/*
   * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   * Copyright 2004-2011 Red Hat, Inc.
   *
   * This copyrighted material is made available to anyone wishing to use,
   * modify, copy, or redistribute it subject to the terms and conditions
   * of the GNU General Public License version 2.
   */
  
  #include <linux/fs.h>
  #include <linux/dlm.h>
  #include <linux/slab.h>
  #include <linux/types.h>
  #include <linux/delay.h>
  #include <linux/gfs2_ondisk.h>
  
  #include "incore.h"
  #include "glock.h"
  #include "util.h"
  #include "sys.h"
  #include "trace_gfs2.h"
  
  extern struct workqueue_struct *gfs2_control_wq;
  
  /**
   * gfs2_update_stats - Update time based stats
   * @mv: Pointer to mean/variance structure to update
   * @sample: New data to include
   *
   * @delta is the difference between the current rtt sample and the
   * running average srtt. We add 1/8 of that to the srtt in order to
   * update the current srtt estimate. The varience estimate is a bit
   * more complicated. We subtract the abs value of the @delta from
   * the current variance estimate and add 1/4 of that to the running
   * total.
   *
   * Note that the index points at the array entry containing the smoothed
   * mean value, and the variance is always in the following entry
   *
   * Reference: TCP/IP Illustrated, vol 2, p. 831,832
   * All times are in units of integer nanoseconds. Unlike the TCP/IP case,
   * they are not scaled fixed point.
   */
  
  static inline void gfs2_update_stats(struct gfs2_lkstats *s, unsigned index,
  				     s64 sample)
  {
  	s64 delta = sample - s->stats[index];
  	s->stats[index] += (delta >> 3);
  	index++;
  	s->stats[index] += ((abs64(delta) - s->stats[index]) >> 2);
  }
  
  /**
   * gfs2_update_reply_times - Update locking statistics
   * @gl: The glock to update
   *
   * This assumes that gl->gl_dstamp has been set earlier.
   *
   * The rtt (lock round trip time) is an estimate of the time
   * taken to perform a dlm lock request. We update it on each
   * reply from the dlm.
   *
   * The blocking flag is set on the glock for all dlm requests
   * which may potentially block due to lock requests from other nodes.
   * DLM requests where the current lock state is exclusive, the
   * requested state is null (or unlocked) or where the TRY or
   * TRY_1CB flags are set are classified as non-blocking. All
   * other DLM requests are counted as (potentially) blocking.
   */
  static inline void gfs2_update_reply_times(struct gfs2_glock *gl)
  {
  	struct gfs2_pcpu_lkstats *lks;
  	const unsigned gltype = gl->gl_name.ln_type;
  	unsigned index = test_bit(GLF_BLOCKING, &gl->gl_flags) ?
  			 GFS2_LKS_SRTTB : GFS2_LKS_SRTT;
  	s64 rtt;
  
  	preempt_disable();
  	rtt = ktime_to_ns(ktime_sub(ktime_get_real(), gl->gl_dstamp));
  	lks = this_cpu_ptr(gl->gl_sbd->sd_lkstats);
  	gfs2_update_stats(&gl->gl_stats, index, rtt);		/* Local */
  	gfs2_update_stats(&lks->lkstats[gltype], index, rtt);	/* Global */
  	preempt_enable();
  
  	trace_gfs2_glock_lock_time(gl, rtt);
  }
  
  /**
   * gfs2_update_request_times - Update locking statistics
   * @gl: The glock to update
   *
   * The irt (lock inter-request times) measures the average time
   * between requests to the dlm. It is updated immediately before
   * each dlm call.
   */
  
  static inline void gfs2_update_request_times(struct gfs2_glock *gl)
  {
  	struct gfs2_pcpu_lkstats *lks;
  	const unsigned gltype = gl->gl_name.ln_type;
  	ktime_t dstamp;
  	s64 irt;
  
  	preempt_disable();
  	dstamp = gl->gl_dstamp;
  	gl->gl_dstamp = ktime_get_real();
  	irt = ktime_to_ns(ktime_sub(gl->gl_dstamp, dstamp));
  	lks = this_cpu_ptr(gl->gl_sbd->sd_lkstats);
  	gfs2_update_stats(&gl->gl_stats, GFS2_LKS_SIRT, irt);		/* Local */
  	gfs2_update_stats(&lks->lkstats[gltype], GFS2_LKS_SIRT, irt);	/* Global */
  	preempt_enable();
  }
   
  static void gdlm_ast(void *arg)
  {
  	struct gfs2_glock *gl = arg;
  	unsigned ret = gl->gl_state;
  
  	gfs2_update_reply_times(gl);
  	BUG_ON(gl->gl_lksb.sb_flags & DLM_SBF_DEMOTED);
  
  	if ((gl->gl_lksb.sb_flags & DLM_SBF_VALNOTVALID) && gl->gl_lksb.sb_lvbptr)
  		memset(gl->gl_lksb.sb_lvbptr, 0, GDLM_LVB_SIZE);
  
  	switch (gl->gl_lksb.sb_status) {
  	case -DLM_EUNLOCK: /* Unlocked, so glock can be freed */
  		gfs2_glock_free(gl);
  		return;
  	case -DLM_ECANCEL: /* Cancel while getting lock */
  		ret |= LM_OUT_CANCELED;
  		goto out;
  	case -EAGAIN: /* Try lock fails */
  	case -EDEADLK: /* Deadlock detected */
  		goto out;
  	case -ETIMEDOUT: /* Canceled due to timeout */
  		ret |= LM_OUT_ERROR;
  		goto out;
  	case 0: /* Success */
  		break;
  	default: /* Something unexpected */
  		BUG();
  	}
  
  	ret = gl->gl_req;
  	if (gl->gl_lksb.sb_flags & DLM_SBF_ALTMODE) {
  		if (gl->gl_req == LM_ST_SHARED)
  			ret = LM_ST_DEFERRED;
  		else if (gl->gl_req == LM_ST_DEFERRED)
  			ret = LM_ST_SHARED;
  		else
  			BUG();
  	}
  
  	set_bit(GLF_INITIAL, &gl->gl_flags);
  	gfs2_glock_complete(gl, ret);
  	return;
  out:
  	if (!test_bit(GLF_INITIAL, &gl->gl_flags))
  		gl->gl_lksb.sb_lkid = 0;
  	gfs2_glock_complete(gl, ret);
  }
  
  static void gdlm_bast(void *arg, int mode)
  {
  	struct gfs2_glock *gl = arg;
  
  	switch (mode) {
  	case DLM_LOCK_EX:
  		gfs2_glock_cb(gl, LM_ST_UNLOCKED);
  		break;
  	case DLM_LOCK_CW:
  		gfs2_glock_cb(gl, LM_ST_DEFERRED);
  		break;
  	case DLM_LOCK_PR:
  		gfs2_glock_cb(gl, LM_ST_SHARED);
  		break;
  	default:
  		printk(KERN_ERR "unknown bast mode %d", mode);
  		BUG();
  	}
  }
  
  /* convert gfs lock-state to dlm lock-mode */
  
  static int make_mode(const unsigned int lmstate)
  {
  	switch (lmstate) {
  	case LM_ST_UNLOCKED:
  		return DLM_LOCK_NL;
  	case LM_ST_EXCLUSIVE:
  		return DLM_LOCK_EX;
  	case LM_ST_DEFERRED:
  		return DLM_LOCK_CW;
  	case LM_ST_SHARED:
  		return DLM_LOCK_PR;
  	}
  	printk(KERN_ERR "unknown LM state %d", lmstate);
  	BUG();
  	return -1;
  }
  
  static u32 make_flags(struct gfs2_glock *gl, const unsigned int gfs_flags,
  		      const int req)
  {
  	u32 lkf = 0;
  
  	if (gl->gl_lksb.sb_lvbptr)
  		lkf |= DLM_LKF_VALBLK;
  
  	if (gfs_flags & LM_FLAG_TRY)
  		lkf |= DLM_LKF_NOQUEUE;
  
  	if (gfs_flags & LM_FLAG_TRY_1CB) {
  		lkf |= DLM_LKF_NOQUEUE;
  		lkf |= DLM_LKF_NOQUEUEBAST;
  	}
  
  	if (gfs_flags & LM_FLAG_PRIORITY) {
  		lkf |= DLM_LKF_NOORDER;
  		lkf |= DLM_LKF_HEADQUE;
  	}
  
  	if (gfs_flags & LM_FLAG_ANY) {
  		if (req == DLM_LOCK_PR)
  			lkf |= DLM_LKF_ALTCW;
  		else if (req == DLM_LOCK_CW)
  			lkf |= DLM_LKF_ALTPR;
  		else
  			BUG();
  	}
  
  	if (gl->gl_lksb.sb_lkid != 0) {
  		lkf |= DLM_LKF_CONVERT;
  		if (test_bit(GLF_BLOCKING, &gl->gl_flags))
  			lkf |= DLM_LKF_QUECVT;
  	}
  
  	return lkf;
  }
  
  static void gfs2_reverse_hex(char *c, u64 value)
  {
  	*c = '0';
  	while (value) {
  		*c-- = hex_asc[value & 0x0f];
  		value >>= 4;
  	}
  }
  
  static int gdlm_lock(struct gfs2_glock *gl, unsigned int req_state,
  		     unsigned int flags)
  {
  	struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
  	int req;
  	u32 lkf;
  	char strname[GDLM_STRNAME_BYTES] = "";
  
  	req = make_mode(req_state);
  	lkf = make_flags(gl, flags, req);
  	gfs2_glstats_inc(gl, GFS2_LKS_DCOUNT);
  	gfs2_sbstats_inc(gl, GFS2_LKS_DCOUNT);
  	if (gl->gl_lksb.sb_lkid) {
  		gfs2_update_request_times(gl);
  	} else {
  		memset(strname, ' ', GDLM_STRNAME_BYTES - 1);
  		strname[GDLM_STRNAME_BYTES - 1] = '\0';
  		gfs2_reverse_hex(strname + 7, gl->gl_name.ln_type);
  		gfs2_reverse_hex(strname + 23, gl->gl_name.ln_number);
  		gl->gl_dstamp = ktime_get_real();
  	}
  	/*
  	 * Submit the actual lock request.
  	 */
  
  	return dlm_lock(ls->ls_dlm, req, &gl->gl_lksb, lkf, strname,
  			GDLM_STRNAME_BYTES - 1, 0, gdlm_ast, gl, gdlm_bast);
  }
  
  static void gdlm_put_lock(struct gfs2_glock *gl)
  {
  	struct gfs2_sbd *sdp = gl->gl_sbd;
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	int lvb_needs_unlock = 0;
  	int error;
  
  	if (gl->gl_lksb.sb_lkid == 0) {
  		gfs2_glock_free(gl);
  		return;
  	}
  
  	clear_bit(GLF_BLOCKING, &gl->gl_flags);
  	gfs2_glstats_inc(gl, GFS2_LKS_DCOUNT);
  	gfs2_sbstats_inc(gl, GFS2_LKS_DCOUNT);
  	gfs2_update_request_times(gl);
  
  	/* don't want to skip dlm_unlock writing the lvb when lock is ex */
  
  	if (gl->gl_lksb.sb_lvbptr && (gl->gl_state == LM_ST_EXCLUSIVE))
  		lvb_needs_unlock = 1;
  
  	if (test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags) &&
  	    !lvb_needs_unlock) {
  		gfs2_glock_free(gl);
  		return;
  	}
  
  	error = dlm_unlock(ls->ls_dlm, gl->gl_lksb.sb_lkid, DLM_LKF_VALBLK,
  			   NULL, gl);
  	if (error) {
  		printk(KERN_ERR "gdlm_unlock %x,%llx err=%d
  ",
  		       gl->gl_name.ln_type,
  		       (unsigned long long)gl->gl_name.ln_number, error);
  		return;
  	}
  }
  
  static void gdlm_cancel(struct gfs2_glock *gl)
  {
  	struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
  	dlm_unlock(ls->ls_dlm, gl->gl_lksb.sb_lkid, DLM_LKF_CANCEL, NULL, gl);
  }
  
  /*
   * dlm/gfs2 recovery coordination using dlm_recover callbacks
   *
   *  1. dlm_controld sees lockspace members change
   *  2. dlm_controld blocks dlm-kernel locking activity
   *  3. dlm_controld within dlm-kernel notifies gfs2 (recover_prep)
   *  4. dlm_controld starts and finishes its own user level recovery
   *  5. dlm_controld starts dlm-kernel dlm_recoverd to do kernel recovery
   *  6. dlm_recoverd notifies gfs2 of failed nodes (recover_slot)
   *  7. dlm_recoverd does its own lock recovery
   *  8. dlm_recoverd unblocks dlm-kernel locking activity
   *  9. dlm_recoverd notifies gfs2 when done (recover_done with new generation)
   * 10. gfs2_control updates control_lock lvb with new generation and jid bits
   * 11. gfs2_control enqueues journals for gfs2_recover to recover (maybe none)
   * 12. gfs2_recover dequeues and recovers journals of failed nodes
   * 13. gfs2_recover provides recovery results to gfs2_control (recovery_result)
   * 14. gfs2_control updates control_lock lvb jid bits for recovered journals
   * 15. gfs2_control unblocks normal locking when all journals are recovered
   *
   * - failures during recovery
   *
   * recover_prep() may set BLOCK_LOCKS (step 3) again before gfs2_control
   * clears BLOCK_LOCKS (step 15), e.g. another node fails while still
   * recovering for a prior failure.  gfs2_control needs a way to detect
   * this so it can leave BLOCK_LOCKS set in step 15.  This is managed using
   * the recover_block and recover_start values.
   *
   * recover_done() provides a new lockspace generation number each time it
   * is called (step 9).  This generation number is saved as recover_start.
   * When recover_prep() is called, it sets BLOCK_LOCKS and sets
   * recover_block = recover_start.  So, while recover_block is equal to
   * recover_start, BLOCK_LOCKS should remain set.  (recover_spin must
   * be held around the BLOCK_LOCKS/recover_block/recover_start logic.)
   *
   * - more specific gfs2 steps in sequence above
   *
   *  3. recover_prep sets BLOCK_LOCKS and sets recover_block = recover_start
   *  6. recover_slot records any failed jids (maybe none)
   *  9. recover_done sets recover_start = new generation number
   * 10. gfs2_control sets control_lock lvb = new gen + bits for failed jids
   * 12. gfs2_recover does journal recoveries for failed jids identified above
   * 14. gfs2_control clears control_lock lvb bits for recovered jids
   * 15. gfs2_control checks if recover_block == recover_start (step 3 occured
   *     again) then do nothing, otherwise if recover_start > recover_block
   *     then clear BLOCK_LOCKS.
   *
   * - parallel recovery steps across all nodes
   *
   * All nodes attempt to update the control_lock lvb with the new generation
   * number and jid bits, but only the first to get the control_lock EX will
   * do so; others will see that it's already done (lvb already contains new
   * generation number.)
   *
   * . All nodes get the same recover_prep/recover_slot/recover_done callbacks
   * . All nodes attempt to set control_lock lvb gen + bits for the new gen
   * . One node gets control_lock first and writes the lvb, others see it's done
   * . All nodes attempt to recover jids for which they see control_lock bits set
   * . One node succeeds for a jid, and that one clears the jid bit in the lvb
   * . All nodes will eventually see all lvb bits clear and unblock locks
   *
   * - is there a problem with clearing an lvb bit that should be set
   *   and missing a journal recovery?
   *
   * 1. jid fails
   * 2. lvb bit set for step 1
   * 3. jid recovered for step 1
   * 4. jid taken again (new mount)
   * 5. jid fails (for step 4)
   * 6. lvb bit set for step 5 (will already be set)
   * 7. lvb bit cleared for step 3
   *
   * This is not a problem because the failure in step 5 does not
   * require recovery, because the mount in step 4 could not have
   * progressed far enough to unblock locks and access the fs.  The
   * control_mount() function waits for all recoveries to be complete
   * for the latest lockspace generation before ever unblocking locks
   * and returning.  The mount in step 4 waits until the recovery in
   * step 1 is done.
   *
   * - special case of first mounter: first node to mount the fs
   *
   * The first node to mount a gfs2 fs needs to check all the journals
   * and recover any that need recovery before other nodes are allowed
   * to mount the fs.  (Others may begin mounting, but they must wait
   * for the first mounter to be done before taking locks on the fs
   * or accessing the fs.)  This has two parts:
   *
   * 1. The mounted_lock tells a node it's the first to mount the fs.
   * Each node holds the mounted_lock in PR while it's mounted.
   * Each node tries to acquire the mounted_lock in EX when it mounts.
   * If a node is granted the mounted_lock EX it means there are no
   * other mounted nodes (no PR locks exist), and it is the first mounter.
   * The mounted_lock is demoted to PR when first recovery is done, so
   * others will fail to get an EX lock, but will get a PR lock.
   *
   * 2. The control_lock blocks others in control_mount() while the first
   * mounter is doing first mount recovery of all journals.
   * A mounting node needs to acquire control_lock in EX mode before
   * it can proceed.  The first mounter holds control_lock in EX while doing
   * the first mount recovery, blocking mounts from other nodes, then demotes
   * control_lock to NL when it's done (others_may_mount/first_done),
   * allowing other nodes to continue mounting.
   *
   * first mounter:
   * control_lock EX/NOQUEUE success
   * mounted_lock EX/NOQUEUE success (no other PR, so no other mounters)
   * set first=1
   * do first mounter recovery
   * mounted_lock EX->PR
   * control_lock EX->NL, write lvb generation
   *
   * other mounter:
   * control_lock EX/NOQUEUE success (if fail -EAGAIN, retry)
   * mounted_lock EX/NOQUEUE fail -EAGAIN (expected due to other mounters PR)
   * mounted_lock PR/NOQUEUE success
   * read lvb generation
   * control_lock EX->NL
   * set first=0
   *
   * - mount during recovery
   *
   * If a node mounts while others are doing recovery (not first mounter),
   * the mounting node will get its initial recover_done() callback without
   * having seen any previous failures/callbacks.
   *
   * It must wait for all recoveries preceding its mount to be finished
   * before it unblocks locks.  It does this by repeating the "other mounter"
   * steps above until the lvb generation number is >= its mount generation
   * number (from initial recover_done) and all lvb bits are clear.
   *
   * - control_lock lvb format
   *
   * 4 bytes generation number: the latest dlm lockspace generation number
   * from recover_done callback.  Indicates the jid bitmap has been updated
   * to reflect all slot failures through that generation.
   * 4 bytes unused.
   * GDLM_LVB_SIZE-8 bytes of jid bit map. If bit N is set, it indicates
   * that jid N needs recovery.
   */
  
  #define JID_BITMAP_OFFSET 8 /* 4 byte generation number + 4 byte unused */
  
  static void control_lvb_read(struct lm_lockstruct *ls, uint32_t *lvb_gen,
  			     char *lvb_bits)
  {
  	__le32 gen;
  	memcpy(lvb_bits, ls->ls_control_lvb, GDLM_LVB_SIZE);
  	memcpy(&gen, lvb_bits, sizeof(__le32));
  	*lvb_gen = le32_to_cpu(gen);
  }
  
  static void control_lvb_write(struct lm_lockstruct *ls, uint32_t lvb_gen,
  			      char *lvb_bits)
  {
  	__le32 gen;
  	memcpy(ls->ls_control_lvb, lvb_bits, GDLM_LVB_SIZE);
  	gen = cpu_to_le32(lvb_gen);
  	memcpy(ls->ls_control_lvb, &gen, sizeof(__le32));
  }
  
  static int all_jid_bits_clear(char *lvb)
  {
  	return !memchr_inv(lvb + JID_BITMAP_OFFSET, 0,
  			GDLM_LVB_SIZE - JID_BITMAP_OFFSET);
  }
  
  static void sync_wait_cb(void *arg)
  {
  	struct lm_lockstruct *ls = arg;
  	complete(&ls->ls_sync_wait);
  }
  
  static int sync_unlock(struct gfs2_sbd *sdp, struct dlm_lksb *lksb, char *name)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	int error;
  
  	error = dlm_unlock(ls->ls_dlm, lksb->sb_lkid, 0, lksb, ls);
  	if (error) {
  		fs_err(sdp, "%s lkid %x error %d
  ",
  		       name, lksb->sb_lkid, error);
  		return error;
  	}
  
  	wait_for_completion(&ls->ls_sync_wait);
  
  	if (lksb->sb_status != -DLM_EUNLOCK) {
  		fs_err(sdp, "%s lkid %x status %d
  ",
  		       name, lksb->sb_lkid, lksb->sb_status);
  		return -1;
  	}
  	return 0;
  }
  
  static int sync_lock(struct gfs2_sbd *sdp, int mode, uint32_t flags,
  		     unsigned int num, struct dlm_lksb *lksb, char *name)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	char strname[GDLM_STRNAME_BYTES];
  	int error, status;
  
  	memset(strname, 0, GDLM_STRNAME_BYTES);
  	snprintf(strname, GDLM_STRNAME_BYTES, "%8x%16x", LM_TYPE_NONDISK, num);
  
  	error = dlm_lock(ls->ls_dlm, mode, lksb, flags,
  			 strname, GDLM_STRNAME_BYTES - 1,
  			 0, sync_wait_cb, ls, NULL);
  	if (error) {
  		fs_err(sdp, "%s lkid %x flags %x mode %d error %d
  ",
  		       name, lksb->sb_lkid, flags, mode, error);
  		return error;
  	}
  
  	wait_for_completion(&ls->ls_sync_wait);
  
  	status = lksb->sb_status;
  
  	if (status && status != -EAGAIN) {
  		fs_err(sdp, "%s lkid %x flags %x mode %d status %d
  ",
  		       name, lksb->sb_lkid, flags, mode, status);
  	}
  
  	return status;
  }
  
  static int mounted_unlock(struct gfs2_sbd *sdp)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	return sync_unlock(sdp, &ls->ls_mounted_lksb, "mounted_lock");
  }
  
  static int mounted_lock(struct gfs2_sbd *sdp, int mode, uint32_t flags)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	return sync_lock(sdp, mode, flags, GFS2_MOUNTED_LOCK,
  			 &ls->ls_mounted_lksb, "mounted_lock");
  }
  
  static int control_unlock(struct gfs2_sbd *sdp)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	return sync_unlock(sdp, &ls->ls_control_lksb, "control_lock");
  }
  
  static int control_lock(struct gfs2_sbd *sdp, int mode, uint32_t flags)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	return sync_lock(sdp, mode, flags, GFS2_CONTROL_LOCK,
  			 &ls->ls_control_lksb, "control_lock");
  }
  
  static void gfs2_control_func(struct work_struct *work)
  {
  	struct gfs2_sbd *sdp = container_of(work, struct gfs2_sbd, sd_control_work.work);
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	uint32_t block_gen, start_gen, lvb_gen, flags;
  	int recover_set = 0;
  	int write_lvb = 0;
  	int recover_size;
  	int i, error;
  
  	spin_lock(&ls->ls_recover_spin);
  	/*
  	 * No MOUNT_DONE means we're still mounting; control_mount()
  	 * will set this flag, after which this thread will take over
  	 * all further clearing of BLOCK_LOCKS.
  	 *
  	 * FIRST_MOUNT means this node is doing first mounter recovery,
  	 * for which recovery control is handled by
  	 * control_mount()/control_first_done(), not this thread.
  	 */
  	if (!test_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags) ||
  	     test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags)) {
  		spin_unlock(&ls->ls_recover_spin);
  		return;
  	}
  	block_gen = ls->ls_recover_block;
  	start_gen = ls->ls_recover_start;
  	spin_unlock(&ls->ls_recover_spin);
  
  	/*
  	 * Equal block_gen and start_gen implies we are between
  	 * recover_prep and recover_done callbacks, which means
  	 * dlm recovery is in progress and dlm locking is blocked.
  	 * There's no point trying to do any work until recover_done.
  	 */
  
  	if (block_gen == start_gen)
  		return;
  
  	/*
  	 * Propagate recover_submit[] and recover_result[] to lvb:
  	 * dlm_recoverd adds to recover_submit[] jids needing recovery
  	 * gfs2_recover adds to recover_result[] journal recovery results
  	 *
  	 * set lvb bit for jids in recover_submit[] if the lvb has not
  	 * yet been updated for the generation of the failure
  	 *
  	 * clear lvb bit for jids in recover_result[] if the result of
  	 * the journal recovery is SUCCESS
  	 */
  
  	error = control_lock(sdp, DLM_LOCK_EX, DLM_LKF_CONVERT|DLM_LKF_VALBLK);
  	if (error) {
  		fs_err(sdp, "control lock EX error %d
  ", error);
  		return;
  	}
  
  	control_lvb_read(ls, &lvb_gen, ls->ls_lvb_bits);
  
  	spin_lock(&ls->ls_recover_spin);
  	if (block_gen != ls->ls_recover_block ||
  	    start_gen != ls->ls_recover_start) {
  		fs_info(sdp, "recover generation %u block1 %u %u
  ",
  			start_gen, block_gen, ls->ls_recover_block);
  		spin_unlock(&ls->ls_recover_spin);
  		control_lock(sdp, DLM_LOCK_NL, DLM_LKF_CONVERT);
  		return;
  	}
  
  	recover_size = ls->ls_recover_size;
  
  	if (lvb_gen <= start_gen) {
  		/*
  		 * Clear lvb bits for jids we've successfully recovered.
  		 * Because all nodes attempt to recover failed journals,
  		 * a journal can be recovered multiple times successfully
  		 * in succession.  Only the first will really do recovery,
  		 * the others find it clean, but still report a successful
  		 * recovery.  So, another node may have already recovered
  		 * the jid and cleared the lvb bit for it.
  		 */
  		for (i = 0; i < recover_size; i++) {
  			if (ls->ls_recover_result[i] != LM_RD_SUCCESS)
  				continue;
  
  			ls->ls_recover_result[i] = 0;
  
  			if (!test_bit_le(i, ls->ls_lvb_bits + JID_BITMAP_OFFSET))
  				continue;
  
  			__clear_bit_le(i, ls->ls_lvb_bits + JID_BITMAP_OFFSET);
  			write_lvb = 1;
  		}
  	}
  
  	if (lvb_gen == start_gen) {
  		/*
  		 * Failed slots before start_gen are already set in lvb.
  		 */
  		for (i = 0; i < recover_size; i++) {
  			if (!ls->ls_recover_submit[i])
  				continue;
  			if (ls->ls_recover_submit[i] < lvb_gen)
  				ls->ls_recover_submit[i] = 0;
  		}
  	} else if (lvb_gen < start_gen) {
  		/*
  		 * Failed slots before start_gen are not yet set in lvb.
  		 */
  		for (i = 0; i < recover_size; i++) {
  			if (!ls->ls_recover_submit[i])
  				continue;
  			if (ls->ls_recover_submit[i] < start_gen) {
  				ls->ls_recover_submit[i] = 0;
  				__set_bit_le(i, ls->ls_lvb_bits + JID_BITMAP_OFFSET);
  			}
  		}
  		/* even if there are no bits to set, we need to write the
  		   latest generation to the lvb */
  		write_lvb = 1;
  	} else {
  		/*
  		 * we should be getting a recover_done() for lvb_gen soon
  		 */
  	}
  	spin_unlock(&ls->ls_recover_spin);
  
  	if (write_lvb) {
  		control_lvb_write(ls, start_gen, ls->ls_lvb_bits);
  		flags = DLM_LKF_CONVERT | DLM_LKF_VALBLK;
  	} else {
  		flags = DLM_LKF_CONVERT;
  	}
  
  	error = control_lock(sdp, DLM_LOCK_NL, flags);
  	if (error) {
  		fs_err(sdp, "control lock NL error %d
  ", error);
  		return;
  	}
  
  	/*
  	 * Everyone will see jid bits set in the lvb, run gfs2_recover_set(),
  	 * and clear a jid bit in the lvb if the recovery is a success.
  	 * Eventually all journals will be recovered, all jid bits will
  	 * be cleared in the lvb, and everyone will clear BLOCK_LOCKS.
  	 */
  
  	for (i = 0; i < recover_size; i++) {
  		if (test_bit_le(i, ls->ls_lvb_bits + JID_BITMAP_OFFSET)) {
  			fs_info(sdp, "recover generation %u jid %d
  ",
  				start_gen, i);
  			gfs2_recover_set(sdp, i);
  			recover_set++;
  		}
  	}
  	if (recover_set)
  		return;
  
  	/*
  	 * No more jid bits set in lvb, all recovery is done, unblock locks
  	 * (unless a new recover_prep callback has occured blocking locks
  	 * again while working above)
  	 */
  
  	spin_lock(&ls->ls_recover_spin);
  	if (ls->ls_recover_block == block_gen &&
  	    ls->ls_recover_start == start_gen) {
  		clear_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
  		spin_unlock(&ls->ls_recover_spin);
  		fs_info(sdp, "recover generation %u done
  ", start_gen);
  		gfs2_glock_thaw(sdp);
  	} else {
  		fs_info(sdp, "recover generation %u block2 %u %u
  ",
  			start_gen, block_gen, ls->ls_recover_block);
  		spin_unlock(&ls->ls_recover_spin);
  	}
  }
  
  static int control_mount(struct gfs2_sbd *sdp)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	uint32_t start_gen, block_gen, mount_gen, lvb_gen;
  	int mounted_mode;
  	int retries = 0;
  	int error;
  
  	memset(&ls->ls_mounted_lksb, 0, sizeof(struct dlm_lksb));
  	memset(&ls->ls_control_lksb, 0, sizeof(struct dlm_lksb));
  	memset(&ls->ls_control_lvb, 0, GDLM_LVB_SIZE);
  	ls->ls_control_lksb.sb_lvbptr = ls->ls_control_lvb;
  	init_completion(&ls->ls_sync_wait);
  
  	set_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
  
  	error = control_lock(sdp, DLM_LOCK_NL, DLM_LKF_VALBLK);
  	if (error) {
  		fs_err(sdp, "control_mount control_lock NL error %d
  ", error);
  		return error;
  	}
  
  	error = mounted_lock(sdp, DLM_LOCK_NL, 0);
  	if (error) {
  		fs_err(sdp, "control_mount mounted_lock NL error %d
  ", error);
  		control_unlock(sdp);
  		return error;
  	}
  	mounted_mode = DLM_LOCK_NL;
  
  restart:
  	if (retries++ && signal_pending(current)) {
  		error = -EINTR;
  		goto fail;
  	}
  
  	/*
  	 * We always start with both locks in NL. control_lock is
  	 * demoted to NL below so we don't need to do it here.
  	 */
  
  	if (mounted_mode != DLM_LOCK_NL) {
  		error = mounted_lock(sdp, DLM_LOCK_NL, DLM_LKF_CONVERT);
  		if (error)
  			goto fail;
  		mounted_mode = DLM_LOCK_NL;
  	}
  
  	/*
  	 * Other nodes need to do some work in dlm recovery and gfs2_control
  	 * before the recover_done and control_lock will be ready for us below.
  	 * A delay here is not required but often avoids having to retry.
  	 */
  
  	msleep_interruptible(500);
  
  	/*
  	 * Acquire control_lock in EX and mounted_lock in either EX or PR.
  	 * control_lock lvb keeps track of any pending journal recoveries.
  	 * mounted_lock indicates if any other nodes have the fs mounted.
  	 */
  
  	error = control_lock(sdp, DLM_LOCK_EX, DLM_LKF_CONVERT|DLM_LKF_NOQUEUE|DLM_LKF_VALBLK);
  	if (error == -EAGAIN) {
  		goto restart;
  	} else if (error) {
  		fs_err(sdp, "control_mount control_lock EX error %d
  ", error);
  		goto fail;
  	}
  
  	error = mounted_lock(sdp, DLM_LOCK_EX, DLM_LKF_CONVERT|DLM_LKF_NOQUEUE);
  	if (!error) {
  		mounted_mode = DLM_LOCK_EX;
  		goto locks_done;
  	} else if (error != -EAGAIN) {
  		fs_err(sdp, "control_mount mounted_lock EX error %d
  ", error);
  		goto fail;
  	}
  
  	error = mounted_lock(sdp, DLM_LOCK_PR, DLM_LKF_CONVERT|DLM_LKF_NOQUEUE);
  	if (!error) {
  		mounted_mode = DLM_LOCK_PR;
  		goto locks_done;
  	} else {
  		/* not even -EAGAIN should happen here */
  		fs_err(sdp, "control_mount mounted_lock PR error %d
  ", error);
  		goto fail;
  	}
  
  locks_done:
  	/*
  	 * If we got both locks above in EX, then we're the first mounter.
  	 * If not, then we need to wait for the control_lock lvb to be
  	 * updated by other mounted nodes to reflect our mount generation.
  	 *
  	 * In simple first mounter cases, first mounter will see zero lvb_gen,
  	 * but in cases where all existing nodes leave/fail before mounting
  	 * nodes finish control_mount, then all nodes will be mounting and
  	 * lvb_gen will be non-zero.
  	 */
  
  	control_lvb_read(ls, &lvb_gen, ls->ls_lvb_bits);
  
  	if (lvb_gen == 0xFFFFFFFF) {
  		/* special value to force mount attempts to fail */
  		fs_err(sdp, "control_mount control_lock disabled
  ");
  		error = -EINVAL;
  		goto fail;
  	}
  
  	if (mounted_mode == DLM_LOCK_EX) {
  		/* first mounter, keep both EX while doing first recovery */
  		spin_lock(&ls->ls_recover_spin);
  		clear_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
  		set_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags);
  		set_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags);
  		spin_unlock(&ls->ls_recover_spin);
  		fs_info(sdp, "first mounter control generation %u
  ", lvb_gen);
  		return 0;
  	}
  
  	error = control_lock(sdp, DLM_LOCK_NL, DLM_LKF_CONVERT);
  	if (error)
  		goto fail;
  
  	/*
  	 * We are not first mounter, now we need to wait for the control_lock
  	 * lvb generation to be >= the generation from our first recover_done
  	 * and all lvb bits to be clear (no pending journal recoveries.)
  	 */
  
  	if (!all_jid_bits_clear(ls->ls_lvb_bits)) {
  		/* journals need recovery, wait until all are clear */
  		fs_info(sdp, "control_mount wait for journal recovery
  ");
  		goto restart;
  	}
  
  	spin_lock(&ls->ls_recover_spin);
  	block_gen = ls->ls_recover_block;
  	start_gen = ls->ls_recover_start;
  	mount_gen = ls->ls_recover_mount;
  
  	if (lvb_gen < mount_gen) {
  		/* wait for mounted nodes to update control_lock lvb to our
  		   generation, which might include new recovery bits set */
  		fs_info(sdp, "control_mount wait1 block %u start %u mount %u "
  			"lvb %u flags %lx
  ", block_gen, start_gen, mount_gen,
  			lvb_gen, ls->ls_recover_flags);
  		spin_unlock(&ls->ls_recover_spin);
  		goto restart;
  	}
  
  	if (lvb_gen != start_gen) {
  		/* wait for mounted nodes to update control_lock lvb to the
  		   latest recovery generation */
  		fs_info(sdp, "control_mount wait2 block %u start %u mount %u "
  			"lvb %u flags %lx
  ", block_gen, start_gen, mount_gen,
  			lvb_gen, ls->ls_recover_flags);
  		spin_unlock(&ls->ls_recover_spin);
  		goto restart;
  	}
  
  	if (block_gen == start_gen) {
  		/* dlm recovery in progress, wait for it to finish */
  		fs_info(sdp, "control_mount wait3 block %u start %u mount %u "
  			"lvb %u flags %lx
  ", block_gen, start_gen, mount_gen,
  			lvb_gen, ls->ls_recover_flags);
  		spin_unlock(&ls->ls_recover_spin);
  		goto restart;
  	}
  
  	clear_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
  	set_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags);
  	memset(ls->ls_recover_submit, 0, ls->ls_recover_size*sizeof(uint32_t));
  	memset(ls->ls_recover_result, 0, ls->ls_recover_size*sizeof(uint32_t));
  	spin_unlock(&ls->ls_recover_spin);
  	return 0;
  
  fail:
  	mounted_unlock(sdp);
  	control_unlock(sdp);
  	return error;
  }
  
  static int dlm_recovery_wait(void *word)
  {
  	schedule();
  	return 0;
  }
  
  static int control_first_done(struct gfs2_sbd *sdp)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	uint32_t start_gen, block_gen;
  	int error;
  
  restart:
  	spin_lock(&ls->ls_recover_spin);
  	start_gen = ls->ls_recover_start;
  	block_gen = ls->ls_recover_block;
  
  	if (test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags) ||
  	    !test_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags) ||
  	    !test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags)) {
  		/* sanity check, should not happen */
  		fs_err(sdp, "control_first_done start %u block %u flags %lx
  ",
  		       start_gen, block_gen, ls->ls_recover_flags);
  		spin_unlock(&ls->ls_recover_spin);
  		control_unlock(sdp);
  		return -1;
  	}
  
  	if (start_gen == block_gen) {
  		/*
  		 * Wait for the end of a dlm recovery cycle to switch from
  		 * first mounter recovery.  We can ignore any recover_slot
  		 * callbacks between the recover_prep and next recover_done
  		 * because we are still the first mounter and any failed nodes
  		 * have not fully mounted, so they don't need recovery.
  		 */
  		spin_unlock(&ls->ls_recover_spin);
  		fs_info(sdp, "control_first_done wait gen %u
  ", start_gen);
  
  		wait_on_bit(&ls->ls_recover_flags, DFL_DLM_RECOVERY,
  			    dlm_recovery_wait, TASK_UNINTERRUPTIBLE);
  		goto restart;
  	}
  
  	clear_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags);
  	set_bit(DFL_FIRST_MOUNT_DONE, &ls->ls_recover_flags);
  	memset(ls->ls_recover_submit, 0, ls->ls_recover_size*sizeof(uint32_t));
  	memset(ls->ls_recover_result, 0, ls->ls_recover_size*sizeof(uint32_t));
  	spin_unlock(&ls->ls_recover_spin);
  
  	memset(ls->ls_lvb_bits, 0, GDLM_LVB_SIZE);
  	control_lvb_write(ls, start_gen, ls->ls_lvb_bits);
  
  	error = mounted_lock(sdp, DLM_LOCK_PR, DLM_LKF_CONVERT);
  	if (error)
  		fs_err(sdp, "control_first_done mounted PR error %d
  ", error);
  
  	error = control_lock(sdp, DLM_LOCK_NL, DLM_LKF_CONVERT|DLM_LKF_VALBLK);
  	if (error)
  		fs_err(sdp, "control_first_done control NL error %d
  ", error);
  
  	return error;
  }
  
  /*
   * Expand static jid arrays if necessary (by increments of RECOVER_SIZE_INC)
   * to accomodate the largest slot number.  (NB dlm slot numbers start at 1,
   * gfs2 jids start at 0, so jid = slot - 1)
   */
  
  #define RECOVER_SIZE_INC 16
  
  static int set_recover_size(struct gfs2_sbd *sdp, struct dlm_slot *slots,
  			    int num_slots)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	uint32_t *submit = NULL;
  	uint32_t *result = NULL;
  	uint32_t old_size, new_size;
  	int i, max_jid;
  
  	if (!ls->ls_lvb_bits) {
  		ls->ls_lvb_bits = kzalloc(GDLM_LVB_SIZE, GFP_NOFS);
  		if (!ls->ls_lvb_bits)
  			return -ENOMEM;
  	}
  
  	max_jid = 0;
  	for (i = 0; i < num_slots; i++) {
  		if (max_jid < slots[i].slot - 1)
  			max_jid = slots[i].slot - 1;
  	}
  
  	old_size = ls->ls_recover_size;
  
  	if (old_size >= max_jid + 1)
  		return 0;
  
  	new_size = old_size + RECOVER_SIZE_INC;
  
  	submit = kzalloc(new_size * sizeof(uint32_t), GFP_NOFS);
  	result = kzalloc(new_size * sizeof(uint32_t), GFP_NOFS);
  	if (!submit || !result) {
  		kfree(submit);
  		kfree(result);
  		return -ENOMEM;
  	}
  
  	spin_lock(&ls->ls_recover_spin);
  	memcpy(submit, ls->ls_recover_submit, old_size * sizeof(uint32_t));
  	memcpy(result, ls->ls_recover_result, old_size * sizeof(uint32_t));
  	kfree(ls->ls_recover_submit);
  	kfree(ls->ls_recover_result);
  	ls->ls_recover_submit = submit;
  	ls->ls_recover_result = result;
  	ls->ls_recover_size = new_size;
  	spin_unlock(&ls->ls_recover_spin);
  	return 0;
  }
  
  static void free_recover_size(struct lm_lockstruct *ls)
  {
  	kfree(ls->ls_lvb_bits);
  	kfree(ls->ls_recover_submit);
  	kfree(ls->ls_recover_result);
  	ls->ls_recover_submit = NULL;
  	ls->ls_recover_result = NULL;
  	ls->ls_recover_size = 0;
  }
  
  /* dlm calls before it does lock recovery */
  
  static void gdlm_recover_prep(void *arg)
  {
  	struct gfs2_sbd *sdp = arg;
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  
  	spin_lock(&ls->ls_recover_spin);
  	ls->ls_recover_block = ls->ls_recover_start;
  	set_bit(DFL_DLM_RECOVERY, &ls->ls_recover_flags);
  
  	if (!test_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags) ||
  	     test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags)) {
  		spin_unlock(&ls->ls_recover_spin);
  		return;
  	}
  	set_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
  	spin_unlock(&ls->ls_recover_spin);
  }
  
  /* dlm calls after recover_prep has been completed on all lockspace members;
     identifies slot/jid of failed member */
  
  static void gdlm_recover_slot(void *arg, struct dlm_slot *slot)
  {
  	struct gfs2_sbd *sdp = arg;
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	int jid = slot->slot - 1;
  
  	spin_lock(&ls->ls_recover_spin);
  	if (ls->ls_recover_size < jid + 1) {
  		fs_err(sdp, "recover_slot jid %d gen %u short size %d",
  		       jid, ls->ls_recover_block, ls->ls_recover_size);
  		spin_unlock(&ls->ls_recover_spin);
  		return;
  	}
  
  	if (ls->ls_recover_submit[jid]) {
  		fs_info(sdp, "recover_slot jid %d gen %u prev %u",
  			jid, ls->ls_recover_block, ls->ls_recover_submit[jid]);
  	}
  	ls->ls_recover_submit[jid] = ls->ls_recover_block;
  	spin_unlock(&ls->ls_recover_spin);
  }
  
  /* dlm calls after recover_slot and after it completes lock recovery */
  
  static void gdlm_recover_done(void *arg, struct dlm_slot *slots, int num_slots,
  			      int our_slot, uint32_t generation)
  {
  	struct gfs2_sbd *sdp = arg;
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  
  	/* ensure the ls jid arrays are large enough */
  	set_recover_size(sdp, slots, num_slots);
  
  	spin_lock(&ls->ls_recover_spin);
  	ls->ls_recover_start = generation;
  
  	if (!ls->ls_recover_mount) {
  		ls->ls_recover_mount = generation;
  		ls->ls_jid = our_slot - 1;
  	}
  
  	if (!test_bit(DFL_UNMOUNT, &ls->ls_recover_flags))
  		queue_delayed_work(gfs2_control_wq, &sdp->sd_control_work, 0);
  
  	clear_bit(DFL_DLM_RECOVERY, &ls->ls_recover_flags);
  	smp_mb__after_clear_bit();
  	wake_up_bit(&ls->ls_recover_flags, DFL_DLM_RECOVERY);
  	spin_unlock(&ls->ls_recover_spin);
  }
  
  /* gfs2_recover thread has a journal recovery result */
  
  static void gdlm_recovery_result(struct gfs2_sbd *sdp, unsigned int jid,
  				 unsigned int result)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  
  	if (test_bit(DFL_NO_DLM_OPS, &ls->ls_recover_flags))
  		return;
  
  	/* don't care about the recovery of own journal during mount */
  	if (jid == ls->ls_jid)
  		return;
  
  	spin_lock(&ls->ls_recover_spin);
  	if (test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags)) {
  		spin_unlock(&ls->ls_recover_spin);
  		return;
  	}
  	if (ls->ls_recover_size < jid + 1) {
  		fs_err(sdp, "recovery_result jid %d short size %d",
  		       jid, ls->ls_recover_size);
  		spin_unlock(&ls->ls_recover_spin);
  		return;
  	}
  
  	fs_info(sdp, "recover jid %d result %s
  ", jid,
  		result == LM_RD_GAVEUP ? "busy" : "success");
  
  	ls->ls_recover_result[jid] = result;
  
  	/* GAVEUP means another node is recovering the journal; delay our
  	   next attempt to recover it, to give the other node a chance to
  	   finish before trying again */
  
  	if (!test_bit(DFL_UNMOUNT, &ls->ls_recover_flags))
  		queue_delayed_work(gfs2_control_wq, &sdp->sd_control_work,
  				   result == LM_RD_GAVEUP ? HZ : 0);
  	spin_unlock(&ls->ls_recover_spin);
  }
  
  const struct dlm_lockspace_ops gdlm_lockspace_ops = {
  	.recover_prep = gdlm_recover_prep,
  	.recover_slot = gdlm_recover_slot,
  	.recover_done = gdlm_recover_done,
  };
  
  static int gdlm_mount(struct gfs2_sbd *sdp, const char *table)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	char cluster[GFS2_LOCKNAME_LEN];
  	const char *fsname;
  	uint32_t flags;
  	int error, ops_result;
  
  	/*
  	 * initialize everything
  	 */
  
  	INIT_DELAYED_WORK(&sdp->sd_control_work, gfs2_control_func);
  	spin_lock_init(&ls->ls_recover_spin);
  	ls->ls_recover_flags = 0;
  	ls->ls_recover_mount = 0;
  	ls->ls_recover_start = 0;
  	ls->ls_recover_block = 0;
  	ls->ls_recover_size = 0;
  	ls->ls_recover_submit = NULL;
  	ls->ls_recover_result = NULL;
  	ls->ls_lvb_bits = NULL;
  
  	error = set_recover_size(sdp, NULL, 0);
  	if (error)
  		goto fail;
  
  	/*
  	 * prepare dlm_new_lockspace args
  	 */
  
  	fsname = strchr(table, ':');
  	if (!fsname) {
  		fs_info(sdp, "no fsname found
  ");
  		error = -EINVAL;
  		goto fail_free;
  	}
  	memset(cluster, 0, sizeof(cluster));
  	memcpy(cluster, table, strlen(table) - strlen(fsname));
  	fsname++;
  
  	flags = DLM_LSFL_FS | DLM_LSFL_NEWEXCL;
  
  	/*
  	 * create/join lockspace
  	 */
  
  	error = dlm_new_lockspace(fsname, cluster, flags, GDLM_LVB_SIZE,
  				  &gdlm_lockspace_ops, sdp, &ops_result,
  				  &ls->ls_dlm);
  	if (error) {
  		fs_err(sdp, "dlm_new_lockspace error %d
  ", error);
  		goto fail_free;
  	}
  
  	if (ops_result < 0) {
  		/*
  		 * dlm does not support ops callbacks,
  		 * old dlm_controld/gfs_controld are used, try without ops.
  		 */
  		fs_info(sdp, "dlm lockspace ops not used
  ");
  		free_recover_size(ls);
  		set_bit(DFL_NO_DLM_OPS, &ls->ls_recover_flags);
  		return 0;
  	}
  
  	if (!test_bit(SDF_NOJOURNALID, &sdp->sd_flags)) {
  		fs_err(sdp, "dlm lockspace ops disallow jid preset
  ");
  		error = -EINVAL;
  		goto fail_release;
  	}
  
  	/*
  	 * control_mount() uses control_lock to determine first mounter,
  	 * and for later mounts, waits for any recoveries to be cleared.
  	 */
  
  	error = control_mount(sdp);
  	if (error) {
  		fs_err(sdp, "mount control error %d
  ", error);
  		goto fail_release;
  	}
  
  	ls->ls_first = !!test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags);
  	clear_bit(SDF_NOJOURNALID, &sdp->sd_flags);
  	smp_mb__after_clear_bit();
  	wake_up_bit(&sdp->sd_flags, SDF_NOJOURNALID);
  	return 0;
  
  fail_release:
  	dlm_release_lockspace(ls->ls_dlm, 2);
  fail_free:
  	free_recover_size(ls);
  fail:
  	return error;
  }
  
  static void gdlm_first_done(struct gfs2_sbd *sdp)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  	int error;
  
  	if (test_bit(DFL_NO_DLM_OPS, &ls->ls_recover_flags))
  		return;
  
  	error = control_first_done(sdp);
  	if (error)
  		fs_err(sdp, "mount first_done error %d
  ", error);
  }
  
  static void gdlm_unmount(struct gfs2_sbd *sdp)
  {
  	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
  
  	if (test_bit(DFL_NO_DLM_OPS, &ls->ls_recover_flags))
  		goto release;
  
  	/* wait for gfs2_control_wq to be done with this mount */
  
  	spin_lock(&ls->ls_recover_spin);
  	set_bit(DFL_UNMOUNT, &ls->ls_recover_flags);
  	spin_unlock(&ls->ls_recover_spin);
  	flush_delayed_work(&sdp->sd_control_work);
  
  	/* mounted_lock and control_lock will be purged in dlm recovery */
  release:
  	if (ls->ls_dlm) {
  		dlm_release_lockspace(ls->ls_dlm, 2);
  		ls->ls_dlm = NULL;
  	}
  
  	free_recover_size(ls);
  }
  
  static const match_table_t dlm_tokens = {
  	{ Opt_jid, "jid=%d"},
  	{ Opt_id, "id=%d"},
  	{ Opt_first, "first=%d"},
  	{ Opt_nodir, "nodir=%d"},
  	{ Opt_err, NULL },
  };
  
  const struct lm_lockops gfs2_dlm_ops = {
  	.lm_proto_name = "lock_dlm",
  	.lm_mount = gdlm_mount,
  	.lm_first_done = gdlm_first_done,
  	.lm_recovery_result = gdlm_recovery_result,
  	.lm_unmount = gdlm_unmount,
  	.lm_put_lock = gdlm_put_lock,
  	.lm_lock = gdlm_lock,
  	.lm_cancel = gdlm_cancel,
  	.lm_tokens = &dlm_tokens,
  };