mirror_zfs/module
Brian Behlendorf ac09630d8b
Fix zpl_mount() deadlock
Commit 93b43af10 inadvertently introduced the following scenario which
can result in a deadlock.  This issue was most easily reproduced by
LXD containers using a ZFS storage backend but should be reproducible
under any workload which is frequently mounting and unmounting.

-- THREAD A --
spa_sync()
  spa_sync_upgrades()
    rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG); <- Waiting on B

-- THREAD B --
mount_fs()
  zpl_mount()
    zpl_mount_impl()
      dmu_objset_hold()
        dmu_objset_hold_flags()
          dsl_pool_hold()
            dsl_pool_config_enter()
              rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
    sget()
      sget_userns()
        grab_super()
          down_write(&s->s_umount); <- Waiting on C

-- THREAD C --
cleanup_mnt()
  deactivate_super()
    down_write(&s->s_umount);
    deactivate_locked_super()
      zpl_kill_sb()
        kill_anon_super()
          generic_shutdown_super()
            sync_filesystem()
              zpl_sync_fs()
                zfs_sync()
                  zil_commit()
                    txg_wait_synced() <- Waiting on A

Reviewed by: Alek Pinchuk <apinchuk@datto.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #7598 
Closes #7659 
Closes #7691 
Closes #7693
2018-07-11 15:49:10 -07:00
..
avl Update build system and packaging 2018-05-29 16:00:33 -07:00
icp Fix kernel unaligned access on sparc64 2018-07-11 13:10:40 -07:00
lua Update build system and packaging 2018-05-29 16:00:33 -07:00
nvpair Update build system and packaging 2018-05-29 16:00:33 -07:00
spl Add pool state /proc entry, "SUSPENDED" pools 2018-06-06 09:33:54 -07:00
unicode Update build system and packaging 2018-05-29 16:00:33 -07:00
zcommon OpenZFS 9330 - stack overflow when creating a deeply nested dataset 2018-07-09 13:02:50 -07:00
zfs Fix zpl_mount() deadlock 2018-07-11 15:49:10 -07:00
.gitignore Prepare SPL repo to merge with ZFS repo 2018-05-29 14:51:39 -07:00
Makefile.in Update build system and packaging 2018-05-29 16:00:33 -07:00