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-rw-r--r--fs/dlm/plock.c537
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);
+}
+
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