[GFS2] No lock_nolock

This patch merges the lock_nolock module into GFS2 itself. As well as removing
some of the overhead of the module, it also means that its now impossible to
build GFS2 without a lock module (which would be a pointless thing to do
anyway).

We also plan to merge lock_dlm into GFS2 in the future, but that is a more
tricky task, and will therefore be a separate patch.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: David Teigland <teigland@redhat.com>

fs/gfs2/Kconfig

@@ -14,23 +14,11 @@ config GFS2_FS
 	  GFS is perfect consistency -- changes made to the filesystem on one
 	  machine show up immediately on all other machines in the cluster.
 
-	  To use the GFS2 filesystem, you will need to enable one or more of
-	  the below locking modules. Documentation and utilities for GFS2 can
+	  To use the GFS2 filesystem in a cluster, you will need to enable
+	  the locking module below. Documentation and utilities for GFS2 can
 	  be found here: http://sources.redhat.com/cluster
 
-config GFS2_FS_LOCKING_NOLOCK
-	tristate "GFS2 \"nolock\" locking module"
-	depends on GFS2_FS
-	help
-	  Single node locking module for GFS2.
-
-	  Use this module if you want to use GFS2 on a single node without
-	  its clustering features. You can still take advantage of the
-	  large file support, and upgrade to running a full cluster later on
-	  if required.
-
-	  If you will only be using GFS2 in cluster mode, you do not need this
-	  module.
+	  The "nolock" lock module is now built in to GFS2 by default.
 
 config GFS2_FS_LOCKING_DLM
 	tristate "GFS2 DLM locking module"

fs/gfs2/Makefile

@@ -5,6 +5,5 @@ gfs2-y := acl.o bmap.o daemon.o dir.o eaops.o eattr.o glock.o \
 	ops_fstype.o ops_inode.o ops_super.o quota.o \
 	recovery.o rgrp.o super.o sys.o trans.o util.o
 
-obj-$(CONFIG_GFS2_FS_LOCKING_NOLOCK) += locking/nolock/
 obj-$(CONFIG_GFS2_FS_LOCKING_DLM) += locking/dlm/
 

fs/gfs2/glock.c

@@ -153,7 +153,7 @@ static void glock_free(struct gfs2_glock *gl)
 	struct gfs2_sbd *sdp = gl->gl_sbd;
 	struct inode *aspace = gl->gl_aspace;
 
-	if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+	if (sdp->sd_lockstruct.ls_ops->lm_put_lock)
 		sdp->sd_lockstruct.ls_ops->lm_put_lock(gl->gl_lock);
 
 	if (aspace)
@@ -488,6 +488,10 @@ static unsigned int gfs2_lm_lock(struct gfs2_sbd *sdp, void *lock,
 				 unsigned int flags)
 {
 	int ret = LM_OUT_ERROR;
+
+	if (!sdp->sd_lockstruct.ls_ops->lm_lock)
+		return req_state == LM_ST_UNLOCKED ? 0 : req_state;
+
 	if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 		ret = sdp->sd_lockstruct.ls_ops->lm_lock(lock, cur_state,
 							 req_state, flags);
@@ -631,6 +635,8 @@ static int gfs2_lm_get_lock(struct gfs2_sbd *sdp, struct lm_lockname *name,
 		     void **lockp)
 {
 	int error = -EIO;
+	if (!sdp->sd_lockstruct.ls_ops->lm_get_lock)
+		return 0;
 	if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 		error = sdp->sd_lockstruct.ls_ops->lm_get_lock(
 				sdp->sd_lockstruct.ls_lockspace, name, lockp);
@@ -910,7 +916,8 @@ static inline void add_to_queue(struct gfs2_holder *gh)
 	gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 	if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
 		spin_unlock(&gl->gl_spin);
-		sdp->sd_lockstruct.ls_ops->lm_cancel(gl->gl_lock);
+		if (sdp->sd_lockstruct.ls_ops->lm_cancel)
+			sdp->sd_lockstruct.ls_ops->lm_cancel(gl->gl_lock);
 		spin_lock(&gl->gl_spin);
 	}
 	return;
@@ -1187,6 +1194,8 @@ void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
 static int gfs2_lm_hold_lvb(struct gfs2_sbd *sdp, void *lock, char **lvbp)
 {
 	int error = -EIO;
+	if (!sdp->sd_lockstruct.ls_ops->lm_hold_lvb)
+		return 0;
 	if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 		error = sdp->sd_lockstruct.ls_ops->lm_hold_lvb(lock, lvbp);
 	return error;
@@ -1226,7 +1235,7 @@ void gfs2_lvb_unhold(struct gfs2_glock *gl)
 	gfs2_glock_hold(gl);
 	gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
 	if (atomic_dec_and_test(&gl->gl_lvb_count)) {
-		if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+		if (sdp->sd_lockstruct.ls_ops->lm_unhold_lvb)
 			sdp->sd_lockstruct.ls_ops->lm_unhold_lvb(gl->gl_lock, gl->gl_lvb);
 		gl->gl_lvb = NULL;
 		gfs2_glock_put(gl);

fs/gfs2/locking.c

@@ -23,12 +23,54 @@ struct lmh_wrapper {
 	const struct lm_lockops *lw_ops;
 };
 
+static int nolock_mount(char *table_name, char *host_data,
+			lm_callback_t cb, void *cb_data,
+			unsigned int min_lvb_size, int flags,
+			struct lm_lockstruct *lockstruct,
+			struct kobject *fskobj);
+
 /* List of registered low-level locking protocols.  A file system selects one
    of them by name at mount time, e.g. lock_nolock, lock_dlm. */
 
+static const struct lm_lockops nolock_ops = {
+	.lm_proto_name = "lock_nolock",
+	.lm_mount = nolock_mount,
+};
+
+static struct lmh_wrapper nolock_proto  = {
+	.lw_list = LIST_HEAD_INIT(nolock_proto.lw_list),
+	.lw_ops = &nolock_ops,
+};
+
 static LIST_HEAD(lmh_list);
 static DEFINE_MUTEX(lmh_lock);
 
+static int nolock_mount(char *table_name, char *host_data,
+			lm_callback_t cb, void *cb_data,
+			unsigned int min_lvb_size, int flags,
+			struct lm_lockstruct *lockstruct,
+			struct kobject *fskobj)
+{
+	char *c;
+	unsigned int jid;
+
+	c = strstr(host_data, "jid=");
+	if (!c)
+		jid = 0;
+	else {
+		c += 4;
+		sscanf(c, "%u", &jid);
+	}
+
+	lockstruct->ls_jid = jid;
+	lockstruct->ls_first = 1;
+	lockstruct->ls_lvb_size = min_lvb_size;
+	lockstruct->ls_ops = &nolock_ops;
+	lockstruct->ls_flags = LM_LSFLAG_LOCAL;
+
+	return 0;
+}
+
 /**
  * gfs2_register_lockproto - Register a low-level locking protocol
  * @proto: the protocol definition
@@ -116,9 +158,13 @@ int gfs2_mount_lockproto(char *proto_name, char *table_name, char *host_data,
 	int try = 0;
 	int error, found;
 
+
 retry:
 	mutex_lock(&lmh_lock);
 
+	if (list_empty(&nolock_proto.lw_list))
+		list_add(&lmh_list, &nolock_proto.lw_list);
+
 	found = 0;
 	list_for_each_entry(lw, &lmh_list, lw_list) {
 		if (!strcmp(lw->lw_ops->lm_proto_name, proto_name)) {
@@ -139,7 +185,8 @@ int gfs2_mount_lockproto(char *proto_name, char *table_name, char *host_data,
 		goto out;
 	}
 
-	if (!try_module_get(lw->lw_ops->lm_owner)) {
+	if (lw->lw_ops->lm_owner &&
+	    !try_module_get(lw->lw_ops->lm_owner)) {
 		try = 0;
 		mutex_unlock(&lmh_lock);
 		msleep(1000);
@@ -158,7 +205,8 @@ int gfs2_mount_lockproto(char *proto_name, char *table_name, char *host_data,
 void gfs2_unmount_lockproto(struct lm_lockstruct *lockstruct)
 {
 	mutex_lock(&lmh_lock);
-	lockstruct->ls_ops->lm_unmount(lockstruct->ls_lockspace);
+	if (lockstruct->ls_ops->lm_unmount)
+		lockstruct->ls_ops->lm_unmount(lockstruct->ls_lockspace);
 	if (lockstruct->ls_ops->lm_owner)
 		module_put(lockstruct->ls_ops->lm_owner);
 	mutex_unlock(&lmh_lock);