/* -*- 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 <linux/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); }