GFS2: Merge lock_dlm module into GFS2

This is the big patch that I've been working on for some time
now. There are many reasons for wanting to make this change
such as:
 o Reducing overhead by eliminating duplicated fields between structures
 o Simplifcation of the code (reduces the code size by a fair bit)
 o The locking interface is now the DLM interface itself as proposed
   some time ago.
 o Fewer lookups of glocks when processing replies from the DLM
 o Fewer memory allocations/deallocations for each glock
 o Scope to do further optimisations in the future (but this patch is
   more than big enough for now!)

Please note that (a) this patch relates to the lock_dlm module and
not the DLM itself, that is still a separate module; and (b) that
we retain the ability to build GFS2 as a standalone single node
filesystem with out requiring the DLM.

This patch needs a lot of testing, hence my keeping it I restarted
my -git tree after the last merge window. That way, this has the maximum
exposure before its merged. This is (modulo a few minor bug fixes) the
same patch that I've been posting on and off the the last three months
and its passed a number of different tests so far.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 240 insertions, 0 deletions

diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c
new file mode 100644
index 00000000000..a0bb7d2251a
--- /dev/null
+++ b/fs/gfs2/lock_dlm.c
@@ -0,0 +1,240 @@
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2009 Red Hat, Inc.  All rights reserved.
+ *
+ * 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/types.h>
+#include <linux/gfs2_ondisk.h>
+
+#include "incore.h"
+#include "glock.h"
+#include "util.h"
+
+
+static void gdlm_ast(void *arg)
+{
+	struct gfs2_glock *gl = arg;
+	unsigned ret = gl->gl_state;
+
+	BUG_ON(gl->gl_lksb.sb_flags & DLM_SBF_DEMOTED);
+
+	if (gl->gl_lksb.sb_flags & DLM_SBF_VALNOTVALID)
+		memset(gl->gl_lvb, 0, GDLM_LVB_SIZE);
+
+	switch (gl->gl_lksb.sb_status) {
+	case -DLM_EUNLOCK: /* Unlocked, so glock can be freed */
+		kmem_cache_free(gfs2_glock_cachep, gl);
+		return;
+	case -DLM_ECANCEL: /* Cancel while getting lock */
+		ret |= LM_OUT_CANCELED;
+		goto out;
+	case -EAGAIN: /* Try lock fails */
+		goto out;
+	case -EINVAL: /* Invalid */
+	case -ENOMEM: /* Out of memory */
+		ret |= LM_OUT_ERROR;
+		goto out;
+	case 0: /* Success */
+		break;
+	default: /* Something unexpected */
+		BUG();
+	}
+
+	ret = gl->gl_target;
+	if (gl->gl_lksb.sb_flags & DLM_SBF_ALTMODE) {
+		if (gl->gl_target == LM_ST_SHARED)
+			ret = LM_ST_DEFERRED;
+		else if (gl->gl_target == 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(const u32 lkid, const unsigned int gfs_flags,
+		      const int req)
+{
+	u32 lkf = 0;
+
+	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 (lkid != 0) 
+		lkf |= DLM_LKF_CONVERT;
+
+	lkf |= DLM_LKF_VALBLK;
+
+	return lkf;
+}
+
+static unsigned int gdlm_lock(struct gfs2_glock *gl,
+			      unsigned int req_state, unsigned int flags)
+{
+	struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
+	int error;
+	int req;
+	u32 lkf;
+
+	req = make_mode(req_state);
+	lkf = make_flags(gl->gl_lksb.sb_lkid, flags, req);
+
+	/*
+	 * Submit the actual lock request.
+	 */
+
+	error = dlm_lock(ls->ls_dlm, req, &gl->gl_lksb, lkf, gl->gl_strname,
+			 GDLM_STRNAME_BYTES - 1, 0, gdlm_ast, gl, gdlm_bast);
+	if (error == -EAGAIN)
+		return 0;
+	if (error)
+		return LM_OUT_ERROR;
+	return LM_OUT_ASYNC;
+}
+
+static void gdlm_put_lock(struct kmem_cache *cachep, void *ptr)
+{
+	struct gfs2_glock *gl = ptr;
+	struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
+	int error;
+
+	if (gl->gl_lksb.sb_lkid == 0) {
+		kmem_cache_free(cachep, 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\n",
+		       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);
+}
+
+static int gdlm_mount(struct gfs2_sbd *sdp, const char *fsname)
+{
+	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
+	int error;
+
+	if (fsname == NULL) {
+		fs_info(sdp, "no fsname found\n");
+		return -EINVAL;
+	}
+
+	error = dlm_new_lockspace(fsname, strlen(fsname), &ls->ls_dlm,
+				  DLM_LSFL_FS | DLM_LSFL_NEWEXCL |
+				  (ls->ls_nodir ? DLM_LSFL_NODIR : 0),
+				  GDLM_LVB_SIZE);
+	if (error)
+		printk(KERN_ERR "dlm_new_lockspace error %d", error);
+
+	return error;
+}
+
+static void gdlm_unmount(struct gfs2_sbd *sdp)
+{
+	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
+
+	if (ls->ls_dlm) {
+		dlm_release_lockspace(ls->ls_dlm, 2);
+		ls->ls_dlm = NULL;
+	}
+}
+
+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_unmount = gdlm_unmount,
+	.lm_put_lock = gdlm_put_lock,
+	.lm_lock = gdlm_lock,
+	.lm_cancel = gdlm_cancel,
+	.lm_tokens = &dlm_tokens,
+};
+