[GFS2] The lock modules for GFS2

This patch contains the pluggable locking modules
for GFS2.

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

1 files changed, 537 insertions, 0 deletions

diff --git a/fs/gfs2/locking/dlm/lock.c b/fs/gfs2/locking/dlm/lock.c
new file mode 100644
index 000000000000..daf59d504e29
--- /dev/null
+++ b/fs/gfs2/locking/dlm/lock.c
@@ -0,0 +1,537 @@
+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2005 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 v.2.
+**
+*******************************************************************************
+******************************************************************************/
+
+#include "lock_dlm.h"
+
+static char junk_lvb[GDLM_LVB_SIZE];
+
+static void queue_complete(struct gdlm_lock *lp)
+{
+        struct gdlm_ls *ls = lp->ls;
+
+        clear_bit(LFL_ACTIVE, &lp->flags);
+
+        spin_lock(&ls->async_lock);
+        list_add_tail(&lp->clist, &ls->complete);
+        spin_unlock(&ls->async_lock);
+        wake_up(&ls->thread_wait);
+}
+
+static inline void gdlm_ast(void *astarg)
+{
+        queue_complete((struct gdlm_lock *) astarg);
+}
+
+static inline void gdlm_bast(void *astarg, int mode)
+{
+        struct gdlm_lock *lp = astarg;
+        struct gdlm_ls *ls = lp->ls;
+
+        if (!mode) {
+                printk("lock_dlm: bast mode zero %x,%"PRIx64"\n",
+                        lp->lockname.ln_type, lp->lockname.ln_number);
+                return;
+        }
+
+        spin_lock(&ls->async_lock);
+        if (!lp->bast_mode) {
+                list_add_tail(&lp->blist, &ls->blocking);
+                lp->bast_mode = mode;
+        } else if (lp->bast_mode < mode)
+                lp->bast_mode = mode;
+        spin_unlock(&ls->async_lock);
+        wake_up(&ls->thread_wait);
+}
+
+void gdlm_queue_delayed(struct gdlm_lock *lp)
+{
+        struct gdlm_ls *ls = lp->ls;
+
+        spin_lock(&ls->async_lock);
+        list_add_tail(&lp->delay_list, &ls->delayed);
+        spin_unlock(&ls->async_lock);
+}
+
+/* convert gfs lock-state to dlm lock-mode */
+
+static int16_t make_mode(int16_t 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;
+        default:
+                GDLM_ASSERT(0, printk("unknown LM state %d\n", lmstate););
+        }
+}
+
+/* convert dlm lock-mode to gfs lock-state */
+
+int16_t gdlm_make_lmstate(int16_t dlmmode)
+{
+        switch (dlmmode) {
+        case DLM_LOCK_IV:
+        case DLM_LOCK_NL:
+                return LM_ST_UNLOCKED;
+        case DLM_LOCK_EX:
+                return LM_ST_EXCLUSIVE;
+        case DLM_LOCK_CW:
+                return LM_ST_DEFERRED;
+        case DLM_LOCK_PR:
+                return LM_ST_SHARED;
+        default:
+                GDLM_ASSERT(0, printk("unknown DLM mode %d\n", dlmmode););
+        }
+}
+
+/* verify agreement with GFS on the current lock state, NB: DLM_LOCK_NL and
+   DLM_LOCK_IV are both considered LM_ST_UNLOCKED by GFS. */
+
+static void check_cur_state(struct gdlm_lock *lp, unsigned int cur_state)
+{
+        int16_t cur = make_mode(cur_state);
+        if (lp->cur != DLM_LOCK_IV)
+                GDLM_ASSERT(lp->cur == cur, printk("%d, %d\n", lp->cur, cur););
+}
+
+static inline unsigned int make_flags(struct gdlm_lock *lp,
+                                      unsigned int gfs_flags,
+                                      int16_t cur, int16_t req)
+{
+        unsigned int 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;
+        }
+
+        if (lp->lksb.sb_lkid != 0) {
+                lkf |= DLM_LKF_CONVERT;
+
+                /* Conversion deadlock avoidance by DLM */
+
+                if (!test_bit(LFL_FORCE_PROMOTE, &lp->flags) &&
+                    !(lkf & DLM_LKF_NOQUEUE) &&
+                    cur > DLM_LOCK_NL && req > DLM_LOCK_NL && cur != req)
+                        lkf |= DLM_LKF_CONVDEADLK;
+        }
+
+        if (lp->lvb)
+                lkf |= DLM_LKF_VALBLK;
+
+        return lkf;
+}
+
+/* make_strname - convert GFS lock numbers to a string */
+
+static inline void make_strname(struct lm_lockname *lockname,
+                                struct gdlm_strname *str)
+{
+        sprintf(str->name, "%8x%16"PRIx64, lockname->ln_type,
+                lockname->ln_number);
+        str->namelen = GDLM_STRNAME_BYTES;
+}
+
+int gdlm_create_lp(struct gdlm_ls *ls, struct lm_lockname *name,
+                   struct gdlm_lock **lpp)
+{
+        struct gdlm_lock *lp;
+
+        lp = kmalloc(sizeof(struct gdlm_lock), GFP_KERNEL);
+        if (!lp)
+                return -ENOMEM;
+
+        memset(lp, 0, sizeof(struct gdlm_lock));
+        lp->lockname = *name;
+        lp->ls = ls;
+        lp->cur = DLM_LOCK_IV;
+        lp->lvb = NULL;
+        lp->hold_null = NULL;
+        init_completion(&lp->ast_wait);
+        INIT_LIST_HEAD(&lp->clist);
+        INIT_LIST_HEAD(&lp->blist);
+        INIT_LIST_HEAD(&lp->delay_list);
+
+        spin_lock(&ls->async_lock);
+        list_add(&lp->all_list, &ls->all_locks);
+        ls->all_locks_count++;
+        spin_unlock(&ls->async_lock);
+
+        *lpp = lp;
+        return 0;
+}
+
+void gdlm_delete_lp(struct gdlm_lock *lp)
+{
+        struct gdlm_ls *ls = lp->ls;
+
+        spin_lock(&ls->async_lock);
+        if (!list_empty(&lp->clist))
+                list_del_init(&lp->clist);
+        if (!list_empty(&lp->blist))
+                list_del_init(&lp->blist);
+        if (!list_empty(&lp->delay_list))
+                list_del_init(&lp->delay_list);
+        GDLM_ASSERT(!list_empty(&lp->all_list),);
+        list_del_init(&lp->all_list);
+        ls->all_locks_count--;
+        spin_unlock(&ls->async_lock);
+
+        kfree(lp);
+}
+
+int gdlm_get_lock(lm_lockspace_t *lockspace, struct lm_lockname *name,
+                  lm_lock_t **lockp)
+{
+        struct gdlm_lock *lp;
+        int error;
+
+        error = gdlm_create_lp((struct gdlm_ls *) lockspace, name, &lp);
+
+        *lockp = (lm_lock_t *) lp;
+        return error;
+}
+
+void gdlm_put_lock(lm_lock_t *lock)
+{
+        gdlm_delete_lp((struct gdlm_lock *) lock);
+}
+
+void gdlm_do_lock(struct gdlm_lock *lp, struct dlm_range *range)
+{
+        struct gdlm_ls *ls = lp->ls;
+        struct gdlm_strname str;
+        int error, bast = 1;
+
+        /*
+         * When recovery is in progress, delay lock requests for submission
+         * once recovery is done.  Requests for recovery (NOEXP) and unlocks
+         * can pass.
+         */
+
+        if (test_bit(DFL_BLOCK_LOCKS, &ls->flags) &&
+            !test_bit(LFL_NOBLOCK, &lp->flags) && lp->req != DLM_LOCK_NL) {
+                gdlm_queue_delayed(lp);
+                return;
+        }
+
+        /*
+         * Submit the actual lock request.
+         */
+
+        if (test_bit(LFL_NOBAST, &lp->flags))
+                bast = 0;
+
+        make_strname(&lp->lockname, &str);
+
+        set_bit(LFL_ACTIVE, &lp->flags);
+
+        log_debug("lk %x,%"PRIx64" id %x %d,%d %x", lp->lockname.ln_type,
+                  lp->lockname.ln_number, lp->lksb.sb_lkid,
+                  lp->cur, lp->req, lp->lkf);
+
+        error = dlm_lock(ls->dlm_lockspace, lp->req, &lp->lksb, lp->lkf,
+                         str.name, str.namelen, 0, gdlm_ast, (void *) lp,
+                         bast ? gdlm_bast : NULL, range);
+
+        if ((error == -EAGAIN) && (lp->lkf & DLM_LKF_NOQUEUE)) {
+                lp->lksb.sb_status = -EAGAIN;
+                queue_complete(lp);
+                error = 0;
+        }
+
+        GDLM_ASSERT(!error,
+                   printk("%s: num=%x,%"PRIx64" err=%d cur=%d req=%d lkf=%x\n",
+                          ls->fsname, lp->lockname.ln_type,
+                          lp->lockname.ln_number, error, lp->cur, lp->req,
+                          lp->lkf););
+}
+
+void gdlm_do_unlock(struct gdlm_lock *lp)
+{
+        unsigned int lkf = 0;
+        int error;
+
+        set_bit(LFL_DLM_UNLOCK, &lp->flags);
+        set_bit(LFL_ACTIVE, &lp->flags);
+
+        if (lp->lvb)
+                lkf = DLM_LKF_VALBLK;
+
+        log_debug("un %x,%"PRIx64" %x %d %x", lp->lockname.ln_type,
+                  lp->lockname.ln_number, lp->lksb.sb_lkid, lp->cur, lkf);
+
+        error = dlm_unlock(lp->ls->dlm_lockspace, lp->lksb.sb_lkid, lkf,
+                           NULL, lp);
+
+        GDLM_ASSERT(!error,
+                   printk("%s: error=%d num=%x,%"PRIx64" lkf=%x flags=%lx\n",
+                          lp->ls->fsname, error, lp->lockname.ln_type,
+                          lp->lockname.ln_number, lkf, lp->flags););
+}
+
+unsigned int gdlm_lock(lm_lock_t *lock, unsigned int cur_state,
+                       unsigned int req_state, unsigned int flags)
+{
+        struct gdlm_lock *lp = (struct gdlm_lock *) lock;
+
+        clear_bit(LFL_DLM_CANCEL, &lp->flags);
+        if (flags & LM_FLAG_NOEXP)
+                set_bit(LFL_NOBLOCK, &lp->flags);
+
+        check_cur_state(lp, cur_state);
+        lp->req = make_mode(req_state);
+        lp->lkf = make_flags(lp, flags, lp->cur, lp->req);
+
+        gdlm_do_lock(lp, NULL);
+        return LM_OUT_ASYNC;
+}
+
+unsigned int gdlm_unlock(lm_lock_t *lock, unsigned int cur_state)
+{
+        struct gdlm_lock *lp = (struct gdlm_lock *) lock;
+
+        clear_bit(LFL_DLM_CANCEL, &lp->flags);
+        if (lp->cur == DLM_LOCK_IV)
+                return 0;
+        gdlm_do_unlock(lp);
+        return LM_OUT_ASYNC;
+}
+
+void gdlm_cancel(lm_lock_t *lock)
+{
+        struct gdlm_lock *lp = (struct gdlm_lock *) lock;
+        struct gdlm_ls *ls = lp->ls;
+        int error, delay_list = 0;
+
+        if (test_bit(LFL_DLM_CANCEL, &lp->flags))
+                return;
+
+        log_all("gdlm_cancel %x,%"PRIx64" flags %lx",
+                lp->lockname.ln_type, lp->lockname.ln_number, lp->flags);
+
+        spin_lock(&ls->async_lock);
+        if (!list_empty(&lp->delay_list)) {
+                list_del_init(&lp->delay_list);
+                delay_list = 1;
+        }
+        spin_unlock(&ls->async_lock);
+
+        if (delay_list) {
+                set_bit(LFL_CANCEL, &lp->flags);
+                set_bit(LFL_ACTIVE, &lp->flags);
+                queue_complete(lp);
+                return;
+        }
+
+        if (!test_bit(LFL_ACTIVE, &lp->flags) ||
+            test_bit(LFL_DLM_UNLOCK, &lp->flags))       {
+                log_all("gdlm_cancel skip %x,%"PRIx64" flags %lx",
+                        lp->lockname.ln_type, lp->lockname.ln_number,
+                        lp->flags);
+                return;
+        }
+
+        /* the lock is blocked in the dlm */
+
+        set_bit(LFL_DLM_CANCEL, &lp->flags);
+        set_bit(LFL_ACTIVE, &lp->flags);
+
+        error = dlm_unlock(ls->dlm_lockspace, lp->lksb.sb_lkid, DLM_LKF_CANCEL,
+                           NULL, lp);
+
+        log_all("gdlm_cancel rv %d %x,%"PRIx64" flags %lx", error,
+                lp->lockname.ln_type, lp->lockname.ln_number, lp->flags);
+
+        if (error == -EBUSY)
+                clear_bit(LFL_DLM_CANCEL, &lp->flags);
+}
+
+int gdlm_add_lvb(struct gdlm_lock *lp)
+{
+        char *lvb;
+
+        lvb = kmalloc(GDLM_LVB_SIZE, GFP_KERNEL);
+        if (!lvb)
+                return -ENOMEM;
+
+        memset(lvb, 0, GDLM_LVB_SIZE);
+
+        lp->lksb.sb_lvbptr = lvb;
+        lp->lvb = lvb;
+        return 0;
+}
+
+void gdlm_del_lvb(struct gdlm_lock *lp)
+{
+        kfree(lp->lvb);
+        lp->lvb = NULL;
+        lp->lksb.sb_lvbptr = NULL;
+}
+
+/* This can do a synchronous dlm request (requiring a lock_dlm thread to get
+   the completion) because gfs won't call hold_lvb() during a callback (from
+   the context of a lock_dlm thread). */
+
+static int hold_null_lock(struct gdlm_lock *lp)
+{
+        struct gdlm_lock *lpn = NULL;
+        int error;
+
+        if (lp->hold_null) {
+                printk("lock_dlm: lvb already held\n");
+                return 0;
+        }
+
+        error = gdlm_create_lp(lp->ls, &lp->lockname, &lpn);
+        if (error)
+                goto out;
+
+        lpn->lksb.sb_lvbptr = junk_lvb;
+        lpn->lvb = junk_lvb;
+
+        lpn->req = DLM_LOCK_NL;
+        lpn->lkf = DLM_LKF_VALBLK | DLM_LKF_EXPEDITE;
+        set_bit(LFL_NOBAST, &lpn->flags);
+        set_bit(LFL_INLOCK, &lpn->flags);
+
+        init_completion(&lpn->ast_wait);
+        gdlm_do_lock(lpn, NULL);
+        wait_for_completion(&lpn->ast_wait);
+        error = lp->lksb.sb_status;
+        if (error) {
+                printk("lock_dlm: hold_null_lock dlm error %d\n", error);
+                gdlm_delete_lp(lpn);
+                lpn = NULL;
+        }
+ out:
+        lp->hold_null = lpn;
+        return error;
+}
+
+/* This cannot do a synchronous dlm request (requiring a lock_dlm thread to get
+   the completion) because gfs may call unhold_lvb() during a callback (from
+   the context of a lock_dlm thread) which could cause a deadlock since the
+   other lock_dlm thread could be engaged in recovery. */
+
+static void unhold_null_lock(struct gdlm_lock *lp)
+{
+        struct gdlm_lock *lpn = lp->hold_null;
+
+        GDLM_ASSERT(lpn,);
+        lpn->lksb.sb_lvbptr = NULL;
+        lpn->lvb = NULL;
+        set_bit(LFL_UNLOCK_DELETE, &lpn->flags);
+        gdlm_do_unlock(lpn);
+        lp->hold_null = NULL;
+}
+
+/* Acquire a NL lock because gfs requires the value block to remain
+   intact on the resource while the lvb is "held" even if it's holding no locks
+   on the resource. */
+
+int gdlm_hold_lvb(lm_lock_t *lock, char **lvbp)
+{
+        struct gdlm_lock *lp = (struct gdlm_lock *) lock;
+        int error;
+
+        error = gdlm_add_lvb(lp);
+        if (error)
+                return error;
+
+        *lvbp = lp->lvb;
+
+        error = hold_null_lock(lp);
+        if (error)
+                gdlm_del_lvb(lp);
+
+        return error;
+}
+
+void gdlm_unhold_lvb(lm_lock_t *lock, char *lvb)
+{
+        struct gdlm_lock *lp = (struct gdlm_lock *) lock;
+
+        unhold_null_lock(lp);
+        gdlm_del_lvb(lp);
+}
+
+void gdlm_sync_lvb(lm_lock_t *lock, char *lvb)
+{
+        struct gdlm_lock *lp = (struct gdlm_lock *) lock;
+
+        if (lp->cur != DLM_LOCK_EX)
+                return;
+
+        init_completion(&lp->ast_wait);
+        set_bit(LFL_SYNC_LVB, &lp->flags);
+
+        lp->req = DLM_LOCK_EX;
+        lp->lkf = make_flags(lp, 0, lp->cur, lp->req);
+
+        gdlm_do_lock(lp, NULL);
+        wait_for_completion(&lp->ast_wait);
+}
+
+void gdlm_submit_delayed(struct gdlm_ls *ls)
+{
+        struct gdlm_lock *lp, *safe;
+
+        spin_lock(&ls->async_lock);
+        list_for_each_entry_safe(lp, safe, &ls->delayed, delay_list) {
+                list_del_init(&lp->delay_list);
+                list_add_tail(&lp->delay_list, &ls->submit);
+        }
+        spin_unlock(&ls->async_lock);
+        wake_up(&ls->thread_wait);
+}
+
+int gdlm_release_all_locks(struct gdlm_ls *ls)
+{
+        struct gdlm_lock *lp, *safe;
+        int count = 0;
+
+        spin_lock(&ls->async_lock);
+        list_for_each_entry_safe(lp, safe, &ls->all_locks, all_list) {
+                list_del_init(&lp->all_list);
+
+                if (lp->lvb && lp->lvb != junk_lvb)
+                        kfree(lp->lvb);
+                kfree(lp);
+                count++;
+        }
+        spin_unlock(&ls->async_lock);
+
+        return count;
+}
+