linux-stable.git/block, branch linux-4.5.y

block: partition: initialize percpuref before sending out KOBJ_ADD

2016-05-04T21:48:57+00:00

commit b30a337ca27c4f40439e4bfb290cba5f88d73bb7 upstream.

The initialization of partition's percpu_ref should have been done before
sending out KOBJ_ADD uevent, which may cause userspace to read partition
table. So the uninitialized percpu_ref may be accessed in data path.

This patch fixes this issue reported by Naveen.

Reported-by: Naveen Kaje 
Tested-by: Naveen Kaje 
Fixes: 6c71013ecb7e2(block: partition: convert percpu ref)
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

dm: fix excessive dm-mq context switching

2016-04-12T14:33:19+00:00

commit 6acfe68bac7e6f16dc312157b1fa6e2368985013 upstream.

Request-based DM's blk-mq support (dm-mq) was reported to be 50% slower
than if an underlying null_blk device were used directly.  One of the
reasons for this drop in performance is that blk_insert_clone_request()
was calling blk_mq_insert_request() with @async=true.  This forced the
use of kblockd_schedule_delayed_work_on() to run the blk-mq hw queues
which ushered in ping-ponging between process context (fio in this case)
and kblockd's kworker to submit the cloned request.  The ftrace
function_graph tracer showed:

  kworker-2013  =>   fio-12190
  fio-12190    =>  kworker-2013
  ...
  kworker-2013  =>   fio-12190
  fio-12190    =>  kworker-2013
  ...

Fixing blk_insert_clone_request()'s blk_mq_insert_request() call to
_not_ use kblockd to submit the cloned requests isn't enough to
eliminate the observed context switches.

In addition to this dm-mq specific blk-core fix, there are 2 DM core
fixes to dm-mq that (when paired with the blk-core fix) completely
eliminate the observed context switching:

1)  don't blk_mq_run_hw_queues in blk-mq request completion

    Motivated by desire to reduce overhead of dm-mq, punting to kblockd
    just increases context switches.

    In my testing against a really fast null_blk device there was no benefit
    to running blk_mq_run_hw_queues() on completion (and no other blk-mq
    driver does this).  So hopefully this change doesn't induce the need for
    yet another revert like commit 621739b00e16ca2d !

2)  use blk_mq_complete_request() in dm_complete_request()

    blk_complete_request() doesn't offer the traditional q->mq_ops vs
    .request_fn branching pattern that other historic block interfaces
    do (e.g. blk_get_request).  Using blk_mq_complete_request() for
    blk-mq requests is important for performance.  It should be noted
    that, like blk_complete_request(), blk_mq_complete_request() doesn't
    natively handle partial completions -- but the request-based
    DM-multipath target does provide the required partial completion
    support by dm.c:end_clone_bio() triggering requeueing of the request
    via dm-mpath.c:multipath_end_io()'s return of DM_ENDIO_REQUEUE.

dm-mq fix #2 is _much_ more important than #1 for eliminating the
context switches.
Before: cpu          : usr=15.10%, sys=59.39%, ctx=7905181, majf=0, minf=475
After:  cpu          : usr=20.60%, sys=79.35%, ctx=2008, majf=0, minf=472

With these changes multithreaded async read IOPs improved from ~950K
to ~1350K for this dm-mq stacked on null_blk test-case.  The raw read
IOPs of the underlying null_blk device for the same workload is ~1950K.

Fixes: 7fb4898e0 ("block: add blk-mq support to blk_insert_cloned_request()")
Fixes: bfebd1cdb ("dm: add full blk-mq support to request-based DM")
Reported-by: Sagi Grimberg 
Signed-off-by: Mike Snitzer 
Acked-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: support large requests in blk_rq_map_user_iov

2016-03-03T21:45:02+00:00

This patch adds support for larger requests in blk_rq_map_user_iov by
allowing it to build multiple bios for a request.  This functionality
used to exist for the non-vectored blk_rq_map_user in the past, and
this patch reuses the existing functionality for it on the unmap side,
which stuck around.  Thanks to the iov_iter API supporting multiple
bios is fairly trivial, as we can just iterate the iov until we've
consumed the whole iov_iter.

Signed-off-by: Christoph Hellwig 
Reported-by: Jeff Lien 
Tested-by: Jeff Lien 
Reviewed-by: Keith Busch 
Signed-off-by: Jens Axboe

block: merge: get the 1st and last bvec via helpers

2016-03-03T21:42:49+00:00

This patch applies the two introduced helpers to
figure out the 1st and last bvec.

Reviewed-by: Sagi Grimberg 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

block: disable block device DAX by default

2016-02-27T18:28:52+00:00

The recent *sync enabling discovered that we are inserting into the
block_device pagecache counter to the expectations of the dirty data
tracking for dax mappings.  This can lead to data corruption.

We want to support DAX for block devices eventually, but it requires
wider changes to properly manage the pagecache.

   dump_stack+0x85/0xc2
   dax_writeback_mapping_range+0x60/0xe0
   blkdev_writepages+0x3f/0x50
   do_writepages+0x21/0x30
   __filemap_fdatawrite_range+0xc6/0x100
   filemap_write_and_wait+0x4a/0xa0
   set_blocksize+0x70/0xd0
   sb_set_blocksize+0x1d/0x50
   ext4_fill_super+0x75b/0x3360
   mount_bdev+0x180/0x1b0
   ext4_mount+0x15/0x20
   mount_fs+0x38/0x170

Mark the support broken so its disabled by default, but otherwise still
available for testing.

Signed-off-by: Dan Williams 
Signed-off-by: Ross Zwisler 
Reported-by: Ross Zwisler 
Suggested-by: Dave Chinner 
Reviewed-by: Jan Kara 
Cc: Jens Axboe 
Cc: Matthew Wilcox 
Cc: Al Viro 
Cc: Theodore Ts'o 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.dk/linux-block

2016-02-17T19:59:23+00:00

Pull block fixes from Jens Axboe:
 "A collection of fixes from the past few weeks that should go into 4.5.
  This contains:

   - Overflow fix for sysfs discard show function from Alan.

   - A stacking limit init fix for max_dev_sectors, so we don't end up
     artificially capping some use cases.  From Keith.

   - Have blk-mq proper end unstarted requests on a dying queue, instead
     of pushing that to the driver.  From Keith.

   - NVMe:
        - Update to Kconfig description for NVME_SCSI, since it was
          vague and having it on is important for some SUSE distros.
          From Christoph.
        - Set of fixes from Keith, around surprise removal. Also kills
          the no-merge flag, so it supports merging.

   - Set of fixes for lightnvm from Matias, Javier, and Wenwei.

   - Fix null_blk oops when asked for lightnvm, but not available.  From
     Matias.

   - Copy-to-user EINTR fix from Hannes, fixing a case where SG_IO fails
     if interrupted by a signal.

   - Two floppy fixes from Jiri, fixing signal handling and blocking
     open.

   - A use-after-free fix for O_DIRECT, from Mike Krinkin.

   - A block module ref count fix from Roman Pen.

   - An fs IO wait accounting fix for O_DSYNC from Stephane Gasparini.

   - Smaller reallo fix for xen-blkfront from Bob Liu.

   - Removal of an unused struct member in the deadline IO scheduler,
     from Tahsin.

   - Also from Tahsin, properly initialize inode struct members
     associated with cgroup writeback, if enabled.

   - From Tejun, ensure that we keep the superblock pinned during cgroup
     writeback"

* 'for-linus' of git://git.kernel.dk/linux-block: (25 commits)
  blk: fix overflow in queue_discard_max_hw_show
  writeback: initialize inode members that track writeback history
  writeback: keep superblock pinned during cgroup writeback association switches
  bio: return EINTR if copying to user space got interrupted
  NVMe: Rate limit nvme IO warnings
  NVMe: Poll device while still active during remove
  NVMe: Requeue requests on suspended queues
  NVMe: Allow request merges
  NVMe: Fix io incapable return values
  blk-mq: End unstarted requests on dying queue
  block: Initialize max_dev_sectors to 0
  null_blk: oops when initializing without lightnvm
  block: fix module reference leak on put_disk() call for cgroups throttle
  nvme: fix Kconfig description for BLK_DEV_NVME_SCSI
  kernel/fs: fix I/O wait not accounted for RW O_DSYNC
  floppy: refactor open() flags handling
  lightnvm: allow to force mm initialization
  lightnvm: check overflow and correct mlc pairs
  lightnvm: fix request intersection locking in rrpc
  lightnvm: warn if irqs are disabled in lock laddr
  ...

blk: fix overflow in queue_discard_max_hw_show

2016-02-17T17:20:42+00:00

We get this right for queue_discard_max_show but not max_hw_show. Follow the
same pattern as queue_discard_max_show instead so that we don't truncate.

Signed-off-by: Alan Cox 
Signed-off-by: Jens Axboe

Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

2016-02-12T17:32:37+00:00

Pull SCSI fixes from James Bottomley:
 "A set of seven fixes:

  Two regressions in the new hisi_sas arm driver, a blacklist entry for
  the marvell console which was causing a reset cascade without it, a
  race fix in the WRITE_SAME/DISCARD routines, a retry fix for the rdac
  driver, without which, it would prematurely return EIO and a couple of
  fixes for the hyper-v storvsc driver"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  block/sd: Return -EREMOTEIO when WRITE SAME and DISCARD are disabled
  SCSI: Add Marvell Console to VPD blacklist
  scsi_dh_rdac: always retry MODE SELECT on command lock violation
  storvsc: Use the specified target ID in device lookup
  storvsc: Install the storvsc specific timeout handler for FC devices
  hisi_sas: fix v1 hw check for slot error
  hisi_sas: add dependency for HAS_IOMEM

bio: return EINTR if copying to user space got interrupted

2016-02-12T15:17:41+00:00

Commit 35dc248383bbab0a7203fca4d722875bc81ef091 introduced a check for
current->mm to see if we have a user space context and only copies data
if we do. Now if an IO gets interrupted by a signal data isn't copied
into user space any more (as we don't have a user space context) but
user space isn't notified about it.

This patch modifies the behaviour to return -EINTR from bio_uncopy_user()
to notify userland that a signal has interrupted the syscall, otherwise
it could lead to a situation where the caller may get a buffer with
no data returned.

This can be reproduced by issuing SG_IO ioctl()s in one thread while
constantly sending signals to it.

Fixes: 35dc248 [SCSI] sg: Fix user memory corruption when SG_IO is interrupted by a signal
Signed-off-by: Johannes Thumshirn 
Signed-off-by: Hannes Reinecke 
Cc: stable@vger.kernel.org # v.3.11+
Signed-off-by: Jens Axboe

blk-mq: End unstarted requests on dying queue

2016-02-11T20:14:00+00:00

Go directly to ending a request if it wasn't started. Previously, completing a
request may invoke a driver callback for a request it didn't initialize.

Signed-off-by: Keith Busch 
Reviewed-by: Sagi Grimberg 
Reviewed-by: Johannes Thumshirn 
Acked-by: Christoph Hellwig 
Signed-off-by: Jens Axboe