diff options
Diffstat (limited to 'fs/dlm/plock.c')
| -rw-r--r-- | fs/dlm/plock.c | 537 |
1 files changed, 537 insertions, 0 deletions
diff --git a/fs/dlm/plock.c b/fs/dlm/plock.c new file mode 100644 index 000000000..1bf5c51a4 --- /dev/null +++ b/fs/dlm/plock.c @@ -0,0 +1,537 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved. + */ + +#include <linux/fs.h> +#include <linux/miscdevice.h> +#include <linux/poll.h> +#include <linux/dlm.h> +#include <linux/dlm_plock.h> +#include <linux/slab.h> + +#include "dlm_internal.h" +#include "lockspace.h" + +static DEFINE_SPINLOCK(ops_lock); +static LIST_HEAD(send_list); +static LIST_HEAD(recv_list); +static DECLARE_WAIT_QUEUE_HEAD(send_wq); +static DECLARE_WAIT_QUEUE_HEAD(recv_wq); + +struct plock_async_data { + void *fl; + void *file; + struct file_lock flc; + int (*callback)(struct file_lock *fl, int result); +}; + +struct plock_op { + struct list_head list; + int done; + struct dlm_plock_info info; + /* if set indicates async handling */ + struct plock_async_data *data; +}; + +static inline void set_version(struct dlm_plock_info *info) +{ + info->version[0] = DLM_PLOCK_VERSION_MAJOR; + info->version[1] = DLM_PLOCK_VERSION_MINOR; + info->version[2] = DLM_PLOCK_VERSION_PATCH; +} + +static int check_version(struct dlm_plock_info *info) +{ + if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) || + (DLM_PLOCK_VERSION_MINOR < info->version[1])) { + log_print("plock device version mismatch: " + "kernel (%u.%u.%u), user (%u.%u.%u)", + DLM_PLOCK_VERSION_MAJOR, + DLM_PLOCK_VERSION_MINOR, + DLM_PLOCK_VERSION_PATCH, + info->version[0], + info->version[1], + info->version[2]); + return -EINVAL; + } + return 0; +} + +static void dlm_release_plock_op(struct plock_op *op) +{ + kfree(op->data); + kfree(op); +} + +static void send_op(struct plock_op *op) +{ + set_version(&op->info); + spin_lock(&ops_lock); + list_add_tail(&op->list, &send_list); + spin_unlock(&ops_lock); + wake_up(&send_wq); +} + +/* If a process was killed while waiting for the only plock on a file, + locks_remove_posix will not see any lock on the file so it won't + send an unlock-close to us to pass on to userspace to clean up the + abandoned waiter. So, we have to insert the unlock-close when the + lock call is interrupted. */ + +static void do_unlock_close(const struct dlm_plock_info *info) +{ + struct plock_op *op; + + op = kzalloc(sizeof(*op), GFP_NOFS); + if (!op) + return; + + op->info.optype = DLM_PLOCK_OP_UNLOCK; + op->info.pid = info->pid; + op->info.fsid = info->fsid; + op->info.number = info->number; + op->info.start = 0; + op->info.end = OFFSET_MAX; + op->info.owner = info->owner; + + op->info.flags |= DLM_PLOCK_FL_CLOSE; + send_op(op); +} + +int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file, + int cmd, struct file_lock *fl) +{ + struct plock_async_data *op_data; + struct dlm_ls *ls; + struct plock_op *op; + int rv; + + ls = dlm_find_lockspace_local(lockspace); + if (!ls) + return -EINVAL; + + op = kzalloc(sizeof(*op), GFP_NOFS); + if (!op) { + rv = -ENOMEM; + goto out; + } + + op->info.optype = DLM_PLOCK_OP_LOCK; + op->info.pid = fl->fl_pid; + op->info.ex = (fl->fl_type == F_WRLCK); + op->info.wait = IS_SETLKW(cmd); + op->info.fsid = ls->ls_global_id; + op->info.number = number; + op->info.start = fl->fl_start; + op->info.end = fl->fl_end; + /* async handling */ + if (fl->fl_lmops && fl->fl_lmops->lm_grant) { + op_data = kzalloc(sizeof(*op_data), GFP_NOFS); + if (!op_data) { + dlm_release_plock_op(op); + rv = -ENOMEM; + goto out; + } + + /* fl_owner is lockd which doesn't distinguish + processes on the nfs client */ + op->info.owner = (__u64) fl->fl_pid; + op_data->callback = fl->fl_lmops->lm_grant; + locks_init_lock(&op_data->flc); + locks_copy_lock(&op_data->flc, fl); + op_data->fl = fl; + op_data->file = file; + + op->data = op_data; + + send_op(op); + rv = FILE_LOCK_DEFERRED; + goto out; + } else { + op->info.owner = (__u64)(long) fl->fl_owner; + } + + send_op(op); + + if (op->info.wait) { + rv = wait_event_killable(recv_wq, (op->done != 0)); + if (rv == -ERESTARTSYS) { + spin_lock(&ops_lock); + /* recheck under ops_lock if we got a done != 0, + * if so this interrupt case should be ignored + */ + if (op->done != 0) { + spin_unlock(&ops_lock); + goto do_lock_wait; + } + list_del(&op->list); + spin_unlock(&ops_lock); + + log_debug(ls, "%s: wait interrupted %x %llx pid %d", + __func__, ls->ls_global_id, + (unsigned long long)number, op->info.pid); + do_unlock_close(&op->info); + dlm_release_plock_op(op); + goto out; + } + } else { + wait_event(recv_wq, (op->done != 0)); + } + +do_lock_wait: + + WARN_ON(!list_empty(&op->list)); + + rv = op->info.rv; + + if (!rv) { + if (locks_lock_file_wait(file, fl) < 0) + log_error(ls, "dlm_posix_lock: vfs lock error %llx", + (unsigned long long)number); + } + + dlm_release_plock_op(op); +out: + dlm_put_lockspace(ls); + return rv; +} +EXPORT_SYMBOL_GPL(dlm_posix_lock); + +/* Returns failure iff a successful lock operation should be canceled */ +static int dlm_plock_callback(struct plock_op *op) +{ + struct plock_async_data *op_data = op->data; + struct file *file; + struct file_lock *fl; + struct file_lock *flc; + int (*notify)(struct file_lock *fl, int result) = NULL; + int rv = 0; + + WARN_ON(!list_empty(&op->list)); + + /* check if the following 2 are still valid or make a copy */ + file = op_data->file; + flc = &op_data->flc; + fl = op_data->fl; + notify = op_data->callback; + + if (op->info.rv) { + notify(fl, op->info.rv); + goto out; + } + + /* got fs lock; bookkeep locally as well: */ + flc->fl_flags &= ~FL_SLEEP; + if (posix_lock_file(file, flc, NULL)) { + /* + * This can only happen in the case of kmalloc() failure. + * The filesystem's own lock is the authoritative lock, + * so a failure to get the lock locally is not a disaster. + * As long as the fs cannot reliably cancel locks (especially + * in a low-memory situation), we're better off ignoring + * this failure than trying to recover. + */ + log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p", + (unsigned long long)op->info.number, file, fl); + } + + rv = notify(fl, 0); + if (rv) { + /* XXX: We need to cancel the fs lock here: */ + log_print("dlm_plock_callback: lock granted after lock request " + "failed; dangling lock!\n"); + goto out; + } + +out: + dlm_release_plock_op(op); + return rv; +} + +int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file, + struct file_lock *fl) +{ + struct dlm_ls *ls; + struct plock_op *op; + int rv; + unsigned char fl_flags = fl->fl_flags; + + ls = dlm_find_lockspace_local(lockspace); + if (!ls) + return -EINVAL; + + op = kzalloc(sizeof(*op), GFP_NOFS); + if (!op) { + rv = -ENOMEM; + goto out; + } + + /* cause the vfs unlock to return ENOENT if lock is not found */ + fl->fl_flags |= FL_EXISTS; + + rv = locks_lock_file_wait(file, fl); + if (rv == -ENOENT) { + rv = 0; + goto out_free; + } + if (rv < 0) { + log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx", + rv, (unsigned long long)number); + } + + op->info.optype = DLM_PLOCK_OP_UNLOCK; + op->info.pid = fl->fl_pid; + op->info.fsid = ls->ls_global_id; + op->info.number = number; + op->info.start = fl->fl_start; + op->info.end = fl->fl_end; + if (fl->fl_lmops && fl->fl_lmops->lm_grant) + op->info.owner = (__u64) fl->fl_pid; + else + op->info.owner = (__u64)(long) fl->fl_owner; + + if (fl->fl_flags & FL_CLOSE) { + op->info.flags |= DLM_PLOCK_FL_CLOSE; + send_op(op); + rv = 0; + goto out; + } + + send_op(op); + wait_event(recv_wq, (op->done != 0)); + + WARN_ON(!list_empty(&op->list)); + + rv = op->info.rv; + + if (rv == -ENOENT) + rv = 0; + +out_free: + dlm_release_plock_op(op); +out: + dlm_put_lockspace(ls); + fl->fl_flags = fl_flags; + return rv; +} +EXPORT_SYMBOL_GPL(dlm_posix_unlock); + +int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file, + struct file_lock *fl) +{ + struct dlm_ls *ls; + struct plock_op *op; + int rv; + + ls = dlm_find_lockspace_local(lockspace); + if (!ls) + return -EINVAL; + + op = kzalloc(sizeof(*op), GFP_NOFS); + if (!op) { + rv = -ENOMEM; + goto out; + } + + op->info.optype = DLM_PLOCK_OP_GET; + op->info.pid = fl->fl_pid; + op->info.ex = (fl->fl_type == F_WRLCK); + op->info.fsid = ls->ls_global_id; + op->info.number = number; + op->info.start = fl->fl_start; + op->info.end = fl->fl_end; + if (fl->fl_lmops && fl->fl_lmops->lm_grant) + op->info.owner = (__u64) fl->fl_pid; + else + op->info.owner = (__u64)(long) fl->fl_owner; + + send_op(op); + wait_event(recv_wq, (op->done != 0)); + + WARN_ON(!list_empty(&op->list)); + + /* info.rv from userspace is 1 for conflict, 0 for no-conflict, + -ENOENT if there are no locks on the file */ + + rv = op->info.rv; + + fl->fl_type = F_UNLCK; + if (rv == -ENOENT) + rv = 0; + else if (rv > 0) { + locks_init_lock(fl); + fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK; + fl->fl_flags = FL_POSIX; + fl->fl_pid = op->info.pid; + if (op->info.nodeid != dlm_our_nodeid()) + fl->fl_pid = -fl->fl_pid; + fl->fl_start = op->info.start; + fl->fl_end = op->info.end; + rv = 0; + } + + dlm_release_plock_op(op); +out: + dlm_put_lockspace(ls); + return rv; +} +EXPORT_SYMBOL_GPL(dlm_posix_get); + +/* a read copies out one plock request from the send list */ +static ssize_t dev_read(struct file *file, char __user *u, size_t count, + loff_t *ppos) +{ + struct dlm_plock_info info; + struct plock_op *op = NULL; + + if (count < sizeof(info)) + return -EINVAL; + + spin_lock(&ops_lock); + if (!list_empty(&send_list)) { + op = list_first_entry(&send_list, struct plock_op, list); + if (op->info.flags & DLM_PLOCK_FL_CLOSE) + list_del(&op->list); + else + list_move_tail(&op->list, &recv_list); + memcpy(&info, &op->info, sizeof(info)); + } + spin_unlock(&ops_lock); + + if (!op) + return -EAGAIN; + + /* there is no need to get a reply from userspace for unlocks + that were generated by the vfs cleaning up for a close + (the process did not make an unlock call). */ + + if (op->info.flags & DLM_PLOCK_FL_CLOSE) + dlm_release_plock_op(op); + + if (copy_to_user(u, &info, sizeof(info))) + return -EFAULT; + return sizeof(info); +} + +/* a write copies in one plock result that should match a plock_op + on the recv list */ +static ssize_t dev_write(struct file *file, const char __user *u, size_t count, + loff_t *ppos) +{ + struct plock_op *op = NULL, *iter; + struct dlm_plock_info info; + int do_callback = 0; + + if (count != sizeof(info)) + return -EINVAL; + + if (copy_from_user(&info, u, sizeof(info))) + return -EFAULT; + + if (check_version(&info)) + return -EINVAL; + + /* + * The results for waiting ops (SETLKW) can be returned in any + * order, so match all fields to find the op. The results for + * non-waiting ops are returned in the order that they were sent + * to userspace, so match the result with the first non-waiting op. + */ + spin_lock(&ops_lock); + if (info.wait) { + list_for_each_entry(iter, &recv_list, list) { + if (iter->info.fsid == info.fsid && + iter->info.number == info.number && + iter->info.owner == info.owner && + iter->info.pid == info.pid && + iter->info.start == info.start && + iter->info.end == info.end && + iter->info.ex == info.ex && + iter->info.wait) { + op = iter; + break; + } + } + } else { + list_for_each_entry(iter, &recv_list, list) { + if (!iter->info.wait && + iter->info.fsid == info.fsid) { + op = iter; + break; + } + } + } + + if (op) { + /* Sanity check that op and info match. */ + if (info.wait) + WARN_ON(op->info.optype != DLM_PLOCK_OP_LOCK); + else + WARN_ON(op->info.number != info.number || + op->info.owner != info.owner || + op->info.optype != info.optype); + + list_del_init(&op->list); + memcpy(&op->info, &info, sizeof(info)); + if (op->data) + do_callback = 1; + else + op->done = 1; + } + spin_unlock(&ops_lock); + + if (op) { + if (do_callback) + dlm_plock_callback(op); + else + wake_up(&recv_wq); + } else + pr_debug("%s: no op %x %llx", __func__, + info.fsid, (unsigned long long)info.number); + return count; +} + +static __poll_t dev_poll(struct file *file, poll_table *wait) +{ + __poll_t mask = 0; + + poll_wait(file, &send_wq, wait); + + spin_lock(&ops_lock); + if (!list_empty(&send_list)) + mask = EPOLLIN | EPOLLRDNORM; + spin_unlock(&ops_lock); + + return mask; +} + +static const struct file_operations dev_fops = { + .read = dev_read, + .write = dev_write, + .poll = dev_poll, + .owner = THIS_MODULE, + .llseek = noop_llseek, +}; + +static struct miscdevice plock_dev_misc = { + .minor = MISC_DYNAMIC_MINOR, + .name = DLM_PLOCK_MISC_NAME, + .fops = &dev_fops +}; + +int dlm_plock_init(void) +{ + int rv; + + rv = misc_register(&plock_dev_misc); + if (rv) + log_print("dlm_plock_init: misc_register failed %d", rv); + return rv; +} + +void dlm_plock_exit(void) +{ + misc_deregister(&plock_dev_misc); +} + |