1. 10 Oct, 2008 2 commits
  2. 21 Jul, 2008 1 commit
  3. 30 Apr, 2008 1 commit
  4. 25 Apr, 2008 3 commits
  5. 08 Feb, 2008 1 commit
  6. 20 Dec, 2007 1 commit
  7. 02 Nov, 2007 1 commit
  8. 20 Oct, 2007 2 commits
  9. 08 Dec, 2006 3 commits
    • Kiyoshi Ueda's avatar
      [PATCH] dm: suspend: add noflush pushback · 2e93ccc1
      Kiyoshi Ueda authored
      
      
      In device-mapper I/O is sometimes queued within targets for later processing.
      For example the multipath target can be configured to store I/O when no paths
      are available instead of returning it -EIO.
      
      This patch allows the device-mapper core to instruct a target to transfer the
      contents of any such in-target queue back into the core.  This frees up the
      resources used by the target so the core can replace that target with an
      alternative one and then resend the I/O to it.  Without this patch the only
      way to change the target in such circumstances involves returning the I/O with
      an error back to the filesystem/application.  In the multipath case, this
      patch will let us add new paths for existing I/O to try after all the existing
      paths have failed.
      
          DMF_NOFLUSH_SUSPENDING
          ----------------------
      
      If the DM_NOFLUSH_FLAG ioctl option is specified at suspend time, the
      DMF_NOFLUSH_SUSPENDING flag is set in md->flags during dm_suspend().  It
      is always cleared before dm_suspend() returns.
      
      The flag must be visible while the target is flushing pending I/Os so it
      is set before presuspend where the flush starts and unset after the wait
      for md->pending where the flush ends.
      
      Target drivers can check this flag by calling dm_noflush_suspending().
      
          DM_MAPIO_REQUEUE / DM_ENDIO_REQUEUE
          -----------------------------------
      
      A target's map() function can now return DM_MAPIO_REQUEUE to request the
      device mapper core queue the bio.
      
      Similarly, a target's end_io() function can return DM_ENDIO_REQUEUE to request
      the same.  This has been labelled 'pushback'.
      
      The __map_bio() and clone_endio() functions in the core treat these return
      values as errors and call dec_pending() to end the I/O.
      
          dec_pending
          -----------
      
      dec_pending() saves the pushback request in struct dm_io->error.  Once all
      the split clones have ended, dec_pending() will put the original bio on
      the md->pushback list.  Note that this supercedes any I/O errors.
      
      It is possible for the suspend with DM_NOFLUSH_FLAG to be aborted while
      in progress (e.g. by user interrupt).  dec_pending() checks for this and
      returns -EIO if it happened.
      
          pushdback list and pushback_lock
          --------------------------------
      
      The bio is queued on md->pushback temporarily in dec_pending(), and after
      all pending I/Os return, md->pushback is merged into md->deferred in
      dm_suspend() for re-issuing at resume time.
      
      md->pushback_lock protects md->pushback.
      The lock should be held with irq disabled because dec_pending() can be
      called from interrupt context.
      
      Queueing bios to md->pushback in dec_pending() must be done atomically
      with the check for DMF_NOFLUSH_SUSPENDING flag.  So md->pushback_lock is
      held when checking the flag.  Otherwise dec_pending() may queue a bio to
      md->pushback after the interrupted dm_suspend() flushes md->pushback.
      Then the bio would be left in md->pushback.
      
      Flag setting in dm_suspend() can be done without md->pushback_lock because
      the flag is checked only after presuspend and the set value is already
      made visible via the target's presuspend function.
      
      The flag can be checked without md->pushback_lock (e.g. the first part of
      the dec_pending() or target drivers), because the flag is checked again
      with md->pushback_lock held when the bio is really queued to md->pushback
      as described above.  So even if the flag is cleared after the lockless
      checkings, the bio isn't left in md->pushback but returned to applications
      with -EIO.
      
          Other notes on the current patch
          --------------------------------
      
      - md->pushback is added to the struct mapped_device instead of using
        md->deferred directly because md->io_lock which protects md->deferred is
        rw_semaphore and can't be used in interrupt context like dec_pending(),
        and md->io_lock protects the DMF_BLOCK_IO flag of md->flags too.
      
      - Don't issue lock_fs() in dm_suspend() if the DM_NOFLUSH_FLAG
        ioctl option is specified, because I/Os generated by lock_fs() would be
        pushed back and never return if there were no valid devices.
      
      - If an error occurs in dm_suspend() after the DMF_NOFLUSH_SUSPENDING
        flag is set, md->pushback must be flushed because I/Os may be queued to
        the list already.  (flush_and_out label in dm_suspend())
      
          Test results
          ------------
      
      I have tested using multipath target with the next patch.
      
      The following tests are for regression/compatibility:
        - I/Os succeed when valid paths exist;
        - I/Os fail when there are no valid paths and queue_if_no_path is not
          set;
        - I/Os are queued in the multipath target when there are no valid paths and
          queue_if_no_path is set;
        - The queued I/Os above fail when suspend is issued without the
          DM_NOFLUSH_FLAG ioctl option.  I/Os spanning 2 multipath targets also
          fail.
      
      The following tests are for the normal code path of new pushback feature:
        - Queued I/Os in the multipath target are flushed from the target
          but don't return when suspend is issued with the DM_NOFLUSH_FLAG
          ioctl option;
        - The I/Os above are queued in the multipath target again when
          resume is issued without path recovery;
        - The I/Os above succeed when resume is issued after path recovery
          or table load;
        - Queued I/Os in the multipath target succeed when resume is issued
          with the DM_NOFLUSH_FLAG ioctl option after table load. I/Os
          spanning 2 multipath targets also succeed.
      
      The following tests are for the error paths of the new pushback feature:
        - When the bdget_disk() fails in dm_suspend(), the
          DMF_NOFLUSH_SUSPENDING flag is cleared and I/Os already queued to the
          pushback list are flushed properly.
        - When suspend with the DM_NOFLUSH_FLAG ioctl option is interrupted,
            o I/Os which had already been queued to the pushback list
              at the time don't return, and are re-issued at resume time;
            o I/Os which hadn't been returned at the time return with EIO.
      Signed-off-by: default avatarKiyoshi Ueda <k-ueda@ct.jp.nec.com>
      Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
      Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
      Cc: dm-devel@redhat.com
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      2e93ccc1
    • Kiyoshi Ueda's avatar
      [PATCH] dm: map and endio return code clarification · 45cbcd79
      Kiyoshi Ueda authored
      
      
      Tighten the use of return values from the target map and end_io functions.
      Values of 2 and above are now explictly reserved for future use.  There are no
      existing targets using such values.
      
      The patch has no effect on existing behaviour.
      
      o Reserve return values of 2 and above from target map functions.
        Any positive value currently indicates "mapping complete", but all
        existing drivers use the value 1.  We now make that a requirement
        so we can assign new meaning to higher values in future.
      
        The new definition of return values from target map functions is:
            < 0 : error
            = 0 : The target will handle the io (DM_MAPIO_SUBMITTED).
            = 1 : Mapping completed (DM_MAPIO_REMAPPED).
            > 1 : Reserved (undefined).  Previously this was the same as '= 1'.
      
      o Reserve return values of 2 and above from target end_io functions
        for similar reasons.
        DM_ENDIO_INCOMPLETE is introduced for a return value of 1.
      
      Test results:
      
        I have tested by using the multipath target.
      
        I/Os succeed when valid paths exist.
      
        I/Os are queued in the multipath target when there are no valid paths and
      queue_if_no_path is set.
      
        I/Os fail when there are no valid paths and queue_if_no_path is not set.
      Signed-off-by: default avatarKiyoshi Ueda <k-ueda@ct.jp.nec.com>
      Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
      Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
      Cc: dm-devel@redhat.com
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      45cbcd79
    • Kiyoshi Ueda's avatar
      [PATCH] dm: suspend: parameter change · a3d77d35
      Kiyoshi Ueda authored
      
      
      Change the interface of dm_suspend() so that we can pass several options
      without increasing the number of parameters.  The existing 'do_lockfs' integer
      parameter is replaced by a flag DM_SUSPEND_LOCKFS_FLAG.
      
      There is no functional change to the code.
      
      Test results:
      I have tested 'dmsetup suspend' command with/without the '--nolockfs'
      option and confirmed the do_lockfs value is correctly set.
      Signed-off-by: default avatarKiyoshi Ueda <k-ueda@ct.jp.nec.com>
      Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
      Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
      Cc: dm-devel@redhat.com
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      a3d77d35
  10. 03 Oct, 2006 4 commits
  11. 26 Jun, 2006 3 commits
  12. 27 Mar, 2006 1 commit
  13. 01 Feb, 2006 1 commit
  14. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4