[PATCH] OCFS2: The Second Oracle Cluster Filesystem
dlmfs: A minimal dlm userspace interface implemented via a virtual
file system.
Most of the OCFS2 tools make use of this to take cluster locks when
doing operations on the file system.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>
diff --git a/fs/ocfs2/dlm/userdlm.c b/fs/ocfs2/dlm/userdlm.c
new file mode 100644
index 0000000..e1fdd28
--- /dev/null
+++ b/fs/ocfs2/dlm/userdlm.c
@@ -0,0 +1,658 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * userdlm.c
+ *
+ * Code which implements the kernel side of a minimal userspace
+ * interface to our DLM.
+ *
+ * Many of the functions here are pared down versions of dlmglue.c
+ * functions.
+ *
+ * Copyright (C) 2003, 2004 Oracle. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <asm/signal.h>
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/crc32.h>
+
+
+#include "cluster/nodemanager.h"
+#include "cluster/heartbeat.h"
+#include "cluster/tcp.h"
+
+#include "dlmapi.h"
+
+#include "userdlm.h"
+
+#define MLOG_MASK_PREFIX ML_DLMFS
+#include "cluster/masklog.h"
+
+static inline int user_check_wait_flag(struct user_lock_res *lockres,
+ int flag)
+{
+ int ret;
+
+ spin_lock(&lockres->l_lock);
+ ret = lockres->l_flags & flag;
+ spin_unlock(&lockres->l_lock);
+
+ return ret;
+}
+
+static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)
+
+{
+ wait_event(lockres->l_event,
+ !user_check_wait_flag(lockres, USER_LOCK_BUSY));
+}
+
+static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)
+
+{
+ wait_event(lockres->l_event,
+ !user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
+}
+
+/* I heart container_of... */
+static inline struct dlm_ctxt *
+dlm_ctxt_from_user_lockres(struct user_lock_res *lockres)
+{
+ struct dlmfs_inode_private *ip;
+
+ ip = container_of(lockres,
+ struct dlmfs_inode_private,
+ ip_lockres);
+ return ip->ip_dlm;
+}
+
+static struct inode *
+user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
+{
+ struct dlmfs_inode_private *ip;
+
+ ip = container_of(lockres,
+ struct dlmfs_inode_private,
+ ip_lockres);
+ return &ip->ip_vfs_inode;
+}
+
+static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
+{
+ spin_lock(&lockres->l_lock);
+ lockres->l_flags &= ~USER_LOCK_BUSY;
+ spin_unlock(&lockres->l_lock);
+}
+
+#define user_log_dlm_error(_func, _stat, _lockres) do { \
+ mlog(ML_ERROR, "Dlm error \"%s\" while calling %s on " \
+ "resource %s: %s\n", dlm_errname(_stat), _func, \
+ _lockres->l_name, dlm_errmsg(_stat)); \
+} while (0)
+
+/* WARNING: This function lives in a world where the only three lock
+ * levels are EX, PR, and NL. It *will* have to be adjusted when more
+ * lock types are added. */
+static inline int user_highest_compat_lock_level(int level)
+{
+ int new_level = LKM_EXMODE;
+
+ if (level == LKM_EXMODE)
+ new_level = LKM_NLMODE;
+ else if (level == LKM_PRMODE)
+ new_level = LKM_PRMODE;
+ return new_level;
+}
+
+static void user_ast(void *opaque)
+{
+ struct user_lock_res *lockres = opaque;
+ struct dlm_lockstatus *lksb;
+
+ mlog(0, "AST fired for lockres %s\n", lockres->l_name);
+
+ spin_lock(&lockres->l_lock);
+
+ lksb = &(lockres->l_lksb);
+ if (lksb->status != DLM_NORMAL) {
+ mlog(ML_ERROR, "lksb status value of %u on lockres %s\n",
+ lksb->status, lockres->l_name);
+ spin_unlock(&lockres->l_lock);
+ return;
+ }
+
+ /* we're downconverting. */
+ if (lockres->l_requested < lockres->l_level) {
+ if (lockres->l_requested <=
+ user_highest_compat_lock_level(lockres->l_blocking)) {
+ lockres->l_blocking = LKM_NLMODE;
+ lockres->l_flags &= ~USER_LOCK_BLOCKED;
+ }
+ }
+
+ lockres->l_level = lockres->l_requested;
+ lockres->l_requested = LKM_IVMODE;
+ lockres->l_flags |= USER_LOCK_ATTACHED;
+ lockres->l_flags &= ~USER_LOCK_BUSY;
+
+ spin_unlock(&lockres->l_lock);
+
+ wake_up(&lockres->l_event);
+}
+
+static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
+{
+ struct inode *inode;
+ inode = user_dlm_inode_from_user_lockres(lockres);
+ if (!igrab(inode))
+ BUG();
+}
+
+static void user_dlm_unblock_lock(void *opaque);
+
+static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
+{
+ if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
+ user_dlm_grab_inode_ref(lockres);
+
+ INIT_WORK(&lockres->l_work, user_dlm_unblock_lock,
+ lockres);
+
+ queue_work(user_dlm_worker, &lockres->l_work);
+ lockres->l_flags |= USER_LOCK_QUEUED;
+ }
+}
+
+static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
+{
+ int queue = 0;
+
+ if (!(lockres->l_flags & USER_LOCK_BLOCKED))
+ return;
+
+ switch (lockres->l_blocking) {
+ case LKM_EXMODE:
+ if (!lockres->l_ex_holders && !lockres->l_ro_holders)
+ queue = 1;
+ break;
+ case LKM_PRMODE:
+ if (!lockres->l_ex_holders)
+ queue = 1;
+ break;
+ default:
+ BUG();
+ }
+
+ if (queue)
+ __user_dlm_queue_lockres(lockres);
+}
+
+static void user_bast(void *opaque, int level)
+{
+ struct user_lock_res *lockres = opaque;
+
+ mlog(0, "Blocking AST fired for lockres %s. Blocking level %d\n",
+ lockres->l_name, level);
+
+ spin_lock(&lockres->l_lock);
+ lockres->l_flags |= USER_LOCK_BLOCKED;
+ if (level > lockres->l_blocking)
+ lockres->l_blocking = level;
+
+ __user_dlm_queue_lockres(lockres);
+ spin_unlock(&lockres->l_lock);
+
+ wake_up(&lockres->l_event);
+}
+
+static void user_unlock_ast(void *opaque, enum dlm_status status)
+{
+ struct user_lock_res *lockres = opaque;
+
+ mlog(0, "UNLOCK AST called on lock %s\n", lockres->l_name);
+
+ if (status != DLM_NORMAL)
+ mlog(ML_ERROR, "Dlm returns status %d\n", status);
+
+ spin_lock(&lockres->l_lock);
+ if (lockres->l_flags & USER_LOCK_IN_TEARDOWN)
+ lockres->l_level = LKM_IVMODE;
+ else {
+ lockres->l_requested = LKM_IVMODE; /* cancel an
+ * upconvert
+ * request. */
+ lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
+ /* we want the unblock thread to look at it again
+ * now. */
+ __user_dlm_queue_lockres(lockres);
+ }
+
+ lockres->l_flags &= ~USER_LOCK_BUSY;
+ spin_unlock(&lockres->l_lock);
+
+ wake_up(&lockres->l_event);
+}
+
+static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
+{
+ struct inode *inode;
+ inode = user_dlm_inode_from_user_lockres(lockres);
+ iput(inode);
+}
+
+static void user_dlm_unblock_lock(void *opaque)
+{
+ int new_level, status;
+ struct user_lock_res *lockres = (struct user_lock_res *) opaque;
+ struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
+
+ mlog(0, "processing lockres %s\n", lockres->l_name);
+
+ spin_lock(&lockres->l_lock);
+
+ BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
+ BUG_ON(!(lockres->l_flags & USER_LOCK_QUEUED));
+
+ /* notice that we don't clear USER_LOCK_BLOCKED here. That's
+ * for user_ast to do. */
+ lockres->l_flags &= ~USER_LOCK_QUEUED;
+
+ if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
+ mlog(0, "lock is in teardown so we do nothing\n");
+ spin_unlock(&lockres->l_lock);
+ goto drop_ref;
+ }
+
+ if (lockres->l_flags & USER_LOCK_BUSY) {
+ mlog(0, "BUSY flag detected...\n");
+ if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
+ spin_unlock(&lockres->l_lock);
+ goto drop_ref;
+ }
+
+ lockres->l_flags |= USER_LOCK_IN_CANCEL;
+ spin_unlock(&lockres->l_lock);
+
+ status = dlmunlock(dlm,
+ &lockres->l_lksb,
+ LKM_CANCEL,
+ user_unlock_ast,
+ lockres);
+ if (status == DLM_CANCELGRANT) {
+ /* If we got this, then the ast was fired
+ * before we could cancel. We cleanup our
+ * state, and restart the function. */
+ spin_lock(&lockres->l_lock);
+ lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
+ spin_unlock(&lockres->l_lock);
+ } else if (status != DLM_NORMAL)
+ user_log_dlm_error("dlmunlock", status, lockres);
+ goto drop_ref;
+ }
+
+ /* If there are still incompat holders, we can exit safely
+ * without worrying about re-queueing this lock as that will
+ * happen on the last call to user_cluster_unlock. */
+ if ((lockres->l_blocking == LKM_EXMODE)
+ && (lockres->l_ex_holders || lockres->l_ro_holders)) {
+ spin_unlock(&lockres->l_lock);
+ mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
+ lockres->l_ro_holders, lockres->l_ex_holders);
+ goto drop_ref;
+ }
+
+ if ((lockres->l_blocking == LKM_PRMODE)
+ && lockres->l_ex_holders) {
+ spin_unlock(&lockres->l_lock);
+ mlog(0, "can't downconvert for pr: ex = %u\n",
+ lockres->l_ex_holders);
+ goto drop_ref;
+ }
+
+ /* yay, we can downconvert now. */
+ new_level = user_highest_compat_lock_level(lockres->l_blocking);
+ lockres->l_requested = new_level;
+ lockres->l_flags |= USER_LOCK_BUSY;
+ mlog(0, "Downconvert lock from %d to %d\n",
+ lockres->l_level, new_level);
+ spin_unlock(&lockres->l_lock);
+
+ /* need lock downconvert request now... */
+ status = dlmlock(dlm,
+ new_level,
+ &lockres->l_lksb,
+ LKM_CONVERT|LKM_VALBLK,
+ lockres->l_name,
+ user_ast,
+ lockres,
+ user_bast);
+ if (status != DLM_NORMAL) {
+ user_log_dlm_error("dlmlock", status, lockres);
+ user_recover_from_dlm_error(lockres);
+ }
+
+drop_ref:
+ user_dlm_drop_inode_ref(lockres);
+}
+
+static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
+ int level)
+{
+ switch(level) {
+ case LKM_EXMODE:
+ lockres->l_ex_holders++;
+ break;
+ case LKM_PRMODE:
+ lockres->l_ro_holders++;
+ break;
+ default:
+ BUG();
+ }
+}
+
+/* predict what lock level we'll be dropping down to on behalf
+ * of another node, and return true if the currently wanted
+ * level will be compatible with it. */
+static inline int
+user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
+ int wanted)
+{
+ BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
+
+ return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
+}
+
+int user_dlm_cluster_lock(struct user_lock_res *lockres,
+ int level,
+ int lkm_flags)
+{
+ int status, local_flags;
+ struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
+
+ if (level != LKM_EXMODE &&
+ level != LKM_PRMODE) {
+ mlog(ML_ERROR, "lockres %s: invalid request!\n",
+ lockres->l_name);
+ status = -EINVAL;
+ goto bail;
+ }
+
+ mlog(0, "lockres %s: asking for %s lock, passed flags = 0x%x\n",
+ lockres->l_name,
+ (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
+ lkm_flags);
+
+again:
+ if (signal_pending(current)) {
+ status = -ERESTARTSYS;
+ goto bail;
+ }
+
+ spin_lock(&lockres->l_lock);
+
+ /* We only compare against the currently granted level
+ * here. If the lock is blocked waiting on a downconvert,
+ * we'll get caught below. */
+ if ((lockres->l_flags & USER_LOCK_BUSY) &&
+ (level > lockres->l_level)) {
+ /* is someone sitting in dlm_lock? If so, wait on
+ * them. */
+ spin_unlock(&lockres->l_lock);
+
+ user_wait_on_busy_lock(lockres);
+ goto again;
+ }
+
+ if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
+ (!user_may_continue_on_blocked_lock(lockres, level))) {
+ /* is the lock is currently blocked on behalf of
+ * another node */
+ spin_unlock(&lockres->l_lock);
+
+ user_wait_on_blocked_lock(lockres);
+ goto again;
+ }
+
+ if (level > lockres->l_level) {
+ local_flags = lkm_flags | LKM_VALBLK;
+ if (lockres->l_level != LKM_IVMODE)
+ local_flags |= LKM_CONVERT;
+
+ lockres->l_requested = level;
+ lockres->l_flags |= USER_LOCK_BUSY;
+ spin_unlock(&lockres->l_lock);
+
+ BUG_ON(level == LKM_IVMODE);
+ BUG_ON(level == LKM_NLMODE);
+
+ mlog(0, "lock %s, get lock from %d to level = %d\n",
+ lockres->l_name, lockres->l_level, level);
+
+ /* call dlm_lock to upgrade lock now */
+ status = dlmlock(dlm,
+ level,
+ &lockres->l_lksb,
+ local_flags,
+ lockres->l_name,
+ user_ast,
+ lockres,
+ user_bast);
+ if (status != DLM_NORMAL) {
+ if ((lkm_flags & LKM_NOQUEUE) &&
+ (status == DLM_NOTQUEUED))
+ status = -EAGAIN;
+ else {
+ user_log_dlm_error("dlmlock", status, lockres);
+ status = -EINVAL;
+ }
+ user_recover_from_dlm_error(lockres);
+ goto bail;
+ }
+
+ mlog(0, "lock %s, successfull return from dlmlock\n",
+ lockres->l_name);
+
+ user_wait_on_busy_lock(lockres);
+ goto again;
+ }
+
+ user_dlm_inc_holders(lockres, level);
+ spin_unlock(&lockres->l_lock);
+
+ mlog(0, "lockres %s: Got %s lock!\n", lockres->l_name,
+ (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
+
+ status = 0;
+bail:
+ return status;
+}
+
+static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
+ int level)
+{
+ switch(level) {
+ case LKM_EXMODE:
+ BUG_ON(!lockres->l_ex_holders);
+ lockres->l_ex_holders--;
+ break;
+ case LKM_PRMODE:
+ BUG_ON(!lockres->l_ro_holders);
+ lockres->l_ro_holders--;
+ break;
+ default:
+ BUG();
+ }
+}
+
+void user_dlm_cluster_unlock(struct user_lock_res *lockres,
+ int level)
+{
+ if (level != LKM_EXMODE &&
+ level != LKM_PRMODE) {
+ mlog(ML_ERROR, "lockres %s: invalid request!\n", lockres->l_name);
+ return;
+ }
+
+ mlog(0, "lockres %s: dropping %s lock\n", lockres->l_name,
+ (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
+
+ spin_lock(&lockres->l_lock);
+ user_dlm_dec_holders(lockres, level);
+ __user_dlm_cond_queue_lockres(lockres);
+ spin_unlock(&lockres->l_lock);
+}
+
+void user_dlm_write_lvb(struct inode *inode,
+ const char *val,
+ unsigned int len)
+{
+ struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
+ char *lvb = lockres->l_lksb.lvb;
+
+ BUG_ON(len > DLM_LVB_LEN);
+
+ spin_lock(&lockres->l_lock);
+
+ BUG_ON(lockres->l_level < LKM_EXMODE);
+ memcpy(lvb, val, len);
+
+ spin_unlock(&lockres->l_lock);
+}
+
+void user_dlm_read_lvb(struct inode *inode,
+ char *val,
+ unsigned int len)
+{
+ struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
+ char *lvb = lockres->l_lksb.lvb;
+
+ BUG_ON(len > DLM_LVB_LEN);
+
+ spin_lock(&lockres->l_lock);
+
+ BUG_ON(lockres->l_level < LKM_PRMODE);
+ memcpy(val, lvb, len);
+
+ spin_unlock(&lockres->l_lock);
+}
+
+void user_dlm_lock_res_init(struct user_lock_res *lockres,
+ struct dentry *dentry)
+{
+ memset(lockres, 0, sizeof(*lockres));
+
+ spin_lock_init(&lockres->l_lock);
+ init_waitqueue_head(&lockres->l_event);
+ lockres->l_level = LKM_IVMODE;
+ lockres->l_requested = LKM_IVMODE;
+ lockres->l_blocking = LKM_IVMODE;
+
+ /* should have been checked before getting here. */
+ BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
+
+ memcpy(lockres->l_name,
+ dentry->d_name.name,
+ dentry->d_name.len);
+}
+
+int user_dlm_destroy_lock(struct user_lock_res *lockres)
+{
+ int status = -EBUSY;
+ struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
+
+ mlog(0, "asked to destroy %s\n", lockres->l_name);
+
+ spin_lock(&lockres->l_lock);
+ while (lockres->l_flags & USER_LOCK_BUSY) {
+ spin_unlock(&lockres->l_lock);
+
+ mlog(0, "lock %s is busy\n", lockres->l_name);
+
+ user_wait_on_busy_lock(lockres);
+
+ spin_lock(&lockres->l_lock);
+ }
+
+ if (lockres->l_ro_holders || lockres->l_ex_holders) {
+ spin_unlock(&lockres->l_lock);
+ mlog(0, "lock %s has holders\n", lockres->l_name);
+ goto bail;
+ }
+
+ status = 0;
+ if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
+ spin_unlock(&lockres->l_lock);
+ mlog(0, "lock %s is not attached\n", lockres->l_name);
+ goto bail;
+ }
+
+ lockres->l_flags &= ~USER_LOCK_ATTACHED;
+ lockres->l_flags |= USER_LOCK_BUSY;
+ lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
+ spin_unlock(&lockres->l_lock);
+
+ mlog(0, "unlocking lockres %s\n", lockres->l_name);
+ status = dlmunlock(dlm,
+ &lockres->l_lksb,
+ LKM_VALBLK,
+ user_unlock_ast,
+ lockres);
+ if (status != DLM_NORMAL) {
+ user_log_dlm_error("dlmunlock", status, lockres);
+ status = -EINVAL;
+ goto bail;
+ }
+
+ user_wait_on_busy_lock(lockres);
+
+ status = 0;
+bail:
+ return status;
+}
+
+struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
+{
+ struct dlm_ctxt *dlm;
+ u32 dlm_key;
+ char *domain;
+
+ domain = kmalloc(name->len + 1, GFP_KERNEL);
+ if (!domain) {
+ mlog_errno(-ENOMEM);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ dlm_key = crc32_le(0, name->name, name->len);
+
+ snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
+
+ dlm = dlm_register_domain(domain, dlm_key);
+ if (IS_ERR(dlm))
+ mlog_errno(PTR_ERR(dlm));
+
+ kfree(domain);
+ return dlm;
+}
+
+void user_dlm_unregister_context(struct dlm_ctxt *dlm)
+{
+ dlm_unregister_domain(dlm);
+}