1. 22 6月, 2009 4 次提交
    • M
      dm: always hold bdev reference · 32a926da
      Mikulas Patocka 提交于
      Fix a potential deadlock when creating multiple snapshots by holding a
      reference to struct block_device for the whole lifecycle of every dm
      device instead of obtaining it independently at each point it is needed.
      
      bdget_disk() was called while the device was being suspended, in
      dm_suspend().  However there could be other devices already suspended,
      for example when creating additional snapshots of a device. bdget_disk()
      can wait for IO and allocate memory resulting in waiting for the
      already-suspended device - deadlock.
      
      This patch changes the code so that it gets the reference to struct
      block_device when struct mapped_device is allocated and initialized in
      alloc_dev() where it is always OK to allocate memory or wait for I/O.
      It drops the reference when it is destroyed in free_dev().  Thus there
      is no call to bdget_disk() while any device is suspended.
      
      Previously unlock_fs() was called only if bdev was held.  Now it is
      called unconditionally, but the superfluous calls are harmless because
      it returns immediately if the filesystem was not previously frozen.
      
      This patch also now allows the device size to be changed in a
      noflush suspend because the bdev is held.  This has no adverse effect.
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      32a926da
    • M
      dm: rename suspended_bdev to bdev · db8fef4f
      Mikulas Patocka 提交于
      Rename suspended_bdev to bdev.
      
      This patch doesn't change any functionality, just renames the variable.
      In the next patch, the variable will be used even for non-suspended device.
      
      (Pre-requisite for the per-target barrier support patches.)
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      db8fef4f
    • M
      dm: avoid unsupported spanning of md stripe boundaries · 8cbeb67a
      Mikulas Patocka 提交于
      A bio that has two or more vector entries, size less than or equal to
      page size, that crosses a stripe boundary of an underlying md device is
      accepted by device mapper (it conforms to all its limits) but not by the
      underlying device.
      
      The fix is: If device mapper selects the one-page maximum request size,
      it also needs to set its own q->merge_bvec_fn to reject any bios with
      multiple vector entries that span more pages.
      
      The problem was discovered in the following scenario:
        * MD - RAID-0
        * LV on the top of it (raid1, snapshot or striped with chunk
      size/stripe larger than RAID-0 stripe)
        * one of the logical volumes is exported to xen domU
        * inside xen domU it is partitioned, the key point is that the partition
      must be unaligned on page boundary (fdisk normally aligns the partition to
      63 sectors which will trigger it)
        * install the system on the partitioned disk in domU
      This causes I/O failures in dom0.
      Reference: https://bugzilla.redhat.com/show_bug.cgi?id=223947Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      8cbeb67a
    • M
      dm: sysfs skip output when device is being destroyed · 4d89b7b4
      Milan Broz 提交于
      Do not process sysfs attributes when device is being destroyed.
      
      Otherwise code can cause
        BUG_ON(test_bit(DMF_FREEING, &md->flags));
      in dm_put() call.
      
      Cc: stable@kernel.org
      Signed-off-by: NMilan Broz <mbroz@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      4d89b7b4
  2. 16 6月, 2009 1 次提交
  3. 10 6月, 2009 1 次提交
    • L
      tracing/events: convert block trace points to TRACE_EVENT() · 55782138
      Li Zefan 提交于
      TRACE_EVENT is a more generic way to define tracepoints. Doing so adds
      these new capabilities to this tracepoint:
      
        - zero-copy and per-cpu splice() tracing
        - binary tracing without printf overhead
        - structured logging records exposed under /debug/tracing/events
        - trace events embedded in function tracer output and other plugins
        - user-defined, per tracepoint filter expressions
        ...
      
      Cons:
      
        - no dev_t info for the output of plug, unplug_timer and unplug_io events.
          no dev_t info for getrq and sleeprq events if bio == NULL.
          no dev_t info for rq_abort,...,rq_requeue events if rq->rq_disk == NULL.
      
          This is mainly because we can't get the deivce from a request queue.
          But this may change in the future.
      
        - A packet command is converted to a string in TP_assign, not TP_print.
          While blktrace do the convertion just before output.
      
          Since pc requests should be rather rare, this is not a big issue.
      
        - In blktrace, an event can have 2 different print formats, but a TRACE_EVENT
          has a unique format, which means we have some unused data in a trace entry.
      
          The overhead is minimized by using __dynamic_array() instead of __array().
      
      I've benchmarked the ioctl blktrace vs the splice based TRACE_EVENT tracing:
      
            dd                   dd + ioctl blktrace       dd + TRACE_EVENT (splice)
      1     7.36s, 42.7 MB/s     7.50s, 42.0 MB/s          7.41s, 42.5 MB/s
      2     7.43s, 42.3 MB/s     7.48s, 42.1 MB/s          7.43s, 42.4 MB/s
      3     7.38s, 42.6 MB/s     7.45s, 42.2 MB/s          7.41s, 42.5 MB/s
      
      So the overhead of tracing is very small, and no regression when using
      those trace events vs blktrace.
      
      And the binary output of TRACE_EVENT is much smaller than blktrace:
      
       # ls -l -h
       -rw-r--r-- 1 root root 8.8M 06-09 13:24 sda.blktrace.0
       -rw-r--r-- 1 root root 195K 06-09 13:24 sda.blktrace.1
       -rw-r--r-- 1 root root 2.7M 06-09 13:25 trace_splice.out
      
      Following are some comparisons between TRACE_EVENT and blktrace:
      
      plug:
        kjournald-480   [000]   303.084981: block_plug: [kjournald]
        kjournald-480   [000]   303.084981:   8,0    P   N [kjournald]
      
      unplug_io:
        kblockd/0-118   [000]   300.052973: block_unplug_io: [kblockd/0] 1
        kblockd/0-118   [000]   300.052974:   8,0    U   N [kblockd/0] 1
      
      remap:
        kjournald-480   [000]   303.085042: block_remap: 8,0 W 102736992 + 8 <- (8,8) 33384
        kjournald-480   [000]   303.085043:   8,0    A   W 102736992 + 8 <- (8,8) 33384
      
      bio_backmerge:
        kjournald-480   [000]   303.085086: block_bio_backmerge: 8,0 W 102737032 + 8 [kjournald]
        kjournald-480   [000]   303.085086:   8,0    M   W 102737032 + 8 [kjournald]
      
      getrq:
        kjournald-480   [000]   303.084974: block_getrq: 8,0 W 102736984 + 8 [kjournald]
        kjournald-480   [000]   303.084975:   8,0    G   W 102736984 + 8 [kjournald]
      
        bash-2066  [001]  1072.953770:   8,0    G   N [bash]
        bash-2066  [001]  1072.953773: block_getrq: 0,0 N 0 + 0 [bash]
      
      rq_complete:
        konsole-2065  [001]   300.053184: block_rq_complete: 8,0 W () 103669040 + 16 [0]
        konsole-2065  [001]   300.053191:   8,0    C   W 103669040 + 16 [0]
      
        ksoftirqd/1-7   [001]  1072.953811:   8,0    C   N (5a 00 08 00 00 00 00 00 24 00) [0]
        ksoftirqd/1-7   [001]  1072.953813: block_rq_complete: 0,0 N (5a 00 08 00 00 00 00 00 24 00) 0 + 0 [0]
      
      rq_insert:
        kjournald-480   [000]   303.084985: block_rq_insert: 8,0 W 0 () 102736984 + 8 [kjournald]
        kjournald-480   [000]   303.084986:   8,0    I   W 102736984 + 8 [kjournald]
      
      Changelog from v2 -> v3:
      
      - use the newly introduced __dynamic_array().
      
      Changelog from v1 -> v2:
      
      - use __string() instead of __array() to minimize the memory required
        to store hex dump of rq->cmd().
      
      - support large pc requests.
      
      - add missing blk_fill_rwbs_rq() in block_rq_requeue TRACE_EVENT.
      
      - some cleanups.
      Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
      LKML-Reference: <4A2DF669.5070905@cn.fujitsu.com>
      Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      55782138
  4. 06 5月, 2009 1 次提交
  5. 15 4月, 2009 1 次提交
  6. 09 4月, 2009 8 次提交
  7. 03 4月, 2009 10 次提交
  8. 17 3月, 2009 1 次提交
    • M
      dm crypt: wait for endio to complete before destruction · b35f8caa
      Milan Broz 提交于
      The following oops has been reported when dm-crypt runs over a loop device.
      
      ...
      [   70.381058] Process loop0 (pid: 4268, ti=cf3b2000 task=cf1cc1f0 task.ti=cf3b2000)
      ...
      [   70.381058] Call Trace:
      [   70.381058]  [<d0d76601>] ? crypt_dec_pending+0x5e/0x62 [dm_crypt]
      [   70.381058]  [<d0d767b8>] ? crypt_endio+0xa2/0xaa [dm_crypt]
      [   70.381058]  [<d0d76716>] ? crypt_endio+0x0/0xaa [dm_crypt]
      [   70.381058]  [<c01a2f24>] ? bio_endio+0x2b/0x2e
      [   70.381058]  [<d0806530>] ? dec_pending+0x224/0x23b [dm_mod]
      [   70.381058]  [<d08066e4>] ? clone_endio+0x79/0xa4 [dm_mod]
      [   70.381058]  [<d080666b>] ? clone_endio+0x0/0xa4 [dm_mod]
      [   70.381058]  [<c01a2f24>] ? bio_endio+0x2b/0x2e
      [   70.381058]  [<c02bad86>] ? loop_thread+0x380/0x3b7
      [   70.381058]  [<c02ba8a1>] ? do_lo_send_aops+0x0/0x165
      [   70.381058]  [<c013754f>] ? autoremove_wake_function+0x0/0x33
      [   70.381058]  [<c02baa06>] ? loop_thread+0x0/0x3b7
      
      When a table is being replaced, it waits for I/O to complete
      before destroying the mempool, but the endio function doesn't
      call mempool_free() until after completing the bio.
      
      Fix it by swapping the order of those two operations.
      
      The same problem occurs in dm.c with md referenced after dec_pending.
      Again, we swap the order.
      
      Cc: stable@kernel.org
      Signed-off-by: NMilan Broz <mbroz@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      b35f8caa
  9. 06 1月, 2009 5 次提交
    • M
      dm: add name and uuid to sysfs · 784aae73
      Milan Broz 提交于
      Implement simple read-only sysfs entry for device-mapper block device.
      
      This patch adds a simple sysfs directory named "dm" under block device
      properties and implements
      	- name attribute (string containing mapped device name)
      	- uuid attribute (string containing UUID, or empty string if not set)
      
      The kobject is embedded in mapped_device struct, so no additional
      memory allocation is needed for initializing sysfs entry.
      
      During the processing of sysfs attribute we need to lock mapped device
      which is done by a new function dm_get_from_kobj, which returns the md
      associated with kobject and increases the usage count.
      
      Each 'show attribute' function is responsible for its own locking.
      Signed-off-by: NMilan Broz <mbroz@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      784aae73
    • M
      dm table: rework reference counting · d5816876
      Mikulas Patocka 提交于
      Rework table reference counting.
      
      The existing code uses a reference counter. When the last reference is
      dropped and the counter reaches zero, the table destructor is called.
      Table reference counters are acquired/released from upcalls from other
      kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
      If the reference counter reaches zero in one of the upcalls, the table
      destructor is called from almost random kernel code.
      
      This leads to various problems:
      * dm_any_congested being called under a spinlock, which calls the
        destructor, which calls some sleeping function.
      * the destructor attempting to take a lock that is already taken by the
        same process.
      * stale reference from some other kernel code keeps the table
        constructed, which keeps some devices open, even after successful
        return from "dmsetup remove". This can confuse lvm and prevent closing
        of underlying devices or reusing device minor numbers.
      
      The patch changes reference counting so that the table destructor can be
      called only at predetermined places.
      
      The table has always exactly one reference from either mapped_device->map
      or hash_cell->new_map. After this patch, this reference is not counted
      in table->holders.  A pair of dm_create_table/dm_destroy_table functions
      is used for table creation/destruction.
      
      Temporary references from the other code increase table->holders. A pair
      of dm_table_get/dm_table_put functions is used to manipulate it.
      
      When the table is about to be destroyed, we wait for table->holders to
      reach 0. Then, we call the table destructor.  We use active waiting with
      msleep(1), because the situation happens rarely (to one user in 5 years)
      and removing the device isn't performance-critical task: the user doesn't
      care if it takes one tick more or not.
      
      This way, the destructor is called only at specific points
      (dm_table_destroy function) and the above problems associated with lazy
      destruction can't happen.
      
      Finally remove the temporary protection added to dm_any_congested().
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      d5816876
    • A
      dm: support barriers on simple devices · ab4c1424
      Andi Kleen 提交于
      Implement barrier support for single device DM devices
      
      This patch implements barrier support in DM for the common case of dm linear
      just remapping a single underlying device. In this case we can safely
      pass the barrier through because there can be no reordering between
      devices.
      
       NB. Any DM device might cease to support barriers if it gets
           reconfigured so code must continue to allow for a possible
           -EOPNOTSUPP on every barrier bio submitted.  - agk
      Signed-off-by: NAndi Kleen <ak@suse.de>
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      ab4c1424
    • K
      dm request: add caches · 8fbf26ad
      Kiyoshi Ueda 提交于
      This patch prepares some kmem_caches for request-based dm.
      Signed-off-by: NKiyoshi Ueda <k-ueda@ct.jp.nec.com>
      Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      8fbf26ad
    • M
      dm table: drop reference at unbind · a1b51e98
      Mikulas Patocka 提交于
      Move one dm_table_put() so that the last reference in the thread
      gets dropped in __unbind().
      
      This is required for a following patch,
      dm-table-rework-reference-counting.patch, which will change the logic in
      such a way that table destructor is called only at specific points in
      the code.
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      a1b51e98
  10. 29 12月, 2008 1 次提交
    • J
      bio: allow individual slabs in the bio_set · bb799ca0
      Jens Axboe 提交于
      Instead of having a global bio slab cache, add a reference to one
      in each bio_set that is created. This allows for personalized slabs
      in each bio_set, so that they can have bios of different sizes.
      
      This means we can personalize the bios we return. File systems may
      want to embed the bio inside another structure, to avoid allocation
      more items (and stuffing them in ->bi_private) after the get a bio.
      Or we may want to embed a number of bio_vecs directly at the end
      of a bio, to avoid doing two allocations to return a bio. This is now
      possible.
      Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
      bb799ca0
  11. 26 11月, 2008 2 次提交
  12. 14 11月, 2008 2 次提交
  13. 22 10月, 2008 3 次提交