[bacula/bacula] / bacula / src / stored / device.c

/*
   Bacula® - The Network Backup Solution

   Copyright (C) 2000-2007 Free Software Foundation Europe e.V.

   The main author of Bacula is Kern Sibbald, with contributions from
   many others, a complete list can be found in the file AUTHORS.
   This program is Free Software; you can redistribute it and/or
   modify it under the terms of version two of the GNU General Public
   License as published by the Free Software Foundation and included
   in the file LICENSE.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

   Bacula® is a registered trademark of John Walker.
   The licensor of Bacula is the Free Software Foundation Europe
   (FSFE), Fiduciary Program, Sumatrastrasse 25, 8006 Zürich,
   Switzerland, email:ftf@fsfeurope.org.
*/
/*
 *
 *  Higher Level Device routines.
 *  Knows about Bacula tape labels and such
 *
 *  NOTE! In general, subroutines that have the word
 *        "device" in the name do locking.  Subroutines
 *        that have the word "dev" in the name do not
 *        do locking.  Thus if xxx_device() calls
 *        yyy_dev(), all is OK, but if xxx_device()
 *        calls yyy_device(), everything will hang.
 *        Obviously, no zzz_dev() is allowed to call
 *        a www_device() or everything falls apart.
 *
 * Concerning the routines dev->r_lock()() and block_device()
 *  see the end of this module for details.  In general,
 *  blocking a device leaves it in a state where all threads
 *  other than the current thread block when they attempt to
 *  lock the device. They remain suspended (blocked) until the device
 *  is unblocked. So, a device is blocked during an operation
 *  that takes a long time (initialization, mounting a new
 *  volume, ...) locking a device is done for an operation
 *  that takes a short time such as writing data to the
 *  device.
 *
 *
 *   Kern Sibbald, MM, MMI
 *
 *   Version $Id$
 */

#include "bacula.h"                   /* pull in global headers */
#include "stored.h"                   /* pull in Storage Deamon headers */

#ifdef SD_DEBUG_LOCK
const int dbglvl = 0;
#else
const int dbglvl = 500;
#endif


/* Forward referenced functions */

/*
 * This is the dreaded moment. We either have an end of
 * medium condition or worse, and error condition.
 * Attempt to "recover" by obtaining a new Volume.
 *
 * Here are a few things to know:
 *  dcr->VolCatInfo contains the info on the "current" tape for this job.
 *  dev->VolCatInfo contains the info on the tape in the drive.
 *    The tape in the drive could have changed several times since
 *    the last time the job used it (jcr->VolCatInfo).
 *  dcr->VolumeName is the name of the current/desired tape in the drive.
 *
 * We enter with device locked, and
 *     exit with device locked.
 *
 * Note, we are called only from one place in block.c for the daemons.  
 *     The btape utility calls it from btape.c.
 *
 *  Returns: true  on success
 *           false on failure
 */
bool fixup_device_block_write_error(DCR *dcr)
{
   char PrevVolName[MAX_NAME_LENGTH];
   DEV_BLOCK *label_blk;
   DEV_BLOCK *block = dcr->block;
   char b1[30], b2[30];
   time_t wait_time;
   char dt[MAX_TIME_LENGTH];
   JCR *jcr = dcr->jcr;
   DEVICE *dev = dcr->dev;

   wait_time = time(NULL);

   Dmsg0(100, "Enter fixup_device_block_write_error\n");

   block_device(dev, BST_DOING_ACQUIRE);
   /* Unlock, but leave BLOCKED */
   dev->dunlock();

   bstrncpy(PrevVolName, dev->VolCatInfo.VolCatName, sizeof(PrevVolName));
   bstrncpy(dev->VolHdr.PrevVolumeName, PrevVolName, sizeof(dev->VolHdr.PrevVolumeName));

   label_blk = new_block(dev);
   dcr->block = label_blk;

   /* Inform User about end of medium */
   Jmsg(jcr, M_INFO, 0, _("End of medium on Volume \"%s\" Bytes=%s Blocks=%s at %s.\n"),
        PrevVolName, edit_uint64_with_commas(dev->VolCatInfo.VolCatBytes, b1),
        edit_uint64_with_commas(dev->VolCatInfo.VolCatBlocks, b2),
        bstrftime(dt, sizeof(dt), time(NULL)));

   if (!mount_next_write_volume(dcr, 1)) {
      free_block(label_blk);
      dcr->block = block;
      dev->dlock();  
      unblock_device(dev);
      return false;                /* device locked */
   }
   dev->dlock();                    /* lock again */

   dev->VolCatInfo.VolCatJobs++;              /* increment number of jobs on vol */
   dir_update_volume_info(dcr, false);        /* send Volume info to Director */

   Jmsg(jcr, M_INFO, 0, _("New volume \"%s\" mounted on device %s at %s.\n"),
      dcr->VolumeName, dev->print_name(), bstrftime(dt, sizeof(dt), time(NULL)));

   /*
    * If this is a new tape, the label_blk will contain the
    *  label, so write it now. If this is a previously
    *  used tape, mount_next_write_volume() will return an
    *  empty label_blk, and nothing will be written.
    */
   Dmsg0(190, "write label block to dev\n");
   if (!write_block_to_dev(dcr)) {
      berrno be;
      Pmsg1(0, _("write_block_to_device Volume label failed. ERR=%s"),
        be.bstrerror(dev->dev_errno));
      free_block(label_blk);
      dcr->block = block;
      unblock_device(dev);
      return false;                /* device locked */
   }
   free_block(label_blk);
   dcr->block = block;

   /*
    * Walk through all attached jcrs indicating the volume has changed
    */
   Dmsg1(100, "Walk attached dcrs. Volume=%s\n", dev->VolCatInfo.VolCatName);
   DCR *mdcr;
   foreach_dlist(mdcr, dev->attached_dcrs) {
      JCR *mjcr = mdcr->jcr;
      if (mjcr->JobId == 0) {
         continue;                 /* ignore console */
      }
      mdcr->NewVol = true;
      if (jcr != mjcr) {
         bstrncpy(mdcr->VolumeName, dcr->VolumeName, sizeof(mdcr->VolumeName));
      }
   }

   /* Clear NewVol now because dir_get_volume_info() already done */
   jcr->dcr->NewVol = false;
   set_new_volume_parameters(dcr);

   jcr->run_time += time(NULL) - wait_time; /* correct run time for mount wait */

   /* Write overflow block to device */
   Dmsg0(190, "Write overflow block to dev\n");
   if (!write_block_to_dev(dcr)) {
      berrno be;
      Pmsg1(0, _("write_block_to_device overflow block failed. ERR=%s"),
        be.bstrerror(dev->dev_errno));
      unblock_device(dev);
      return false;                /* device locked */
   }

   unblock_device(dev);
   return true;                             /* device locked */
}

/*
 * We have a new Volume mounted, so reset the Volume parameters
 *  concerning this job.  The global changes were made earlier
 *  in the dev structure.
 */
void set_new_volume_parameters(DCR *dcr)
{
   JCR *jcr = dcr->jcr;
   DEVICE *dev = dcr->dev;
   if (dcr->NewVol && !dir_get_volume_info(dcr, GET_VOL_INFO_FOR_WRITE)) {
      Jmsg1(jcr, M_ERROR, 0, "%s", jcr->errmsg);
   }
   /* Set new start/end positions */
   if (dev->is_tape()) {
      dcr->StartBlock = dev->block_num;
      dcr->StartFile = dev->file;
   } else {
      dcr->StartBlock = (uint32_t)dev->file_addr;
      dcr->StartFile  = (uint32_t)(dev->file_addr >> 32);
   }
   /* Reset indicies */
   dcr->VolFirstIndex = 0;
   dcr->VolLastIndex = 0;
   jcr->NumWriteVolumes++;
   dcr->NewVol = false;
   dcr->WroteVol = false;
}

/*
 * We are now in a new Volume file, so reset the Volume parameters
 *  concerning this job.  The global changes were made earlier
 *  in the dev structure.
 */
void set_new_file_parameters(DCR *dcr)
{
   DEVICE *dev = dcr->dev;

   /* Set new start/end positions */
   if (dev->is_tape()) {
      dcr->StartBlock = dev->block_num;
      dcr->StartFile = dev->file;
   } else {
      dcr->StartBlock = (uint32_t)dev->file_addr;
      dcr->StartFile  = (uint32_t)(dev->file_addr >> 32);
   }
   /* Reset indicies */
   dcr->VolFirstIndex = 0;
   dcr->VolLastIndex = 0;
   dcr->NewFile = false;
   dcr->WroteVol = false;
}



/*
 *   First Open of the device. Expect dev to already be initialized.
 *
 *   This routine is used only when the Storage daemon starts
 *   and always_open is set, and in the stand-alone utility
 *   routines such as bextract.
 *
 *   Note, opening of a normal file is deferred to later so
 *    that we can get the filename; the device_name for
 *    a file is the directory only.
 *
 *   Returns: false on failure
 *            true  on success
 */
bool first_open_device(DCR *dcr)
{
   DEVICE *dev = dcr->dev;
   bool ok = true;

   Dmsg0(120, "start open_output_device()\n");
   if (!dev) {
      return false;
   }

   dev->r_dlock();

   /* Defer opening files */
   if (!dev->is_tape()) {
      Dmsg0(129, "Device is file, deferring open.\n");
      goto bail_out;
   }

    int mode;
    if (dev->has_cap(CAP_STREAM)) {
       mode = OPEN_WRITE_ONLY;
    } else {
       mode = OPEN_READ_ONLY;
    }
   Dmsg0(129, "Opening device.\n");
   if (dev->open(dcr, mode) < 0) {
      Emsg1(M_FATAL, 0, _("dev open failed: %s\n"), dev->errmsg);
      ok = false;
      goto bail_out;
   }
   Dmsg1(129, "open dev %s OK\n", dev->print_name());

bail_out:
   dev->dunlock();
   return ok;
}

/*
 * Make sure device is open, if not do so
 */
bool open_device(DCR *dcr)
{
   DEVICE *dev = dcr->dev;
   /* Open device */
   int mode;
   if (dev->has_cap(CAP_STREAM)) {
      mode = OPEN_WRITE_ONLY;
   } else {
      mode = OPEN_READ_WRITE;
   }
   if (dev->open(dcr, mode) < 0) {
      /* If polling, ignore the error */
      /* If DVD, also ignore the error, very often you cannot open the device
       * (when there is no DVD, or when the one inserted is a wrong one) */
      if (!dev->poll && !dev->is_dvd() && !dev->is_removable()) {
         Jmsg2(dcr->jcr, M_FATAL, 0, _("Unable to open device %s: ERR=%s\n"),
            dev->print_name(), dev->bstrerror());
         Pmsg2(000, _("Unable to open archive %s: ERR=%s\n"), 
            dev->print_name(), dev->bstrerror());
      }
      return false;
   }
   return true;
}


/*
 * Check if the device is blocked or not
 */
bool is_device_unmounted(DEVICE *dev)
{
   bool stat;
   int blocked = dev->blocked();
   stat = (blocked == BST_UNMOUNTED) ||
          (blocked == BST_UNMOUNTED_WAITING_FOR_SYSOP);
   return stat;
}

#ifdef SD_DEBUG_LOCK
void DEVICE::_dlock(const char *file, int line)
{
   Dmsg4(sd_dbglvl, "dlock from %s:%d precnt=%d JobId=%u\n", file, line,
         m_count, get_jobid_from_tid()); 
   /* Note, this *really* should be protected by a mutex, but
    *  since it is only debug code we don't worry too much.  
    */
   if (m_count > 0 && pthread_equal(m_pid, pthread_self())) {
      Dmsg5(sd_dbglvl, "Possible DEADLOCK!! lock held by JobId=%u from %s:%d m_count=%d JobId=%u\n", 
            get_jobid_from_tid(m_pid),
            file, line, m_count, get_jobid_from_tid());
   }
   P(m_mutex);
   m_pid = pthread_self();
   m_count++; 
}

void DEVICE::_dunlock(const char *file, int line)
{
   m_count--; 
   Dmsg4(sd_dbglvl+1, "dunlock from %s:%d postcnt=%d JobId=%u\n", file, line,
         m_count, get_jobid_from_tid()); 
   V(m_mutex);   
}

void DEVICE::_r_dunlock(const char *file, int line)
{
   this->_dunlock(file, line);
}

#endif


/*
 * This is a recursive lock that checks if the device is blocked.
 *
 * When blocked is set, all threads EXCEPT thread with id no_wait_id
 * must wait. The no_wait_id thread is out obtaining a new volume
 * and preparing the label.
 */
#ifdef SD_DEBUG_LOCK
void DEVICE::_r_dlock(const char *file, int line)
#else
void DEVICE::r_dlock()
#endif
{
   int stat;
#ifdef SD_DEBUG_LOCK
   Dmsg4(sd_dbglvl+1, "r_dlock blked=%s from %s:%d JobId=%u\n", this->print_blocked(),
         file, line, get_jobid_from_tid());
#else
   Dmsg1(sd_dbglvl, "reclock blked=%s\n", this->print_blocked());
#endif
   this->dlock();   
   if (this->blocked() && !pthread_equal(this->no_wait_id, pthread_self())) {
      this->num_waiting++;             /* indicate that I am waiting */
      while (this->blocked()) {
         Dmsg3(sd_dbglvl, "r_dlock blked=%s no_wait=%p me=%p\n", this->print_blocked(),
               this->no_wait_id, pthread_self());
         if ((stat = pthread_cond_wait(&this->wait, &m_mutex)) != 0) {
            berrno be;
            this->dunlock();
            Emsg1(M_ABORT, 0, _("pthread_cond_wait failure. ERR=%s\n"),
               be.bstrerror(stat));
         }
      }
      this->num_waiting--;             /* no longer waiting */
   }
}

/*
 * Block all other threads from using the device
 *  Device must already be locked.  After this call,
 *  the device is blocked to any thread calling dev->r_lock(),
 *  but the device is not locked (i.e. no P on device).  Also,
 *  the current thread can do slip through the dev->r_lock()
 *  calls without blocking.
 */
void _block_device(const char *file, int line, DEVICE *dev, int state)
{
   ASSERT(dev->blocked() == BST_NOT_BLOCKED);
   dev->set_blocked(state);           /* make other threads wait */
   dev->no_wait_id = pthread_self();  /* allow us to continue */
   Dmsg3(sd_dbglvl, "set blocked=%s from %s:%d\n", dev->print_blocked(), file, line);
}

/*
 * Unblock the device, and wake up anyone who went to sleep.
 * Enter: device locked
 * Exit:  device locked
 */
void _unblock_device(const char *file, int line, DEVICE *dev)
{
   Dmsg3(sd_dbglvl, "unblock %s from %s:%d\n", dev->print_blocked(), file, line);
   ASSERT(dev->blocked());
   dev->set_blocked(BST_NOT_BLOCKED);
   dev->no_wait_id = 0;
   if (dev->num_waiting > 0) {
      pthread_cond_broadcast(&dev->wait); /* wake them up */
   }
}

/*
 * Enter with device locked and blocked
 * Exit with device unlocked and blocked by us.
 */
void _steal_device_lock(const char *file, int line, DEVICE *dev, bsteal_lock_t *hold, int state)
{

   Dmsg3(sd_dbglvl, "steal lock. old=%s from %s:%d\n", dev->print_blocked(),
      file, line);
   hold->dev_blocked = dev->blocked();
   hold->dev_prev_blocked = dev->dev_prev_blocked;
   hold->no_wait_id = dev->no_wait_id;
   dev->set_blocked(state);
   Dmsg1(sd_dbglvl, "steal lock. new=%s\n", dev->print_blocked());
   dev->no_wait_id = pthread_self();
   dev->dunlock();
}

/*
 * Enter with device blocked by us but not locked
 * Exit with device locked, and blocked by previous owner
 */
void _give_back_device_lock(const char *file, int line, DEVICE *dev, bsteal_lock_t *hold)
{
   Dmsg3(sd_dbglvl, "return lock. old=%s from %s:%d\n",
      dev->print_blocked(), file, line);
   dev->dlock();
   dev->set_blocked(hold->dev_blocked);
   dev->dev_prev_blocked = hold->dev_prev_blocked;
   dev->no_wait_id = hold->no_wait_id;
   Dmsg1(sd_dbglvl, "return lock. new=%s\n", dev->print_blocked());
   if (dev->num_waiting > 0) {
      pthread_cond_broadcast(&dev->wait); /* wake them up */
   }
}