diff options
Diffstat (limited to 'fs/dlm/lock.c')
| -rw-r--r-- | fs/dlm/lock.c | 3871 |
1 files changed, 3871 insertions, 0 deletions
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c new file mode 100644 index 00000000000..3f2befa4797 --- /dev/null +++ b/fs/dlm/lock.c @@ -0,0 +1,3871 @@ +/****************************************************************************** +******************************************************************************* +** +** Copyright (C) 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. +** +******************************************************************************* +******************************************************************************/ + +/* Central locking logic has four stages: + + dlm_lock() + dlm_unlock() + + request_lock(ls, lkb) + convert_lock(ls, lkb) + unlock_lock(ls, lkb) + cancel_lock(ls, lkb) + + _request_lock(r, lkb) + _convert_lock(r, lkb) + _unlock_lock(r, lkb) + _cancel_lock(r, lkb) + + do_request(r, lkb) + do_convert(r, lkb) + do_unlock(r, lkb) + do_cancel(r, lkb) + + Stage 1 (lock, unlock) is mainly about checking input args and + splitting into one of the four main operations: + + dlm_lock = request_lock + dlm_lock+CONVERT = convert_lock + dlm_unlock = unlock_lock + dlm_unlock+CANCEL = cancel_lock + + Stage 2, xxxx_lock(), just finds and locks the relevant rsb which is + provided to the next stage. + + Stage 3, _xxxx_lock(), determines if the operation is local or remote. + When remote, it calls send_xxxx(), when local it calls do_xxxx(). + + Stage 4, do_xxxx(), is the guts of the operation. It manipulates the + given rsb and lkb and queues callbacks. + + For remote operations, send_xxxx() results in the corresponding do_xxxx() + function being executed on the remote node. The connecting send/receive + calls on local (L) and remote (R) nodes: + + L: send_xxxx() -> R: receive_xxxx() + R: do_xxxx() + L: receive_xxxx_reply() <- R: send_xxxx_reply() +*/ +#include <linux/types.h> +#include "dlm_internal.h" +#include <linux/dlm_device.h> +#include "memory.h" +#include "lowcomms.h" +#include "requestqueue.h" +#include "util.h" +#include "dir.h" +#include "member.h" +#include "lockspace.h" +#include "ast.h" +#include "lock.h" +#include "rcom.h" +#include "recover.h" +#include "lvb_table.h" +#include "user.h" +#include "config.h" + +static int send_request(struct dlm_rsb *r, struct dlm_lkb *lkb); +static int send_convert(struct dlm_rsb *r, struct dlm_lkb *lkb); +static int send_unlock(struct dlm_rsb *r, struct dlm_lkb *lkb); +static int send_cancel(struct dlm_rsb *r, struct dlm_lkb *lkb); +static int send_grant(struct dlm_rsb *r, struct dlm_lkb *lkb); +static int send_bast(struct dlm_rsb *r, struct dlm_lkb *lkb, int mode); +static int send_lookup(struct dlm_rsb *r, struct dlm_lkb *lkb); +static int send_remove(struct dlm_rsb *r); +static int _request_lock(struct dlm_rsb *r, struct dlm_lkb *lkb); +static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb, + struct dlm_message *ms); +static int receive_extralen(struct dlm_message *ms); + +/* + * Lock compatibilty matrix - thanks Steve + * UN = Unlocked state. Not really a state, used as a flag + * PD = Padding. Used to make the matrix a nice power of two in size + * Other states are the same as the VMS DLM. + * Usage: matrix[grmode+1][rqmode+1] (although m[rq+1][gr+1] is the same) + */ + +static const int __dlm_compat_matrix[8][8] = { + /* UN NL CR CW PR PW EX PD */ + {1, 1, 1, 1, 1, 1, 1, 0}, /* UN */ + {1, 1, 1, 1, 1, 1, 1, 0}, /* NL */ + {1, 1, 1, 1, 1, 1, 0, 0}, /* CR */ + {1, 1, 1, 1, 0, 0, 0, 0}, /* CW */ + {1, 1, 1, 0, 1, 0, 0, 0}, /* PR */ + {1, 1, 1, 0, 0, 0, 0, 0}, /* PW */ + {1, 1, 0, 0, 0, 0, 0, 0}, /* EX */ + {0, 0, 0, 0, 0, 0, 0, 0} /* PD */ +}; + +/* + * This defines the direction of transfer of LVB data. + * Granted mode is the row; requested mode is the column. + * Usage: matrix[grmode+1][rqmode+1] + * 1 = LVB is returned to the caller + * 0 = LVB is written to the resource + * -1 = nothing happens to the LVB + */ + +const int dlm_lvb_operations[8][8] = { + /* UN NL CR CW PR PW EX PD*/ + { -1, 1, 1, 1, 1, 1, 1, -1 }, /* UN */ + { -1, 1, 1, 1, 1, 1, 1, 0 }, /* NL */ + { -1, -1, 1, 1, 1, 1, 1, 0 }, /* CR */ + { -1, -1, -1, 1, 1, 1, 1, 0 }, /* CW */ + { -1, -1, -1, -1, 1, 1, 1, 0 }, /* PR */ + { -1, 0, 0, 0, 0, 0, 1, 0 }, /* PW */ + { -1, 0, 0, 0, 0, 0, 0, 0 }, /* EX */ + { -1, 0, 0, 0, 0, 0, 0, 0 } /* PD */ +}; + +#define modes_compat(gr, rq) \ + __dlm_compat_matrix[(gr)->lkb_grmode + 1][(rq)->lkb_rqmode + 1] + +int dlm_modes_compat(int mode1, int mode2) +{ + return __dlm_compat_matrix[mode1 + 1][mode2 + 1]; +} + +/* + * Compatibility matrix for conversions with QUECVT set. + * Granted mode is the row; requested mode is the column. + * Usage: matrix[grmode+1][rqmode+1] + */ + +static const int __quecvt_compat_matrix[8][8] = { + /* UN NL CR CW PR PW EX PD */ + {0, 0, 0, 0, 0, 0, 0, 0}, /* UN */ + {0, 0, 1, 1, 1, 1, 1, 0}, /* NL */ + {0, 0, 0, 1, 1, 1, 1, 0}, /* CR */ + {0, 0, 0, 0, 1, 1, 1, 0}, /* CW */ + {0, 0, 0, 1, 0, 1, 1, 0}, /* PR */ + {0, 0, 0, 0, 0, 0, 1, 0}, /* PW */ + {0, 0, 0, 0, 0, 0, 0, 0}, /* EX */ + {0, 0, 0, 0, 0, 0, 0, 0} /* PD */ +}; + +void dlm_print_lkb(struct dlm_lkb *lkb) +{ + printk(KERN_ERR "lkb: nodeid %d id %x remid %x exflags %x flags %x\n" + " status %d rqmode %d grmode %d wait_type %d ast_type %d\n", + lkb->lkb_nodeid, lkb->lkb_id, lkb->lkb_remid, lkb->lkb_exflags, + lkb->lkb_flags, lkb->lkb_status, lkb->lkb_rqmode, + lkb->lkb_grmode, lkb->lkb_wait_type, lkb->lkb_ast_type); +} + +void dlm_print_rsb(struct dlm_rsb *r) +{ + printk(KERN_ERR "rsb: nodeid %d flags %lx first %x rlc %d name %s\n", + r->res_nodeid, r->res_flags, r->res_first_lkid, + r->res_recover_locks_count, r->res_name); +} + +void dlm_dump_rsb(struct dlm_rsb *r) +{ + struct dlm_lkb *lkb; + + dlm_print_rsb(r); + + printk(KERN_ERR "rsb: root_list empty %d recover_list empty %d\n", + list_empty(&r->res_root_list), list_empty(&r->res_recover_list)); + printk(KERN_ERR "rsb lookup list\n"); + list_for_each_entry(lkb, &r->res_lookup, lkb_rsb_lookup) + dlm_print_lkb(lkb); + printk(KERN_ERR "rsb grant queue:\n"); + list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue) + dlm_print_lkb(lkb); + printk(KERN_ERR "rsb convert queue:\n"); + list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue) + dlm_print_lkb(lkb); + printk(KERN_ERR "rsb wait queue:\n"); + list_for_each_entry(lkb, &r->res_waitqueue, lkb_statequeue) + dlm_print_lkb(lkb); +} + +/* Threads cannot use the lockspace while it's being recovered */ + +static inline void lock_recovery(struct dlm_ls *ls) +{ + down_read(&ls->ls_in_recovery); +} + +static inline void unlock_recovery(struct dlm_ls *ls) +{ + up_read(&ls->ls_in_recovery); +} + +static inline int lock_recovery_try(struct dlm_ls *ls) +{ + return down_read_trylock(&ls->ls_in_recovery); +} + +static inline int can_be_queued(struct dlm_lkb *lkb) +{ + return !(lkb->lkb_exflags & DLM_LKF_NOQUEUE); +} + +static inline int force_blocking_asts(struct dlm_lkb *lkb) +{ + return (lkb->lkb_exflags & DLM_LKF_NOQUEUEBAST); +} + +static inline int is_demoted(struct dlm_lkb *lkb) +{ + return (lkb->lkb_sbflags & DLM_SBF_DEMOTED); +} + +static inline int is_remote(struct dlm_rsb *r) +{ + DLM_ASSERT(r->res_nodeid >= 0, dlm_print_rsb(r);); + return !!r->res_nodeid; +} + +static inline int is_process_copy(struct dlm_lkb *lkb) +{ + return (lkb->lkb_nodeid && !(lkb->lkb_flags & DLM_IFL_MSTCPY)); +} + +static inline int is_master_copy(struct dlm_lkb *lkb) +{ + if (lkb->lkb_flags & DLM_IFL_MSTCPY) + DLM_ASSERT(lkb->lkb_nodeid, dlm_print_lkb(lkb);); + return (lkb->lkb_flags & DLM_IFL_MSTCPY) ? 1 : 0; +} + +static inline int middle_conversion(struct dlm_lkb *lkb) +{ + if ((lkb->lkb_grmode==DLM_LOCK_PR && lkb->lkb_rqmode==DLM_LOCK_CW) || + (lkb->lkb_rqmode==DLM_LOCK_PR && lkb->lkb_grmode==DLM_LOCK_CW)) + return 1; + return 0; +} + +static inline int down_conversion(struct dlm_lkb *lkb) +{ + return (!middle_conversion(lkb) && lkb->lkb_rqmode < lkb->lkb_grmode); +} + +static void queue_cast(struct dlm_rsb *r, struct dlm_lkb *lkb, int rv) +{ + if (is_master_copy(lkb)) + return; + + DLM_ASSERT(lkb->lkb_lksb, dlm_print_lkb(lkb);); + + lkb->lkb_lksb->sb_status = rv; + lkb->lkb_lksb->sb_flags = lkb->lkb_sbflags; + + dlm_add_ast(lkb, AST_COMP); +} + +static void queue_bast(struct dlm_rsb *r, struct dlm_lkb *lkb, int rqmode) +{ + if (is_master_copy(lkb)) + send_bast(r, lkb, rqmode); + else { + lkb->lkb_bastmode = rqmode; + dlm_add_ast(lkb, AST_BAST); + } +} + +/* + * Basic operations on rsb's and lkb's + */ + +static struct dlm_rsb *create_rsb(struct dlm_ls *ls, char *name, int len) +{ + struct dlm_rsb *r; + + r = allocate_rsb(ls, len); + if (!r) + return NULL; + + r->res_ls = ls; + r->res_length = len; + memcpy(r->res_name, name, len); + mutex_init(&r->res_mutex); + + INIT_LIST_HEAD(&r->res_lookup); + INIT_LIST_HEAD(&r->res_grantqueue); + INIT_LIST_HEAD(&r->res_convertqueue); + INIT_LIST_HEAD(&r->res_waitqueue); + INIT_LIST_HEAD(&r->res_root_list); + INIT_LIST_HEAD(&r->res_recover_list); + + return r; +} + +static int search_rsb_list(struct list_head *head, char *name, int len, + unsigned int flags, struct dlm_rsb **r_ret) +{ + struct dlm_rsb *r; + int error = 0; + + list_for_each_entry(r, head, res_hashchain) { + if (len == r->res_length && !memcmp(name, r->res_name, len)) + goto found; + } + return -EBADR; + + found: + if (r->res_nodeid && (flags & R_MASTER)) + error = -ENOTBLK; + *r_ret = r; + return error; +} + +static int _search_rsb(struct dlm_ls *ls, char *name, int len, int b, + unsigned int flags, struct dlm_rsb **r_ret) +{ + struct dlm_rsb *r; + int error; + + error = search_rsb_list(&ls->ls_rsbtbl[b].list, name, len, flags, &r); + if (!error) { + kref_get(&r->res_ref); + goto out; + } + error = search_rsb_list(&ls->ls_rsbtbl[b].toss, name, len, flags, &r); + if (error) + goto out; + + list_move(&r->res_hashchain, &ls->ls_rsbtbl[b].list); + + if (dlm_no_directory(ls)) + goto out; + + if (r->res_nodeid == -1) { + rsb_clear_flag(r, RSB_MASTER_UNCERTAIN); + r->res_first_lkid = 0; + } else if (r->res_nodeid > 0) { + rsb_set_flag(r, RSB_MASTER_UNCERTAIN); + r->res_first_lkid = 0; + } else { + DLM_ASSERT(r->res_nodeid == 0, dlm_print_rsb(r);); + DLM_ASSERT(!rsb_flag(r, RSB_MASTER_UNCERTAIN),); + } + out: + *r_ret = r; + return error; +} + +static int search_rsb(struct dlm_ls *ls, char *name, int len, int b, + unsigned int flags, struct dlm_rsb **r_ret) +{ + int error; + write_lock(&ls->ls_rsbtbl[b].lock); + error = _search_rsb(ls, name, len, b, flags, r_ret); + write_unlock(&ls->ls_rsbtbl[b].lock); + return error; +} + +/* + * Find rsb in rsbtbl and potentially create/add one + * + * Delaying the release of rsb's has a similar benefit to applications keeping + * NL locks on an rsb, but without the guarantee that the cached master value + * will still be valid when the rsb is reused. Apps aren't always smart enough + * to keep NL locks on an rsb that they may lock again shortly; this can lead + * to excessive master lookups and removals if we don't delay the release. + * + * Searching for an rsb means looking through both the normal list and toss + * list. When found on the toss list the rsb is moved to the normal list with + * ref count of 1; when found on normal list the ref count is incremented. + */ + +static int find_rsb(struct dlm_ls *ls, char *name, int namelen, + unsigned int flags, struct dlm_rsb **r_ret) +{ + struct dlm_rsb *r, *tmp; + uint32_t hash, bucket; + int error = 0; + + if (dlm_no_directory(ls)) + flags |= R_CREATE; + + hash = jhash(name, namelen, 0); + bucket = hash & (ls->ls_rsbtbl_size - 1); + + error = search_rsb(ls, name, namelen, bucket, flags, &r); + if (!error) + goto out; + + if (error == -EBADR && !(flags & R_CREATE)) + goto out; + + /* the rsb was found but wasn't a master copy */ + if (error == -ENOTBLK) + goto out; + + error = -ENOMEM; + r = create_rsb(ls, name, namelen); + if (!r) + goto out; + + r->res_hash = hash; + r->res_bucket = bucket; + r->res_nodeid = -1; + kref_init(&r->res_ref); + + /* With no directory, the master can be set immediately */ + if (dlm_no_directory(ls)) { + int nodeid = dlm_dir_nodeid(r); + if (nodeid == dlm_our_nodeid()) + nodeid = 0; + r->res_nodeid = nodeid; + } + + write_lock(&ls->ls_rsbtbl[bucket].lock); + error = _search_rsb(ls, name, namelen, bucket, 0, &tmp); + if (!error) { + write_unlock(&ls->ls_rsbtbl[bucket].lock); + free_rsb(r); + r = tmp; + goto out; + } + list_add(&r->res_hashchain, &ls->ls_rsbtbl[bucket].list); + write_unlock(&ls->ls_rsbtbl[bucket].lock); + error = 0; + out: + *r_ret = r; + return error; +} + +int dlm_find_rsb(struct dlm_ls *ls, char *name, int namelen, + unsigned int flags, struct dlm_rsb **r_ret) +{ + return find_rsb(ls, name, namelen, flags, r_ret); +} + +/* This is only called to add a reference when the code already holds + a valid reference to the rsb, so there's no need for locking. */ + +static inline void hold_rsb(struct dlm_rsb *r) +{ + kref_get(&r->res_ref); +} + +void dlm_hold_rsb(struct dlm_rsb *r) +{ + hold_rsb(r); +} + +static void toss_rsb(struct kref *kref) +{ + struct dlm_rsb *r = container_of(kref, struct dlm_rsb, res_ref); + struct dlm_ls *ls = r->res_ls; + + DLM_ASSERT(list_empty(&r->res_root_list), dlm_print_rsb(r);); + kref_init(&r->res_ref); + list_move(&r->res_hashchain, &ls->ls_rsbtbl[r->res_bucket].toss); + r->res_toss_time = jiffies; + if (r->res_lvbptr) { + free_lvb(r->res_lvbptr); + r->res_lvbptr = NULL; + } +} + +/* When all references to the rsb are gone it's transfered to + the tossed list for later disposal. */ + +static void put_rsb(struct dlm_rsb *r) +{ + struct dlm_ls *ls = r->res_ls; + uint32_t bucket = r->res_bucket; + + write_lock(&ls->ls_rsbtbl[bucket].lock); + kref_put(&r->res_ref, toss_rsb); + write_unlock(&ls->ls_rsbtbl[bucket].lock); +} + +void dlm_put_rsb(struct dlm_rsb *r) +{ + put_rsb(r); +} + +/* See comment for unhold_lkb */ + +static void unhold_rsb(struct dlm_rsb *r) +{ + int rv; + rv = kref_put(&r->res_ref, toss_rsb); + DLM_ASSERT(!rv, dlm_dump_rsb(r);); +} + +static void kill_rsb(struct kref *kref) +{ + struct dlm_rsb *r = container_of(kref, struct dlm_rsb, res_ref); + + /* All work is done after the return from kref_put() so we + can release the write_lock before the remove and free. */ + + DLM_ASSERT(list_empty(&r->res_lookup), dlm_dump_rsb(r);); + DLM_ASSERT(list_empty(&r->res_grantqueue), dlm_dump_rsb(r);); + DLM_ASSERT(list_empty(&r->res_convertqueue), dlm_dump_rsb(r);); + DLM_ASSERT(list_empty(&r->res_waitqueue), dlm_dump_rsb(r);); + DLM_ASSERT(list_empty(&r->res_root_list), dlm_dump_rsb(r);); + DLM_ASSERT(list_empty(&r->res_recover_list), dlm_dump_rsb(r);); +} + +/* Attaching/detaching lkb's from rsb's is for rsb reference counting. + The rsb must exist as long as any lkb's for it do. */ + +static void attach_lkb(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + hold_rsb(r); + lkb->lkb_resource = r; +} + +static void detach_lkb(struct dlm_lkb *lkb) +{ + if (lkb->lkb_resource) { + put_rsb(lkb->lkb_resource); + lkb->lkb_resource = NULL; + } +} + +static int create_lkb(struct dlm_ls *ls, struct dlm_lkb **lkb_ret) +{ + struct dlm_lkb *lkb, *tmp; + uint32_t lkid = 0; + uint16_t bucket; + + lkb = allocate_lkb(ls); + if (!lkb) + return -ENOMEM; + + lkb->lkb_nodeid = -1; + lkb->lkb_grmode = DLM_LOCK_IV; + kref_init(&lkb->lkb_ref); + INIT_LIST_HEAD(&lkb->lkb_ownqueue); + + get_random_bytes(&bucket, sizeof(bucket)); + bucket &= (ls->ls_lkbtbl_size - 1); + + write_lock(&ls->ls_lkbtbl[bucket].lock); + + /* counter can roll over so we must verify lkid is not in use */ + + while (lkid == 0) { + lkid = bucket | (ls->ls_lkbtbl[bucket].counter++ << 16); + + list_for_each_entry(tmp, &ls->ls_lkbtbl[bucket].list, + lkb_idtbl_list) { + if (tmp->lkb_id != lkid) + continue; + lkid = 0; + break; + } + } + + lkb->lkb_id = lkid; + list_add(&lkb->lkb_idtbl_list, &ls->ls_lkbtbl[bucket].list); + write_unlock(&ls->ls_lkbtbl[bucket].lock); + + *lkb_ret = lkb; + return 0; +} + +static struct dlm_lkb *__find_lkb(struct dlm_ls *ls, uint32_t lkid) +{ + uint16_t bucket = lkid & 0xFFFF; + struct dlm_lkb *lkb; + + list_for_each_entry(lkb, &ls->ls_lkbtbl[bucket].list, lkb_idtbl_list) { + if (lkb->lkb_id == lkid) + return lkb; + } + return NULL; +} + +static int find_lkb(struct dlm_ls *ls, uint32_t lkid, struct dlm_lkb **lkb_ret) +{ + struct dlm_lkb *lkb; + uint16_t bucket = lkid & 0xFFFF; + + if (bucket >= ls->ls_lkbtbl_size) + return -EBADSLT; + + read_lock(&ls->ls_lkbtbl[bucket].lock); + lkb = __find_lkb(ls, lkid); + if (lkb) + kref_get(&lkb->lkb_ref); + read_unlock(&ls->ls_lkbtbl[bucket].lock); + + *lkb_ret = lkb; + return lkb ? 0 : -ENOENT; +} + +static void kill_lkb(struct kref *kref) +{ + struct dlm_lkb *lkb = container_of(kref, struct dlm_lkb, lkb_ref); + + /* All work is done after the return from kref_put() so we + can release the write_lock before the detach_lkb */ + + DLM_ASSERT(!lkb->lkb_status, dlm_print_lkb(lkb);); +} + +/* __put_lkb() is used when an lkb may not have an rsb attached to + it so we need to provide the lockspace explicitly */ + +static int __put_lkb(struct dlm_ls *ls, struct dlm_lkb *lkb) +{ + uint16_t bucket = lkb->lkb_id & 0xFFFF; + + write_lock(&ls->ls_lkbtbl[bucket].lock); + if (kref_put(&lkb->lkb_ref, kill_lkb)) { + list_del(&lkb->lkb_idtbl_list); + write_unlock(&ls->ls_lkbtbl[bucket].lock); + + detach_lkb(lkb); + + /* for local/process lkbs, lvbptr points to caller's lksb */ + if (lkb->lkb_lvbptr && is_master_copy(lkb)) + free_lvb(lkb->lkb_lvbptr); + free_lkb(lkb); + return 1; + } else { + write_unlock(&ls->ls_lkbtbl[bucket].lock); + return 0; + } +} + +int dlm_put_lkb(struct dlm_lkb *lkb) +{ + struct dlm_ls *ls; + + DLM_ASSERT(lkb->lkb_resource, dlm_print_lkb(lkb);); + DLM_ASSERT(lkb->lkb_resource->res_ls, dlm_print_lkb(lkb);); + + ls = lkb->lkb_resource->res_ls; + return __put_lkb(ls, lkb); +} + +/* This is only called to add a reference when the code already holds + a valid reference to the lkb, so there's no need for locking. */ + +static inline void hold_lkb(struct dlm_lkb *lkb) +{ + kref_get(&lkb->lkb_ref); +} + +/* This is called when we need to remove a reference and are certain + it's not the last ref. e.g. del_lkb is always called between a + find_lkb/put_lkb and is always the inverse of a previous add_lkb. + put_lkb would work fine, but would involve unnecessary locking */ + +static inline void unhold_lkb(struct dlm_lkb *lkb) +{ + int rv; + rv = kref_put(&lkb->lkb_ref, kill_lkb); + DLM_ASSERT(!rv, dlm_print_lkb(lkb);); +} + +static void lkb_add_ordered(struct list_head *new, struct list_head *head, + int mode) +{ + struct dlm_lkb *lkb = NULL; + + list_for_each_entry(lkb, head, lkb_statequeue) + if (lkb->lkb_rqmode < mode) + break; + + if (!lkb) + list_add_tail(new, head); + else + __list_add(new, lkb->lkb_statequeue.prev, &lkb->lkb_statequeue); +} + +/* add/remove lkb to rsb's grant/convert/wait queue */ + +static void add_lkb(struct dlm_rsb *r, struct dlm_lkb *lkb, int status) +{ + kref_get(&lkb->lkb_ref); + + DLM_ASSERT(!lkb->lkb_status, dlm_print_lkb(lkb);); + + lkb->lkb_status = status; + + switch (status) { + case DLM_LKSTS_WAITING: + if (lkb->lkb_exflags & DLM_LKF_HEADQUE) + list_add(&lkb->lkb_statequeue, &r->res_waitqueue); + else + list_add_tail(&lkb->lkb_statequeue, &r->res_waitqueue); + break; + case DLM_LKSTS_GRANTED: + /* convention says granted locks kept in order of grmode */ + lkb_add_ordered(&lkb->lkb_statequeue, &r->res_grantqueue, + lkb->lkb_grmode); + break; + case DLM_LKSTS_CONVERT: + if (lkb->lkb_exflags & DLM_LKF_HEADQUE) + list_add(&lkb->lkb_statequeue, &r->res_convertqueue); + else + list_add_tail(&lkb->lkb_statequeue, + &r->res_convertqueue); + break; + default: + DLM_ASSERT(0, dlm_print_lkb(lkb); printk("sts=%d\n", status);); + } +} + +static void del_lkb(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + lkb->lkb_status = 0; + list_del(&lkb->lkb_statequeue); + unhold_lkb(lkb); +} + +static void move_lkb(struct dlm_rsb *r, struct dlm_lkb *lkb, int sts) +{ + hold_lkb(lkb); + del_lkb(r, lkb); + add_lkb(r, lkb, sts); + unhold_lkb(lkb); +} + +/* add/remove lkb from global waiters list of lkb's waiting for + a reply from a remote node */ + +static void add_to_waiters(struct dlm_lkb *lkb, int mstype) +{ + struct dlm_ls *ls = lkb->lkb_resource->res_ls; + + mutex_lock(&ls->ls_waiters_mutex); + if (lkb->lkb_wait_type) { + log_print("add_to_waiters error %d", lkb->lkb_wait_type); + goto out; + } + lkb->lkb_wait_type = mstype; + kref_get(&lkb->lkb_ref); + list_add(&lkb->lkb_wait_reply, &ls->ls_waiters); + out: + mutex_unlock(&ls->ls_waiters_mutex); +} + +static int _remove_from_waiters(struct dlm_lkb *lkb) +{ + int error = 0; + + if (!lkb->lkb_wait_type) { + log_print("remove_from_waiters error"); + error = -EINVAL; + goto out; + } + lkb->lkb_wait_type = 0; + list_del(&lkb->lkb_wait_reply); + unhold_lkb(lkb); + out: + return error; +} + +static int remove_from_waiters(struct dlm_lkb *lkb) +{ + struct dlm_ls *ls = lkb->lkb_resource->res_ls; + int error; + + mutex_lock(&ls->ls_waiters_mutex); + error = _remove_from_waiters(lkb); + mutex_unlock(&ls->ls_waiters_mutex); + return error; +} + +static void dir_remove(struct dlm_rsb *r) +{ + int to_nodeid; + + if (dlm_no_directory(r->res_ls)) + return; + + to_nodeid = dlm_dir_nodeid(r); + if (to_nodeid != dlm_our_nodeid()) + send_remove(r); + else + dlm_dir_remove_entry(r->res_ls, to_nodeid, + r->res_name, r->res_length); +} + +/* FIXME: shouldn't this be able to exit as soon as one non-due rsb is + found since they are in order of newest to oldest? */ + +static int shrink_bucket(struct dlm_ls *ls, int b) +{ + struct dlm_rsb *r; + int count = 0, found; + + for (;;) { + found = 0; + write_lock(&ls->ls_rsbtbl[b].lock); + list_for_each_entry_reverse(r, &ls->ls_rsbtbl[b].toss, + res_hashchain) { + if (!time_after_eq(jiffies, r->res_toss_time + + dlm_config.toss_secs * HZ)) + continue; + found = 1; + break; + } + + if (!found) { + write_unlock(&ls->ls_rsbtbl[b].lock); + break; + } + + if (kref_put(&r->res_ref, kill_rsb)) { + list_del(&r->res_hashchain); + write_unlock(&ls->ls_rsbtbl[b].lock); + + if (is_master(r)) + dir_remove(r); + free_rsb(r); + count++; + } else { + write_unlock(&ls->ls_rsbtbl[b].lock); + log_error(ls, "tossed rsb in use %s", r->res_name); + } + } + + return count; +} + +void dlm_scan_rsbs(struct dlm_ls *ls) +{ + int i; + + if (dlm_locking_stopped(ls)) + return; + + for (i = 0; i < ls->ls_rsbtbl_size; i++) { + shrink_bucket(ls, i); + cond_resched(); + } +} + +/* lkb is master or local copy */ + +static void set_lvb_lock(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + int b, len = r->res_ls->ls_lvblen; + + /* b=1 lvb returned to caller + b=0 lvb written to rsb or invalidated + b=-1 do nothing */ + + b = dlm_lvb_operations[lkb->lkb_grmode + 1][lkb->lkb_rqmode + 1]; + + if (b == 1) { + if (!lkb->lkb_lvbptr) + return; + + if (!(lkb->lkb_exflags & DLM_LKF_VALBLK)) + return; + + if (!r->res_lvbptr) + return; + + memcpy(lkb->lkb_lvbptr, r->res_lvbptr, len); + lkb->lkb_lvbseq = r->res_lvbseq; + + } else if (b == 0) { + if (lkb->lkb_exflags & DLM_LKF_IVVALBLK) { + rsb_set_flag(r, RSB_VALNOTVALID); + return; + } + + if (!lkb->lkb_lvbptr) + return; + + if (!(lkb->lkb_exflags & DLM_LKF_VALBLK)) + return; + + if (!r->res_lvbptr) + r->res_lvbptr = allocate_lvb(r->res_ls); + + if (!r->res_lvbptr) + return; + + memcpy(r->res_lvbptr, lkb->lkb_lvbptr, len); + r->res_lvbseq++; + lkb->lkb_lvbseq = r->res_lvbseq; + rsb_clear_flag(r, RSB_VALNOTVALID); + } + + if (rsb_flag(r, RSB_VALNOTVALID)) + lkb->lkb_sbflags |= DLM_SBF_VALNOTVALID; +} + +static void set_lvb_unlock(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + if (lkb->lkb_grmode < DLM_LOCK_PW) + return; + + if (lkb->lkb_exflags & DLM_LKF_IVVALBLK) { + rsb_set_flag(r, RSB_VALNOTVALID); + return; + } + + if (!lkb->lkb_lvbptr) + return; + + if (!(lkb->lkb_exflags & DLM_LKF_VALBLK)) + return; + + if (!r->res_lvbptr) + r->res_lvbptr = allocate_lvb(r->res_ls); + + if (!r->res_lvbptr) + return; + + memcpy(r->res_lvbptr, lkb->lkb_lvbptr, r->res_ls->ls_lvblen); + r->res_lvbseq++; + rsb_clear_flag(r, RSB_VALNOTVALID); +} + +/* lkb is process copy (pc) */ + +static void set_lvb_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb, + struct dlm_message *ms) +{ + int b; + + if (!lkb->lkb_lvbptr) + return; + + if (!(lkb->lkb_exflags & DLM_LKF_VALBLK)) + return; + + b = dlm_lvb_operations[lkb->lkb_grmode + 1][lkb->lkb_rqmode + 1]; + if (b == 1) { + int len = receive_extralen(ms); + memcpy(lkb->lkb_lvbptr, ms->m_extra, len); + lkb->lkb_lvbseq = ms->m_lvbseq; + } +} + +/* Manipulate lkb's on rsb's convert/granted/waiting queues + remove_lock -- used for unlock, removes lkb from granted + revert_lock -- used for cancel, moves lkb from convert to granted + grant_lock -- used for request and convert, adds lkb to granted or + moves lkb from convert or waiting to granted + + Each of these is used for master or local copy lkb's. There is + also a _pc() variation used to make the corresponding change on + a process copy (pc) lkb. */ + +static void _remove_lock(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + del_lkb(r, lkb); + lkb->lkb_grmode = DLM_LOCK_IV; + /* this unhold undoes the original ref from create_lkb() + so this leads to the lkb being freed */ + unhold_lkb(lkb); +} + +static void remove_lock(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + set_lvb_unlock(r, lkb); + _remove_lock(r, lkb); +} + +static void remove_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + _remove_lock(r, lkb); +} + +static void revert_lock(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + lkb->lkb_rqmode = DLM_LOCK_IV; + + switch (lkb->lkb_status) { + case DLM_LKSTS_GRANTED: + break; + case DLM_LKSTS_CONVERT: + move_lkb(r, lkb, DLM_LKSTS_GRANTED); + break; + case DLM_LKSTS_WAITING: + del_lkb(r, lkb); + lkb->lkb_grmode = DLM_LOCK_IV; + /* this unhold undoes the original ref from create_lkb() + so this leads to the lkb being freed */ + unhold_lkb(lkb); + break; + default: + log_print("invalid status for revert %d", lkb->lkb_status); + } +} + +static void revert_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + revert_lock(r, lkb); +} + +static void _grant_lock(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + if (lkb->lkb_grmode != lkb->lkb_rqmode) { + lkb->lkb_grmode = lkb->lkb_rqmode; + if (lkb->lkb_status) + move_lkb(r, lkb, DLM_LKSTS_GRANTED); + else + add_lkb(r, lkb, DLM_LKSTS_GRANTED); + } + + lkb->lkb_rqmode = DLM_LOCK_IV; +} + +static void grant_lock(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + set_lvb_lock(r, lkb); + _grant_lock(r, lkb); + lkb->lkb_highbast = 0; +} + +static void grant_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb, + struct dlm_message *ms) +{ + set_lvb_lock_pc(r, lkb, ms); + _grant_lock(r, lkb); +} + +/* called by grant_pending_locks() which means an async grant message must + be sent to the requesting node in addition to granting the lock if the + lkb belongs to a remote node. */ + +static void grant_lock_pending(struct dlm_rsb *r, struct dlm_lkb *lkb) +{ + grant_lock(r, lkb); + if (is_master_copy(lkb)) + send_grant(r, lkb); + else + queue_cast(r, lkb, 0); +} + +static inline int first_in_list(struct dlm_lkb *lkb, struct list_head *head) +{ + struct dlm_lkb *first = list_entry(head->next, struct dlm_lkb, + lkb_statequeue); + if (lkb->lkb_id == first->lkb_id) + return 1; + + return 0; +} + +/* Check if the given lkb conflicts with another lkb on the queue. */ + +static int queue_conflict(struct list_head *head, struct dlm_lkb *lkb) +{ + struct dlm_lkb *this; + + list_for_each_entry(this, head, lkb_statequeue) { + if (this == lkb) + continue; + if (!modes_compat(this, lkb)) + return 1; + } + return 0; +} + +/* + * "A conversion deadlock arises with a pair of lock requests in the converting + * queue for one resource. The granted mode of each lock blocks the requested + * mode of the other lock." + * + * Part 2: if the granted mode of lkb is preventing the first lkb in the + * convert queue from being granted, then demote lkb (set grmode to NL). + * This second form requires that we check for conv-deadlk even when + * now == 0 in _can_be_granted(). + * + * Example: + * Granted Queue: empty + * Convert Queue: NL->EX (first lock) + * PR->EX (second lock) + * + * The first lock can't be granted because of the granted mode of the second + * lock and the second lock can't be granted because it's not first in the + * list. We demote the granted mode of the second lock (the lkb passed to this + * function). + * + * After the resolution, the "grant pending" function needs to go back and try + * to grant locks on the convert queue again since the first lock can now be + * granted. + */ + +static int conversion_deadlock_detect(struct dlm_rsb *rsb, struct dlm_lkb *lkb) +{ + struct dlm_lkb *this, *first = NULL, *self = NULL; + + list_for_each_entry(this, &rsb->res_convertqueue, lkb_statequeue) { + if (!first) + first = this; + if (this == lkb) { + self = lkb; + continue; + } + + if (!modes_compat(this, lkb) && !modes_compat(lkb, this)) + return 1; + } + + /* if lkb is on the convert queue and is preventing the first + from being granted, then there's deadlock and we demote lkb. + multiple converting locks may need to do this before the first + converting lock can be granted. */ + + if (self && self != first) { + if (!modes_compat(lkb, first) && + !queue_conflict(&rsb->res_grantqueue, first)) + return 1; + } + + return 0; +} + +/* + * Return 1 if the lock can be granted, 0 otherwise. + * Also detect and resolve conversion deadlocks. + * + * lkb is the lock to be granted + * + * now is 1 if the function is being called in the context of the + * immediate request, it is 0 if called later, after the lock has been + * queued. + * + * References are from chapter 6 of "VAXcluster Principles" by Roy Davis + */ + +static int _can_be_granted(struct dlm_rsb *r, struct dlm_lkb *lkb, int now) +{ + int8_t conv = (lkb->lkb_grmode != DLM_LOCK_IV); + + /* + * 6-10: Version 5.4 introduced an option to address the phenomenon of + * a new request for a NL mode lock being blocked. + * + * 6-11: If the optional EXPEDITE flag is used with the new NL mode + * request, then it would be granted. In essence, the use of this flag + * tells the Lock Manager to expedite theis request by not considering + * what may be in the CONVERTING or WAITING queues... As of this + * writing, the EXPEDITE flag can be used only with new requests for NL + * mode locks. This flag is not valid for conversion requests. + * + * A shortcut. Earlier checks return an error if EXPEDITE is used in a + * conversion or used with a non-NL requested mode. We also know an + * EXPEDITE request is always granted immediately, so now must always + * be 1. The full condition to grant an expedite request: (now && + * !conv && lkb->rqmode == DLM_LOCK_NL && (flags & EXPEDITE)) can + * therefore be shortened to just checking the flag. + */ + + if (lkb->lkb_exflags & DLM_LKF_EXPEDITE) + return 1; + + /* + * A shortcut. Without this, !queue_conflict(grantqueue, lkb) would be + * added to the remaining conditions. + */ + + if (queue_conflict(&r->res_grantqueue, lkb)) + goto out; + + /* + * 6-3: By default, a conversion request is immediately granted if the + * requested mode is compatible with the modes of all other granted + * locks + */ + + if (queue_conflict(&r->res_convertqueue, lkb)) + goto out; + + /* + * 6-5: But the default algorithm for deciding whether to grant or + * queue conversion requests does not by itself guarantee that such + * requests are serviced on a "first come first serve" basis. This, in |