1. 06 2月, 2015 5 次提交
  2. 12 12月, 2014 1 次提交
    • M
      bio: modify __bio_add_page() to accept pages that don't start a new segment · fcbf6a08
      Maurizio Lombardi 提交于
      The original behaviour is to refuse to add a new page if the maximum
      number of segments has been reached, regardless of the fact the page we
      are going to add can be merged into the last segment or not.
      
      Unfortunately, when the system runs under heavy memory fragmentation
      conditions, a driver may try to add multiple pages to the last segment.
      The original code won't accept them and EBUSY will be reported to
      userspace.
      
      This patch modifies the function so it refuses to add a page only in case
      the latter starts a new segment and the maximum number of segments has
      already been reached.
      
      The bug can be easily reproduced with the st driver:
      
      1) set CONFIG_SCSI_MPT2SAS_MAX_SGE or CONFIG_SCSI_MPT3SAS_MAX_SGE  to 16
      2) modprobe st buffer_kbs=1024
      3) #dd if=/dev/zero of=/dev/st0 bs=1M count=10
         dd: error writing `/dev/st0': Device or resource busy
      Signed-off-by: NMaurizio Lombardi <mlombard@redhat.com>
      Signed-off-by: NMing Lei <ming.lei@canonical.com>
      Cc: Jet Chen <jet.chen@intel.com>
      Cc: Tomas Henzl <thenzl@redhat.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      fcbf6a08
  3. 24 11月, 2014 1 次提交
  4. 04 10月, 2014 1 次提交
  5. 02 8月, 2014 1 次提交
    • M
      block: use kmalloc alignment for bio slab · 6a241483
      Mikulas Patocka 提交于
      Various subsystems can ask the bio subsystem to create a bio slab cache
      with some free space before the bio.  This free space can be used for any
      purpose.  Device mapper uses this per-bio-data feature to place some
      target-specific and device-mapper specific data before the bio, so that
      the target-specific data doesn't have to be allocated separately.
      
      This per-bio-data mechanism is used in place of kmalloc, so we need the
      allocated slab to have the same memory alignment as memory allocated
      with kmalloc.
      
      Change bio_find_or_create_slab() so that it uses ARCH_KMALLOC_MINALIGN
      alignment when creating the slab cache.  This is needed so that dm-crypt
      can use per-bio-data for encryption - the crypto subsystem assumes this
      data will have the same alignment as kmalloc'ed memory.
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NMike Snitzer <snitzer@redhat.com>
      Acked-by: NJens Axboe <axboe@fb.com>
      6a241483
  6. 15 7月, 2014 1 次提交
  7. 02 7月, 2014 1 次提交
    • M
      bio: modify __bio_add_page() to accept pages that don't start a new segment · 254c4407
      Maurizio Lombardi 提交于
      The original behaviour is to refuse to add a new page if the maximum
      number of segments has been reached, regardless of the fact the page we
      are going to add can be merged into the last segment or not.
      
      Unfortunately, when the system runs under heavy memory fragmentation
      conditions, a driver may try to add multiple pages to the last segment.
      The original code won't accept them and EBUSY will be reported to
      userspace.
      
      This patch modifies the function so it refuses to add a page only in case
      the latter starts a new segment and the maximum number of segments has
      already been reached.
      
      The bug can be easily reproduced with the st driver:
      
      1) set CONFIG_SCSI_MPT2SAS_MAX_SGE or CONFIG_SCSI_MPT3SAS_MAX_SGE  to 16
      2) modprobe st buffer_kbs=1024
      3) #dd if=/dev/zero of=/dev/st0 bs=1M count=10
         dd: error writing `/dev/st0': Device or resource busy
      
      [ming.lei@canonical.com: update bi_iter.bi_size before recounting segments]
      Signed-off-by: NMaurizio Lombardi <mlombard@redhat.com>
      Signed-off-by: NMing Lei <ming.lei@canonical.com>
      Tested-by: NDongsu Park <dongsu.park@profitbricks.com>
      Tested-by: NJet Chen <jet.chen@intel.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: Kent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      254c4407
  8. 25 6月, 2014 1 次提交
    • J
      block: add support for limiting gaps in SG lists · 66cb45aa
      Jens Axboe 提交于
      Another restriction inherited for NVMe - those devices don't support
      SG lists that have "gaps" in them. Gaps refers to cases where the
      previous SG entry doesn't end on a page boundary. For NVMe, all SG
      entries must start at offset 0 (except the first) and end on a page
      boundary (except the last).
      Signed-off-by: NJens Axboe <axboe@fb.com>
      66cb45aa
  9. 11 6月, 2014 1 次提交
  10. 06 6月, 2014 1 次提交
    • J
      block: add notion of a chunk size for request merging · 762380ad
      Jens Axboe 提交于
      Some drivers have different limits on what size a request should
      optimally be, depending on the offset of the request. Similar to
      dividing a device into chunks. Add a setting that allows the driver
      to inform the block layer of such a chunk size. The block layer will
      then prevent merging across the chunks.
      
      This is needed to optimally support NVMe with a non-zero stripe size.
      Signed-off-by: NJens Axboe <axboe@fb.com>
      762380ad
  11. 19 5月, 2014 1 次提交
  12. 14 5月, 2014 1 次提交
    • T
      cgroup: rename css_tryget*() to css_tryget_online*() · ec903c0c
      Tejun Heo 提交于
      Unlike the more usual refcnting, what css_tryget() provides is the
      distinction between online and offline csses instead of protection
      against upping a refcnt which already reached zero.  cgroup is
      planning to provide actual tryget which fails if the refcnt already
      reached zero.  Let's rename the existing trygets so that they clearly
      indicate that they're onliness.
      
      I thought about keeping the existing names as-are and introducing new
      names for the planned actual tryget; however, given that each
      controller participates in the synchronization of the online state, it
      seems worthwhile to make it explicit that these functions are about
      on/offline state.
      
      Rename css_tryget() to css_tryget_online() and css_tryget_from_dir()
      to css_tryget_online_from_dir().  This is pure rename.
      
      v2: cgroup_freezer grew new usages of css_tryget().  Update
          accordingly.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: NMichal Hocko <mhocko@suse.cz>
      Acked-by: NLi Zefan <lizefan@huawei.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
      ec903c0c
  13. 23 4月, 2014 2 次提交
  14. 22 4月, 2014 1 次提交
  15. 02 4月, 2014 1 次提交
  16. 19 2月, 2014 1 次提交
  17. 11 2月, 2014 1 次提交
  18. 08 2月, 2014 1 次提交
    • T
      cgroup: clean up cgroup_subsys names and initialization · 073219e9
      Tejun Heo 提交于
      cgroup_subsys is a bit messier than it needs to be.
      
      * The name of a subsys can be different from its internal identifier
        defined in cgroup_subsys.h.  Most subsystems use the matching name
        but three - cpu, memory and perf_event - use different ones.
      
      * cgroup_subsys_id enums are postfixed with _subsys_id and each
        cgroup_subsys is postfixed with _subsys.  cgroup.h is widely
        included throughout various subsystems, it doesn't and shouldn't
        have claim on such generic names which don't have any qualifier
        indicating that they belong to cgroup.
      
      * cgroup_subsys->subsys_id should always equal the matching
        cgroup_subsys_id enum; however, we require each controller to
        initialize it and then BUG if they don't match, which is a bit
        silly.
      
      This patch cleans up cgroup_subsys names and initialization by doing
      the followings.
      
      * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each
        cgroup_subsys with _cgrp_subsys.
      
      * With the above, renaming subsys identifiers to match the userland
        visible names doesn't cause any naming conflicts.  All non-matching
        identifiers are renamed to match the official names.
      
        cpu_cgroup -> cpu
        mem_cgroup -> memory
        perf -> perf_event
      
      * controllers no longer need to initialize ->subsys_id and ->name.
        They're generated in cgroup core and set automatically during boot.
      
      * Redundant cgroup_subsys declarations removed.
      
      * While updating BUG_ON()s in cgroup_init_early(), convert them to
        WARN()s.  BUGging that early during boot is stupid - the kernel
        can't print anything, even through serial console and the trap
        handler doesn't even link stack frame properly for back-tracing.
      
      This patch doesn't introduce any behavior changes.
      
      v2: Rebased on top of fe1217c4 ("net: net_cls: move cgroupfs
          classid handling into core").
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Acked-by: NNeil Horman <nhorman@tuxdriver.com>
      Acked-by: N"David S. Miller" <davem@davemloft.net>
      Acked-by: N"Rafael J. Wysocki" <rjw@rjwysocki.net>
      Acked-by: NMichal Hocko <mhocko@suse.cz>
      Acked-by: NPeter Zijlstra <peterz@infradead.org>
      Acked-by: NAristeu Rozanski <aris@redhat.com>
      Acked-by: NIngo Molnar <mingo@redhat.com>
      Acked-by: NLi Zefan <lizefan@huawei.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Serge E. Hallyn <serue@us.ibm.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: Thomas Graf <tgraf@suug.ch>
      073219e9
  19. 09 1月, 2014 2 次提交
  20. 24 11月, 2013 15 次提交
    • K
      block: Kill bio_pair_split() · 4b1faf93
      Kent Overstreet 提交于
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      4b1faf93
    • K
      block: Introduce new bio_split() · 20d0189b
      Kent Overstreet 提交于
      The new bio_split() can split arbitrary bios - it's not restricted to
      single page bios, like the old bio_split() (previously renamed to
      bio_pair_split()). It also has different semantics - it doesn't allocate
      a struct bio_pair, leaving it up to the caller to handle completions.
      
      Then convert the existing bio_pair_split() users to the new bio_split()
      - and also nvme, which was open coding bio splitting.
      
      (We have to take that BUG_ON() out of bio_integrity_trim() because this
      bio_split() needs to use it, and there's no reason it has to be used on
      bios marked as cloned; BIO_CLONED doesn't seem to have clearly
      documented semantics anyways.)
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Martin K. Petersen <martin.petersen@oracle.com>
      Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
      Cc: Keith Busch <keith.busch@intel.com>
      Cc: Vishal Verma <vishal.l.verma@intel.com>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Neil Brown <neilb@suse.de>
      20d0189b
    • K
      block: Rename bio_split() -> bio_pair_split() · ee67891b
      Kent Overstreet 提交于
      This is prep work for introducing a more general bio_split().
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: NeilBrown <neilb@suse.de>
      Cc: Alasdair Kergon <agk@redhat.com>
      Cc: Lars Ellenberg <lars.ellenberg@linbit.com>
      Cc: Peter Osterlund <petero2@telia.com>
      Cc: Sage Weil <sage@inktank.com>
      ee67891b
    • K
      block: Generic bio chaining · 196d38bc
      Kent Overstreet 提交于
      This adds a generic mechanism for chaining bio completions. This is
      going to be used for a bio_split() replacement, and it turns out to be
      very useful in a fair amount of driver code - a fair number of drivers
      were implementing this in their own roundabout ways, often painfully.
      
      Note that this means it's no longer to call bio_endio() more than once
      on the same bio! This can cause problems for drivers that save/restore
      bi_end_io. Arguably they shouldn't be saving/restoring bi_end_io at all
      - in all but the simplest cases they'd be better off just cloning the
      bio, and immutable biovecs is making bio cloning cheaper. But for now,
      we add a bio_endio_nodec() for these cases.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      196d38bc
    • K
      block: Remove bi_idx hacks · e90abc8e
      Kent Overstreet 提交于
      Now that drivers have been converted to the new bvec_iter primitives,
      there's no need to trim the bvec before we submit it; and we can't trim
      it once we start sharing bvecs.
      
      It used to be that passing a partially completed bio (i.e. one with
      nonzero bi_idx) to generic_make_request() was a dangerous thing -
      various drivers would choke on such things. But with immutable biovecs
      and our new bio splitting that shares the biovecs, submitting partially
      completed bios has to work (and should work, now that all the drivers
      have been completed to the new primitives)
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      e90abc8e
    • K
      block: Don't save/copy bvec array anymore · c8db4448
      Kent Overstreet 提交于
      Now that drivers have been converted to the bvec_iter primitives, they
      shouldn't be modifying the biovec anymore and thus saving it is
      unnecessary - code that was previously making a backup of the bvec array
      can now just save bio->bi_iter.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      c8db4448
    • K
      dm: Refactor for new bio cloning/splitting · 1c3b13e6
      Kent Overstreet 提交于
      We need to convert the dm code to the new bvec_iter primitives which
      respect bi_bvec_done; they also allow us to drastically simplify dm's
      bio splitting code.
      
      Also, it's no longer necessary to save/restore the bvec array anymore -
      driver conversions for immutable bvecs are done, so drivers should never
      be modifying it.
      
      Also kill bio_sector_offset(), dm was the only user and it doesn't make
      much sense anymore.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Alasdair Kergon <agk@redhat.com>
      Cc: dm-devel@redhat.com
      Reviewed-by: NMike Snitzer <snitzer@redhat.com>
      1c3b13e6
    • K
      block: Add bio_clone_fast() · 59d276fe
      Kent Overstreet 提交于
      bio_clone() just got more expensive - however, most users of bio_clone()
      don't actually need to modify the biovec. If they aren't modifying the
      biovec, and they can guarantee that the original bio isn't freed before
      the clone (also true in most cases), we can just point the clone at the
      original bio's biovec.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      59d276fe
    • K
      block: Refactor bio_clone_bioset() for immutable biovecs · bdb53207
      Kent Overstreet 提交于
      bio_clone() needs to produce a bio that's suitable for the caller to
      munge with the biovec. Part of the immutable biovec patch series is
      fixing stuff up so that submitting partially completed bios is safe and
      works: thus, we now need bio_clone() on a partially completed bio to
      produce a bio for which bi_idx and bi_bvec done are 0 - like they would
      be if the caller had just allocated a new bio.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      bdb53207
    • K
      block: Convert drivers to immutable biovecs · 003b5c57
      Kent Overstreet 提交于
      Now that we've got a mechanism for immutable biovecs -
      bi_iter.bi_bvec_done - we need to convert drivers to use primitives that
      respect it instead of using the bvec array directly.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: NeilBrown <neilb@suse.de>
      Cc: Alasdair Kergon <agk@redhat.com>
      Cc: dm-devel@redhat.com
      003b5c57
    • K
      block: Kill bio_segments()/bi_vcnt usage · 458b76ed
      Kent Overstreet 提交于
      When we start sharing biovecs, keeping bi_vcnt accurate for splits is
      going to be error prone - and unnecessary, if we refactor some code.
      
      So bio_segments() has to go - but most of the existing users just needed
      to know if the bio had multiple segments, which is easier - add a
      bio_multiple_segments() for them.
      
      (Two of the current uses of bio_segments() are going to go away in a
      couple patches, but the current implementation of bio_segments() is
      unsafe as soon as we start doing driver conversions for immutable
      biovecs - so implement a dumb version for bisectability, it'll go away
      in a couple patches)
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Neil Brown <neilb@suse.de>
      Cc: Nagalakshmi Nandigama <Nagalakshmi.Nandigama@lsi.com>
      Cc: Sreekanth Reddy <Sreekanth.Reddy@lsi.com>
      Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
      458b76ed
    • K
      block: Convert bio_copy_data() to bvec_iter · 1cb9dda4
      Kent Overstreet 提交于
      Our fancy new bvec iterator makes code like this much easier to write.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      1cb9dda4
    • K
      block: Immutable bio vecs · 4550dd6c
      Kent Overstreet 提交于
      This adds a mechanism by which we can advance a bio by an arbitrary
      number of bytes without modifying the biovec: bio->bi_iter.bi_bvec_done
      indicates the number of bytes completed in the current bvec.
      
      Various driver code still needs to be updated to not refer to the bvec
      directly before we can use this for interesting things, like efficient
      bio splitting.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
      Cc: Paul Clements <Paul.Clements@steeleye.com>
      Cc: drbd-user@lists.linbit.com
      Cc: nbd-general@lists.sourceforge.net
      4550dd6c
    • K
      block: Convert bio_for_each_segment() to bvec_iter · 7988613b
      Kent Overstreet 提交于
      More prep work for immutable biovecs - with immutable bvecs drivers
      won't be able to use the biovec directly, they'll need to use helpers
      that take into account bio->bi_iter.bi_bvec_done.
      
      This updates callers for the new usage without changing the
      implementation yet.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Geert Uytterhoeven <geert@linux-m68k.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: "Ed L. Cashin" <ecashin@coraid.com>
      Cc: Nick Piggin <npiggin@kernel.dk>
      Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Paul Clements <Paul.Clements@steeleye.com>
      Cc: Jim Paris <jim@jtan.com>
      Cc: Geoff Levand <geoff@infradead.org>
      Cc: Yehuda Sadeh <yehuda@inktank.com>
      Cc: Sage Weil <sage@inktank.com>
      Cc: Alex Elder <elder@inktank.com>
      Cc: ceph-devel@vger.kernel.org
      Cc: Joshua Morris <josh.h.morris@us.ibm.com>
      Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Cc: Jeremy Fitzhardinge <jeremy@goop.org>
      Cc: Neil Brown <neilb@suse.de>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: linux390@de.ibm.com
      Cc: Nagalakshmi Nandigama <Nagalakshmi.Nandigama@lsi.com>
      Cc: Sreekanth Reddy <Sreekanth.Reddy@lsi.com>
      Cc: support@lsi.com
      Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      Cc: Steven Whitehouse <swhiteho@redhat.com>
      Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Guo Chao <yan@linux.vnet.ibm.com>
      Cc: Asai Thambi S P <asamymuthupa@micron.com>
      Cc: Selvan Mani <smani@micron.com>
      Cc: Sam Bradshaw <sbradshaw@micron.com>
      Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
      Cc: Keith Busch <keith.busch@intel.com>
      Cc: Stephen Hemminger <shemminger@vyatta.com>
      Cc: Quoc-Son Anh <quoc-sonx.anh@intel.com>
      Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Jerome Marchand <jmarchan@redhat.com>
      Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
      Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
      Cc: Mike Snitzer <snitzer@redhat.com>
      Cc: Vivek Goyal <vgoyal@redhat.com>
      Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Jan Kara <jack@suse.cz>
      Cc: linux-m68k@lists.linux-m68k.org
      Cc: linuxppc-dev@lists.ozlabs.org
      Cc: drbd-user@lists.linbit.com
      Cc: nbd-general@lists.sourceforge.net
      Cc: cbe-oss-dev@lists.ozlabs.org
      Cc: xen-devel@lists.xensource.com
      Cc: virtualization@lists.linux-foundation.org
      Cc: linux-raid@vger.kernel.org
      Cc: linux-s390@vger.kernel.org
      Cc: DL-MPTFusionLinux@lsi.com
      Cc: linux-scsi@vger.kernel.org
      Cc: devel@driverdev.osuosl.org
      Cc: linux-fsdevel@vger.kernel.org
      Cc: cluster-devel@redhat.com
      Cc: linux-mm@kvack.org
      Acked-by: NGeoff Levand <geoff@infradead.org>
      7988613b
    • K
      block: Convert bio_iovec() to bvec_iter · a4ad39b1
      Kent Overstreet 提交于
      For immutable biovecs, we'll be introducing a new bio_iovec() that uses
      our new bvec iterator to construct a biovec, taking into account
      bvec_iter->bi_bvec_done - this patch updates existing users for the new
      usage.
      
      Some of the existing users really do need a pointer into the bvec array
      - those uses are all going to be removed, but we'll need the
      functionality from immutable to remove them - so for now rename the
      existing bio_iovec() -> __bio_iovec(), and it'll be removed in a couple
      patches.
      Signed-off-by: NKent Overstreet <kmo@daterainc.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: "Ed L. Cashin" <ecashin@coraid.com>
      Cc: Alasdair Kergon <agk@redhat.com>
      Cc: dm-devel@redhat.com
      Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
      a4ad39b1