch doesn't block indefinitely.

Signed-off-by: Valentin Priescu 
Reviewed-by: Steven Kady 
Reviewed-by: Steven Noonan 
Reviewed-by: David Vrabel 
Signed-off-by: Konrad Rzeszutek Wilk

xen/blkback: disable discard feature if requested by toolstack

2014-05-28T18:17:28+00:00

Newer toolstacks may provide a boolean property "discard-enable" in the
backend node. Its purpose is to disable discard for file backed storage
to avoid fragmentation. Recognize this setting also for physical
storage.  If that property exists and is false, do not advertise
"feature-discard" to the frontend.

Signed-off-by: Olaf Hering 
Signed-off-by: Konrad Rzeszutek Wilk

xen-blkback: init persistent_purge_work work_struct

2014-02-12T03:34:03+00:00

Initialize persistent_purge_work work_struct on xen_blkif_alloc (and
remove the previous initialization done in purge_persistent_gnt). This
prevents flush_work from complaining even if purge_persistent_gnt has
not been used.

Signed-off-by: Roger Pau Monné 
Reviewed-by: David Vrabel 
Tested-by: Sander Eikelenboom 
Signed-off-by: Jens Axboe

Merge branch 'stable/for-jens-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip into for-linus

2014-02-10T19:52:34+00:00

Konrad writes:

Please git pull the following branch:

 git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git stable/for-jens-3.14

which is based off v3.13-rc6. If you would like me to rebase it on
a different branch/tag I would be more than happy to do so.

The patches are all bug-fixes and hopefully can go in 3.14.

They deal with xen-blkback shutdown and cause memory leaks
as well as shutdown races. They should go to stable tree and if you
are OK with I will ask them to backport those fixes.

There is also a fix to xen-blkfront to deal with unexpected state
transition. And lastly a fix to the header where it was using the
__aligned__ unnecessarily.

xen-blkif: drop struct blkif_request_segment_aligned

2014-02-07T18:03:53+00:00

This was wrongly introduced in commit 402b27f9, the only difference
between blkif_request_segment_aligned and blkif_request_segment is
that the former has a named padding, while both share the same
memory layout.

Also correct a few minor glitches in the description, including for it
to no longer assume PAGE_SIZE == 4096.

Signed-off-by: Roger Pau Monné 
[Description fix by Jan Beulich]
Signed-off-by: Jan Beulich 
Reported-by: Jan Beulich 
Cc: Konrad Rzeszutek Wilk 
Cc: David Vrabel 
Cc: Boris Ostrovsky 
Tested-by: Matt Rushton 
Cc: Matt Wilson 
Signed-off-by: Konrad Rzeszutek Wilk

xen-blkback: fix shutdown race

2014-02-07T17:59:30+00:00

Introduce a new variable to keep track of the number of in-flight
requests. We need to make sure that when xen_blkif_put is called the
request has already been freed and we can safely free xen_blkif, which
was not the case before.

Signed-off-by: Roger Pau Monné 
Cc: Konrad Rzeszutek Wilk 
Cc: David Vrabel 
Reviewed-by: Boris Ostrovsky 
Tested-by: Matt Rushton 
Reviewed-by: Matt Rushton 
Cc: Matt Wilson 
Cc: Ian Campbell 
Signed-off-by: Konrad Rzeszutek Wilk

xen-blkback: fix memory leaks

2014-02-07T17:58:46+00:00

I've at least identified two possible memory leaks in blkback, both
related to the shutdown path of a VBD:

- blkback doesn't wait for any pending purge work to finish before
  cleaning the list of free_pages. The purge work will call
  put_free_pages and thus we might end up with pages being added to
  the free_pages list after we have emptied it. Fix this by making
  sure there's no pending purge work before exiting
  xen_blkif_schedule, and moving the free_page cleanup code to
  xen_blkif_free.
- blkback doesn't wait for pending requests to end before cleaning
  persistent grants and the list of free_pages. Again this can add
  pages to the free_pages list or persistent grants to the
  persistent_gnts red-black tree. Fixed by moving the persistent
  grants and free_pages cleanup code to xen_blkif_free.

Also, add some checks in xen_blkif_free to make sure we are cleaning
everything.

Signed-off-by: Roger Pau Monné 
Cc: Konrad Rzeszutek Wilk 
Reviewed-by: David Vrabel 
Cc: Boris Ostrovsky 
Tested-by: Matt Rushton 
Reviewed-by: Matt Rushton 
Cc: Matt Wilson 
Cc: Ian Campbell 
Signed-off-by: Konrad Rzeszutek Wilk

xen-blkback: fix memory leak when persistent grants are used

2014-02-07T17:58:18+00:00

Currently shrink_free_pagepool() is called before the pages used for
persistent grants are released via free_persistent_gnts(). This
results in a memory leak when a VBD that uses persistent grants is
torn down.

Cc: Konrad Rzeszutek Wilk 
Cc: "Roger Pau Monné" 
Cc: Ian Campbell 
Reviewed-by: David Vrabel 
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xen.org
Cc: Anthony Liguori 
Signed-off-by: Matt Rushton 
Signed-off-by: Matt Wilson 
Signed-off-by: Konrad Rzeszutek Wilk

block: Abstract out bvec iterator

2013-11-24T06:33:47+00:00

Immutable biovecs are going to require an explicit iterator. To
implement immutable bvecs, a later patch is going to add a bi_bvec_done
member to this struct; for now, this patch effectively just renames
things.

Signed-off-by: Kent Overstreet 
Cc: Jens Axboe 
Cc: Geert Uytterhoeven 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: "Ed L. Cashin" 
Cc: Nick Piggin 
Cc: Lars Ellenberg 
Cc: Jiri Kosina 
Cc: Matthew Wilcox 
Cc: Geoff Levand 
Cc: Yehuda Sadeh 
Cc: Sage Weil 
Cc: Alex Elder 
Cc: ceph-devel@vger.kernel.org
Cc: Joshua Morris 
Cc: Philip Kelleher 
Cc: Rusty Russell 
Cc: "Michael S. Tsirkin" 
Cc: Konrad Rzeszutek Wilk 
Cc: Jeremy Fitzhardinge 
Cc: Neil Brown 
Cc: Alasdair Kergon 
Cc: Mike Snitzer 
Cc: dm-devel@redhat.com
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: linux390@de.ibm.com
Cc: Boaz Harrosh 
Cc: Benny Halevy 
Cc: "James E.J. Bottomley" 
Cc: Greg Kroah-Hartman 
Cc: "Nicholas A. Bellinger" 
Cc: Alexander Viro 
Cc: Chris Mason 
Cc: "Theodore Ts'o" 
Cc: Andreas Dilger 
Cc: Jaegeuk Kim 
Cc: Steven Whitehouse 
Cc: Dave Kleikamp 
Cc: Joern Engel 
Cc: Prasad Joshi 
Cc: Trond Myklebust 
Cc: KONISHI Ryusuke 
Cc: Mark Fasheh 
Cc: Joel Becker 
Cc: Ben Myers 
Cc: xfs@oss.sgi.com
Cc: Steven Rostedt 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Len Brown 
Cc: Pavel Machek 
Cc: "Rafael J. Wysocki" 
Cc: Herton Ronaldo Krzesinski 
Cc: Ben Hutchings 
Cc: Andrew Morton 
Cc: Guo Chao 
Cc: Tejun Heo 
Cc: Asai Thambi S P 
Cc: Selvan Mani 
Cc: Sam Bradshaw 
Cc: Wei Yongjun 
Cc: "Roger Pau Monné" 
Cc: Jan Beulich 
Cc: Stefano Stabellini 
Cc: Ian Campbell 
Cc: Sebastian Ott 
Cc: Christian Borntraeger 
Cc: Minchan Kim 
Cc: Jiang Liu 
Cc: Nitin Gupta 
Cc: Jerome Marchand 
Cc: Joe Perches 
Cc: Peng Tao 
Cc: Andy Adamson 
Cc: fanchaoting 
Cc: Jie Liu 
Cc: Sunil Mushran 
Cc: "Martin K. Petersen" 
Cc: Namjae Jeon 
Cc: Pankaj Kumar 
Cc: Dan Magenheimer 
Cc: Mel Gorman 6

xen/blkback: fix reference counting

2013-11-08T16:10:27+00:00

If the permission check fails, we drop a reference to the blkif without
having taken it in the first place. The bug was introduced in commit
604c499cbbcc3d5fe5fb8d53306aa0fae1990109 (xen/blkback: Check device
permissions before allowing OP_DISCARD).

Cc: stable@vger.kernel.org
Cc: Jan Beulich 
Cc: Konrad Rzeszutek Wilk 
Signed-off-by: Vegard Nossum 
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Jens Axboe