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 000000000000..a0bb7d2251a0
--- /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,
+};
+