/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*- * vim:expandtab:shiftwidth=8:tabstop=8: * * Copyright (c) 2002, 2003 Cluster File Systems, Inc. * Author: Peter Braam * Author: Phil Schwan * * This file is part of Lustre, http://www.lustre.org. * * Lustre is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. * * Lustre 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 Lustre; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #define DEBUG_SUBSYSTEM S_LDLM #ifdef __KERNEL__ #include #include #include #include #include #else #include #endif #include "ldlm_internal.h" #define l_flock_waitq l_lru static struct list_head ldlm_flock_waitq = LIST_HEAD_INIT(ldlm_flock_waitq); int ldlm_flock_blocking_ast(struct ldlm_lock *lock, struct ldlm_lock_desc *desc, void *data, int flag); /** * list_for_remaining_safe - iterate over the remaining entries in a list * and safeguard against removal of a list entry. * @pos: the &struct list_head to use as a loop counter. pos MUST * have been initialized prior to using it in this macro. * @n: another &struct list_head to use as temporary storage * @head: the head for your list. */ #define list_for_remaining_safe(pos, n, head) \ for (n = pos->next; pos != (head); pos = n, n = pos->next) static inline int ldlm_same_flock_owner(struct ldlm_lock *lock, struct ldlm_lock *new) { return((new->l_policy_data.l_flock.pid == lock->l_policy_data.l_flock.pid) && (new->l_export == lock->l_export)); } static inline int ldlm_flocks_overlap(struct ldlm_lock *lock, struct ldlm_lock *new) { return((new->l_policy_data.l_flock.start <= lock->l_policy_data.l_flock.end) && (new->l_policy_data.l_flock.end >= lock->l_policy_data.l_flock.start)); } static inline void ldlm_flock_destroy(struct ldlm_lock *lock, ldlm_mode_t mode, int flags) { ENTRY; LDLM_DEBUG(lock, "ldlm_flock_destroy(mode: %d, flags: 0x%x)", mode, flags); LASSERT(list_empty(&lock->l_flock_waitq)); list_del_init(&lock->l_res_link); if (flags == LDLM_FL_WAIT_NOREPROC) { /* client side - set a flag to prevent sending a CANCEL */ lock->l_flags |= LDLM_FL_LOCAL_ONLY | LDLM_FL_CBPENDING; ldlm_lock_decref_internal(lock, mode); } ldlm_lock_destroy(lock); EXIT; } static int ldlm_flock_deadlock(struct ldlm_lock *req, struct ldlm_lock *blocking_lock) { struct obd_export *req_export = req->l_export; struct obd_export *blocking_export = blocking_lock->l_export; pid_t req_pid = req->l_policy_data.l_flock.pid; pid_t blocking_pid = blocking_lock->l_policy_data.l_flock.pid; struct ldlm_lock *lock; restart: list_for_each_entry(lock, &ldlm_flock_waitq, l_flock_waitq) { if ((lock->l_policy_data.l_flock.pid != blocking_pid) || (lock->l_export != blocking_export)) continue; blocking_pid = lock->l_policy_data.l_flock.blocking_pid; blocking_export = (struct obd_export *)(long) lock->l_policy_data.l_flock.blocking_export; if (blocking_pid == req_pid && blocking_export == req_export) return 1; goto restart; } return 0; } int ldlm_process_flock_lock(struct ldlm_lock *req, int *flags, int first_enq, ldlm_error_t *err) { struct ldlm_resource *res = req->l_resource; struct ldlm_namespace *ns = res->lr_namespace; struct list_head *tmp; struct list_head *ownlocks = NULL; struct ldlm_lock *lock = NULL; struct ldlm_lock *new = req; struct ldlm_lock *new2 = NULL; ldlm_mode_t mode = req->l_req_mode; int local = ns->ns_client; int added = (mode == LCK_NL); int overlaps = 0; ENTRY; CDEBUG(D_DLMTRACE, "flags %#x pid "LPU64" mode %u start "LPU64" end " LPU64"\n", *flags, new->l_policy_data.l_flock.pid, mode, req->l_policy_data.l_flock.start, req->l_policy_data.l_flock.end); *err = ELDLM_OK; if (local) { /* No blocking ASTs are sent to the clients for * Posix file & record locks */ req->l_blocking_ast = NULL; } else { /* Called on the server for lock cancels. */ req->l_blocking_ast = ldlm_flock_blocking_ast; } if ((*flags == LDLM_FL_WAIT_NOREPROC) || (mode == LCK_NL)) { /* This loop determines where this processes locks start * in the resource lr_granted list. */ list_for_each(tmp, &res->lr_granted) { lock = list_entry(tmp, struct ldlm_lock, l_res_link); if (ldlm_same_flock_owner(lock, req)) { ownlocks = tmp; break; } } } else { lockmode_verify(mode); /* This loop determines if there are existing locks * that conflict with the new lock request. */ list_for_each(tmp, &res->lr_granted) { lock = list_entry(tmp, struct ldlm_lock, l_res_link); if (ldlm_same_flock_owner(lock, req)) { if (!ownlocks) ownlocks = tmp; continue; } /* locks are compatible, overlap doesn't matter */ if (lockmode_compat(lock->l_granted_mode, mode)) continue; if (!ldlm_flocks_overlap(lock, req)) continue; if (!first_enq) RETURN(LDLM_ITER_CONTINUE); if (*flags & LDLM_FL_BLOCK_NOWAIT) { ldlm_flock_destroy(req, mode, *flags); *err = -EAGAIN; RETURN(LDLM_ITER_STOP); } if (*flags & LDLM_FL_TEST_LOCK) { ldlm_flock_destroy(req, mode, *flags); req->l_req_mode = lock->l_granted_mode; req->l_policy_data.l_flock.pid = lock->l_policy_data.l_flock.pid; req->l_policy_data.l_flock.start = lock->l_policy_data.l_flock.start; req->l_policy_data.l_flock.end = lock->l_policy_data.l_flock.end; *flags |= LDLM_FL_LOCK_CHANGED; RETURN(LDLM_ITER_STOP); } if (ldlm_flock_deadlock(req, lock)) { ldlm_flock_destroy(req, mode, *flags); *err = -EDEADLK; RETURN(LDLM_ITER_STOP); } req->l_policy_data.l_flock.blocking_pid = lock->l_policy_data.l_flock.pid; req->l_policy_data.l_flock.blocking_export = (long)(void *)lock->l_export; LASSERT(list_empty(&req->l_flock_waitq)); list_add_tail(&req->l_flock_waitq, &ldlm_flock_waitq); ldlm_resource_add_lock(res, &res->lr_waiting, req); *flags |= LDLM_FL_BLOCK_GRANTED; RETURN(LDLM_ITER_STOP); } } if (*flags & LDLM_FL_TEST_LOCK) { ldlm_flock_destroy(req, mode, *flags); req->l_req_mode = LCK_NL; *flags |= LDLM_FL_LOCK_CHANGED; RETURN(LDLM_ITER_STOP); } /* In case we had slept on this lock request take it off of the * deadlock detection waitq. */ list_del_init(&req->l_flock_waitq); /* Scan the locks owned by this process that overlap this request. * We may have to merge or split existing locks. */ if (!ownlocks) ownlocks = &res->lr_granted; list_for_remaining_safe(ownlocks, tmp, &res->lr_granted) { lock = list_entry(ownlocks, struct ldlm_lock, l_res_link); if (!ldlm_same_flock_owner(lock, new)) break; if (lock->l_granted_mode == mode) { /* If the modes are the same then we need to process * locks that overlap OR adjoin the new lock. The extra * logic condition is necessary to deal with arithmetic * overflow and underflow. */ if ((new->l_policy_data.l_flock.start > (lock->l_policy_data.l_flock.end + 1)) && (lock->l_policy_data.l_flock.end != ~0)) continue; if ((new->l_policy_data.l_flock.end < (lock->l_policy_data.l_flock.start - 1)) && (lock->l_policy_data.l_flock.start != 0)) break; if (new->l_policy_data.l_flock.start < lock->l_policy_data.l_flock.start) { lock->l_policy_data.l_flock.start = new->l_policy_data.l_flock.start; } else { new->l_policy_data.l_flock.start = lock->l_policy_data.l_flock.start; } if (new->l_policy_data.l_flock.end > lock->l_policy_data.l_flock.end) { lock->l_policy_data.l_flock.end = new->l_policy_data.l_flock.end; } else { new->l_policy_data.l_flock.end = lock->l_policy_data.l_flock.end; } if (added) { ldlm_flock_destroy(lock, mode, *flags); } else { new = lock; added = 1; } continue; } if (new->l_policy_data.l_flock.start > lock->l_policy_data.l_flock.end) continue; if (new->l_policy_data.l_flock.end < lock->l_policy_data.l_flock.start) break; ++overlaps; if (new->l_policy_data.l_flock.start <= lock->l_policy_data.l_flock.start) { if (new->l_policy_data.l_flock.end < lock->l_policy_data.l_flock.end) { lock->l_policy_data.l_flock.start = new->l_policy_data.l_flock.end + 1; break; } ldlm_flock_destroy(lock, lock->l_req_mode, *flags); continue; } if (new->l_policy_data.l_flock.end >= lock->l_policy_data.l_flock.end) { lock->l_policy_data.l_flock.end = new->l_policy_data.l_flock.start - 1; continue; } /* split the existing lock into two locks */ /* if this is an F_UNLCK operation then we could avoid * allocating a new lock and use the req lock passed in * with the request but this would complicate the reply * processing since updates to req get reflected in the * reply. The client side replays the lock request so * it must see the original lock data in the reply. */ /* XXX - if ldlm_lock_new() can sleep we should * release the ns_lock, allocate the new lock, * and restart processing this lock. */ new2 = ldlm_lock_create(ns, NULL, res->lr_name, LDLM_FLOCK, lock->l_granted_mode, NULL, NULL, NULL, NULL, 0); if (!new2) { ldlm_flock_destroy(req, lock->l_granted_mode, *flags); *err = -ENOLCK; RETURN(LDLM_ITER_STOP); } new2->l_granted_mode = lock->l_granted_mode; new2->l_policy_data.l_flock.pid = new->l_policy_data.l_flock.pid; new2->l_policy_data.l_flock.start = lock->l_policy_data.l_flock.start; new2->l_policy_data.l_flock.end = new->l_policy_data.l_flock.start - 1; lock->l_policy_data.l_flock.start = new->l_policy_data.l_flock.end + 1; new2->l_conn_export = lock->l_conn_export; if (lock->l_export != NULL) { new2->l_export = class_export_get(lock->l_export); list_add(&new2->l_export_chain, &new2->l_export->exp_ldlm_data.led_held_locks); } if (*flags == LDLM_FL_WAIT_NOREPROC) ldlm_lock_addref_internal(new2, lock->l_granted_mode); /* insert new2 at lock */ ldlm_resource_add_lock(res, ownlocks, new2); LDLM_LOCK_PUT(new2); break; } /* Add req to the granted queue before calling ldlm_reprocess_all(). */ if (!added) { req->l_granted_mode = req->l_req_mode; list_del_init(&req->l_res_link); /* insert new lock before ownlocks in list. */ ldlm_resource_add_lock(res, ownlocks, req); } if (*flags != LDLM_FL_WAIT_NOREPROC) { if (first_enq) { /* If this is an unlock, reprocess the waitq and * send completions ASTs for locks that can now be * granted. The only problem with doing this * reprocessing here is that the completion ASTs for * newly granted locks will be sent before the unlock * completion is sent. It shouldn't be an issue. Also * note that ldlm_process_flock_lock() will recurse, * but only once because first_enq will be false from * ldlm_reprocess_queue. */ if ((mode == LCK_NL) && overlaps) { struct list_head rpc_list = LIST_HEAD_INIT(rpc_list); int rc; restart: res->lr_tmp = &rpc_list; ldlm_reprocess_queue(res, &res->lr_waiting); res->lr_tmp = NULL; l_unlock(&ns->ns_lock); rc = ldlm_run_ast_work(res->lr_namespace, &rpc_list); l_lock(&ns->ns_lock); if (rc == -ERESTART) GOTO(restart, -ERESTART); } } else { LASSERT(req->l_completion_ast); ldlm_add_ast_work_item(req, NULL, NULL, 0); } } /* In case we're reprocessing the requested lock we can't destroy * it until after calling ldlm_ast_work_item() above so that lawi() * can bump the reference count on req. Otherwise req could be freed * before the completion AST can be sent. */ if (added) ldlm_flock_destroy(req, mode, *flags); ldlm_resource_dump(res); RETURN(LDLM_ITER_CONTINUE); } struct ldlm_flock_wait_data { struct ldlm_lock *fwd_lock; int fwd_generation; }; static void ldlm_flock_interrupted_wait(void *data) { struct ldlm_lock *lock; struct lustre_handle lockh; int rc; ENTRY; lock = ((struct ldlm_flock_wait_data *)data)->fwd_lock; /* take lock off the deadlock detection waitq. */ list_del_init(&lock->l_flock_waitq); ldlm_lock_decref_internal(lock, lock->l_req_mode); ldlm_lock2handle(lock, &lockh); rc = ldlm_cli_cancel(&lockh); EXIT; } int ldlm_flock_completion_ast(struct ldlm_lock *lock, int flags, void *data) { struct ldlm_namespace *ns; struct file_lock *getlk = lock->l_ast_data; struct ldlm_flock_wait_data fwd; unsigned long irqflags; struct obd_device *obd; struct obd_import *imp = NULL; ldlm_error_t err; int rc = 0; struct l_wait_info lwi; ENTRY; CDEBUG(D_DLMTRACE, "flags: 0x%x data: %p getlk: %p\n", flags, data, getlk); LASSERT(flags != LDLM_FL_WAIT_NOREPROC); if (flags == 0) { wake_up(&lock->l_waitq); RETURN(0); } if (!(flags & (LDLM_FL_BLOCK_WAIT | LDLM_FL_BLOCK_GRANTED | LDLM_FL_BLOCK_CONV))) goto granted; LDLM_DEBUG(lock, "client-side enqueue returned a blocked lock, " "sleeping"); ldlm_lock_dump(D_DLMTRACE, lock, 0); fwd.fwd_lock = lock; obd = class_exp2obd(lock->l_conn_export); /* if this is a local lock, then there is no import */ if (obd != NULL) imp = obd->u.cli.cl_import; if (imp != NULL) { spin_lock_irqsave(&imp->imp_lock, irqflags); fwd.fwd_generation = imp->imp_generation; spin_unlock_irqrestore(&imp->imp_lock, irqflags); } lwi = LWI_TIMEOUT_INTR(0,NULL,ldlm_flock_interrupted_wait,&fwd); /* Go to sleep until the lock is granted. */ rc = l_wait_event(lock->l_waitq, ((lock->l_req_mode == lock->l_granted_mode) || lock->l_destroyed), &lwi); if (rc) { LDLM_DEBUG(lock, "client-side enqueue waking up: failed (%d)", rc); RETURN(rc); } LASSERT(!(lock->l_destroyed)); granted: LDLM_DEBUG(lock, "client-side enqueue waking up"); ns = lock->l_resource->lr_namespace; l_lock(&ns->ns_lock); /* take lock off the deadlock detection waitq. */ list_del_init(&lock->l_flock_waitq); /* ldlm_lock_enqueue() has already placed lock on the granted list. */ list_del_init(&lock->l_res_link); if (flags & LDLM_FL_TEST_LOCK) { /* fcntl(F_GETLK) request */ /* The old mode was saved in getlk->fl_type so that if the mode * in the lock changes we can decref the approprate refcount. */ ldlm_flock_destroy(lock, getlk->fl_type, LDLM_FL_WAIT_NOREPROC); switch (lock->l_granted_mode) { case LCK_PR: getlk->fl_type = F_RDLCK; break; case LCK_PW: getlk->fl_type = F_WRLCK; break; default: getlk->fl_type = F_UNLCK; } getlk->fl_pid = lock->l_policy_data.l_flock.pid; getlk->fl_start = lock->l_policy_data.l_flock.start; getlk->fl_end = lock->l_policy_data.l_flock.end; } else { /* We need to reprocess the lock to do merges or splits * with existing locks owned by this process. */ flags = LDLM_FL_WAIT_NOREPROC; ldlm_process_flock_lock(lock, &flags, 1, &err); } l_unlock(&ns->ns_lock); RETURN(0); } int ldlm_flock_blocking_ast(struct ldlm_lock *lock, struct ldlm_lock_desc *desc, void *data, int flag) { struct ldlm_namespace *ns; ENTRY; LASSERT(lock); LASSERT(flag == LDLM_CB_CANCELING); ns = lock->l_resource->lr_namespace; /* take lock off the deadlock detection waitq. */ l_lock(&ns->ns_lock); list_del_init(&lock->l_flock_waitq); l_unlock(&ns->ns_lock); RETURN(0); }