Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0
/*
 * linux/fs/lockd/svclock.c
 *
 * Handling of server-side locks, mostly of the blocked variety.
 * This is the ugliest part of lockd because we tread on very thin ice.
 * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
 * IMNSHO introducing the grant callback into the NLM protocol was one
 * of the worst ideas Sun ever had. Except maybe for the idea of doing
 * NFS file locking at all.
 *
 * I'm trying hard to avoid race conditions by protecting most accesses
 * to a file's list of blocked locks through a semaphore. The global
 * list of blocked locks is not protected in this fashion however.
 * Therefore, some functions (such as the RPC callback for the async grant
 * call) move blocked locks towards the head of the list *while some other
 * process might be traversing it*. This should not be a problem in
 * practice, because this will only cause functions traversing the list
 * to visit some blocks twice.
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */
 
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc_xprt.h>
#include <linux/lockd/nlm.h>
#include <linux/lockd/lockd.h>
#include <linux/kthread.h>
 
#define NLMDBG_FACILITY		NLMDBG_SVCLOCK
 
#ifdef CONFIG_LOCKD_V4
#define nlm_deadlock	nlm4_deadlock
#else
#define nlm_deadlock	nlm_lck_denied
#endif
 
static void nlmsvc_release_block(struct nlm_block *block);
static void	nlmsvc_insert_block(struct nlm_block *block, unsigned long);
static void	nlmsvc_remove_block(struct nlm_block *block);
 
static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
static void nlmsvc_freegrantargs(struct nlm_rqst *call);
static const struct rpc_call_ops nlmsvc_grant_ops;
 
/*
 * The list of blocked locks to retry
 */
static LIST_HEAD(nlm_blocked);
static DEFINE_SPINLOCK(nlm_blocked_lock);
 
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
{
<------>/*
<------> * We can get away with a static buffer because this is only called
<------> * from lockd, which is single-threaded.
<------> */
<------>static char buf[2*NLM_MAXCOOKIELEN+1];
<------>unsigned int i, len = sizeof(buf);
<------>char *p = buf;
 
<------>len--;	/* allow for trailing \0 */
<------>if (len < 3)
<------><------>return "???";
<------>for (i = 0 ; i < cookie->len ; i++) {
<------><------>if (len < 2) {
<------><------><------>strcpy(p-3, "...");
<------><------><------>break;
<------><------>}
<------><------>sprintf(p, "%02x", cookie->data[i]);
<------><------>p += 2;
<------><------>len -= 2;
<------>}
<------>*p = '\0';
 
<------>return buf;
}
#endif
 
/*
 * Insert a blocked lock into the global list
 */
static void
nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
{
<------>struct nlm_block *b;
<------>struct list_head *pos;
 
<------>dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
<------>if (list_empty(&block->b_list)) {
<------><------>kref_get(&block->b_count);
<------>} else {
<------><------>list_del_init(&block->b_list);
<------>}
 
<------>pos = &nlm_blocked;
<------>if (when != NLM_NEVER) {
<------><------>if ((when += jiffies) == NLM_NEVER)
<------><------><------>when ++;
<------><------>list_for_each(pos, &nlm_blocked) {
<------><------><------>b = list_entry(pos, struct nlm_block, b_list);
<------><------><------>if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
<------><------><------><------>break;
<------><------>}
<------><------>/* On normal exit from the loop, pos == &nlm_blocked,
<------><------> * so we will be adding to the end of the list - good
<------><------> */
<------>}
 
<------>list_add_tail(&block->b_list, pos);
<------>block->b_when = when;
}
 
static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
{
<------>spin_lock(&nlm_blocked_lock);
<------>nlmsvc_insert_block_locked(block, when);
<------>spin_unlock(&nlm_blocked_lock);
}
 
/*
 * Remove a block from the global list
 */
static inline void
nlmsvc_remove_block(struct nlm_block *block)
{
<------>if (!list_empty(&block->b_list)) {
<------><------>spin_lock(&nlm_blocked_lock);
<------><------>list_del_init(&block->b_list);
<------><------>spin_unlock(&nlm_blocked_lock);
<------><------>nlmsvc_release_block(block);
<------>}
}
 
/*
 * Find a block for a given lock
 */
static struct nlm_block *
nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
{
<------>struct nlm_block	*block;
<------>struct file_lock	*fl;
 
<------>dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
<------><------><------><------>file, lock->fl.fl_pid,
<------><------><------><------>(long long)lock->fl.fl_start,
<------><------><------><------>(long long)lock->fl.fl_end, lock->fl.fl_type);
<------>list_for_each_entry(block, &nlm_blocked, b_list) {
<------><------>fl = &block->b_call->a_args.lock.fl;
<------><------>dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
<------><------><------><------>block->b_file, fl->fl_pid,
<------><------><------><------>(long long)fl->fl_start,
<------><------><------><------>(long long)fl->fl_end, fl->fl_type,
<------><------><------><------>nlmdbg_cookie2a(&block->b_call->a_args.cookie));
<------><------>if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
<------><------><------>kref_get(&block->b_count);
<------><------><------>return block;
<------><------>}
<------>}
 
<------>return NULL;
}
 
static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
{
<------>if (a->len != b->len)
<------><------>return 0;
<------>if (memcmp(a->data, b->data, a->len))
<------><------>return 0;
<------>return 1;
}
 
/*
 * Find a block with a given NLM cookie.
 */
static inline struct nlm_block *
nlmsvc_find_block(struct nlm_cookie *cookie)
{
<------>struct nlm_block *block;
 
<------>list_for_each_entry(block, &nlm_blocked, b_list) {
<------><------>if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
<------><------><------>goto found;
<------>}
 
<------>return NULL;
 
found:
<------>dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
<------>kref_get(&block->b_count);
<------>return block;
}
 
/*
 * Create a block and initialize it.
 *
 * Note: we explicitly set the cookie of the grant reply to that of
 * the blocked lock request. The spec explicitly mentions that the client
 * should _not_ rely on the callback containing the same cookie as the
 * request, but (as I found out later) that's because some implementations
 * do just this. Never mind the standards comittees, they support our
 * logging industries.
 *
 * 10 years later: I hope we can safely ignore these old and broken
 * clients by now. Let's fix this so we can uniquely identify an incoming
 * GRANTED_RES message by cookie, without having to rely on the client's IP
 * address. --okir
 */
static struct nlm_block *
nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
<------><------>    struct nlm_file *file, struct nlm_lock *lock,
<------><------>    struct nlm_cookie *cookie)
{
<------>struct nlm_block	*block;
<------>struct nlm_rqst		*call = NULL;
 
<------>call = nlm_alloc_call(host);
<------>if (call == NULL)
<------><------>return NULL;
 
<------>/* Allocate memory for block, and initialize arguments */
<------>block = kzalloc(sizeof(*block), GFP_KERNEL);
<------>if (block == NULL)
<------><------>goto failed;
<------>kref_init(&block->b_count);
<------>INIT_LIST_HEAD(&block->b_list);
<------>INIT_LIST_HEAD(&block->b_flist);
 
<------>if (!nlmsvc_setgrantargs(call, lock))
<------><------>goto failed_free;
 
<------>/* Set notifier function for VFS, and init args */
<------>call->a_args.lock.fl.fl_flags |= FL_SLEEP;
<------>call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
<------>nlmclnt_next_cookie(&call->a_args.cookie);
 
<------>dprintk("lockd: created block %p...\n", block);
 
<------>/* Create and initialize the block */
<------>block->b_daemon = rqstp->rq_server;
<------>block->b_host   = host;
<------>block->b_file   = file;
<------>file->f_count++;
 
<------>/* Add to file's list of blocks */
<------>list_add(&block->b_flist, &file->f_blocks);
 
<------>/* Set up RPC arguments for callback */
<------>block->b_call = call;
<------>call->a_flags   = RPC_TASK_ASYNC;
<------>call->a_block = block;
 
<------>return block;
 
failed_free:
<------>kfree(block);
failed:
<------>nlmsvc_release_call(call);
<------>return NULL;
}
 
/*
 * Delete a block.
 * It is the caller's responsibility to check whether the file
 * can be closed hereafter.
 */
static int nlmsvc_unlink_block(struct nlm_block *block)
{
<------>int status;
<------>dprintk("lockd: unlinking block %p...\n", block);
 
<------>/* Remove block from list */
<------>status = locks_delete_block(&block->b_call->a_args.lock.fl);
<------>nlmsvc_remove_block(block);
<------>return status;
}
 
static void nlmsvc_free_block(struct kref *kref)
{
<------>struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
<------>struct nlm_file		*file = block->b_file;
 
<------>dprintk("lockd: freeing block %p...\n", block);
 
<------>/* Remove block from file's list of blocks */
<------>list_del_init(&block->b_flist);
<------>mutex_unlock(&file->f_mutex);
 
<------>nlmsvc_freegrantargs(block->b_call);
<------>nlmsvc_release_call(block->b_call);
<------>nlm_release_file(block->b_file);
<------>kfree(block);
}
 
static void nlmsvc_release_block(struct nlm_block *block)
{
<------>if (block != NULL)
<------><------>kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
}
 
/*
 * Loop over all blocks and delete blocks held by
 * a matching host.
 */
void nlmsvc_traverse_blocks(struct nlm_host *host,
<------><------><------>struct nlm_file *file,
<------><------><------>nlm_host_match_fn_t match)
{
<------>struct nlm_block *block, *next;
 
restart:
<------>mutex_lock(&file->f_mutex);
<------>list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
<------><------>if (!match(block->b_host, host))
<------><------><------>continue;
<------><------>/* Do not destroy blocks that are not on
<------><------> * the global retry list - why? */
<------><------>if (list_empty(&block->b_list))
<------><------><------>continue;
<------><------>kref_get(&block->b_count);
<------><------>mutex_unlock(&file->f_mutex);
<------><------>nlmsvc_unlink_block(block);
<------><------>nlmsvc_release_block(block);
<------><------>goto restart;
<------>}
<------>mutex_unlock(&file->f_mutex);
}
 
static struct nlm_lockowner *
nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
{
<------>refcount_inc(&lockowner->count);
<------>return lockowner;
}
 
static void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
{
<------>if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
<------><------>return;
<------>list_del(&lockowner->list);
<------>spin_unlock(&lockowner->host->h_lock);
<------>nlmsvc_release_host(lockowner->host);
<------>kfree(lockowner);
}
 
static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
{
<------>struct nlm_lockowner *lockowner;
<------>list_for_each_entry(lockowner, &host->h_lockowners, list) {
<------><------>if (lockowner->pid != pid)
<------><------><------>continue;
<------><------>return nlmsvc_get_lockowner(lockowner);
<------>}
<------>return NULL;
}
 
static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
{
<------>struct nlm_lockowner *res, *new = NULL;
 
<------>spin_lock(&host->h_lock);
<------>res = __nlmsvc_find_lockowner(host, pid);
 
<------>if (res == NULL) {
<------><------>spin_unlock(&host->h_lock);
<------><------>new = kmalloc(sizeof(*res), GFP_KERNEL);
<------><------>spin_lock(&host->h_lock);
<------><------>res = __nlmsvc_find_lockowner(host, pid);
<------><------>if (res == NULL && new != NULL) {
<------><------><------>res = new;
<------><------><------>/* fs/locks.c will manage the refcount through lock_ops */
<------><------><------>refcount_set(&new->count, 1);
<------><------><------>new->pid = pid;
<------><------><------>new->host = nlm_get_host(host);
<------><------><------>list_add(&new->list, &host->h_lockowners);
<------><------><------>new = NULL;
<------><------>}
<------>}
 
<------>spin_unlock(&host->h_lock);
<------>kfree(new);
<------>return res;
}
 
void
nlmsvc_release_lockowner(struct nlm_lock *lock)
{
<------>if (lock->fl.fl_owner)
<------><------>nlmsvc_put_lockowner(lock->fl.fl_owner);
}
 
void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
<------><------><------><------><------><------>pid_t pid)
{
<------>fl->fl_owner = nlmsvc_find_lockowner(host, pid);
}
 
/*
 * Initialize arguments for GRANTED call. The nlm_rqst structure
 * has been cleared already.
 */
static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
{
<------>locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
<------>memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
<------>call->a_args.lock.caller = utsname()->nodename;
<------>call->a_args.lock.oh.len = lock->oh.len;
 
<------>/* set default data area */
<------>call->a_args.lock.oh.data = call->a_owner;
<------>call->a_args.lock.svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
 
<------>if (lock->oh.len > NLMCLNT_OHSIZE) {
<------><------>void *data = kmalloc(lock->oh.len, GFP_KERNEL);
<------><------>if (!data)
<------><------><------>return 0;
<------><------>call->a_args.lock.oh.data = (u8 *) data;
<------>}
 
<------>memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
<------>return 1;
}
 
static void nlmsvc_freegrantargs(struct nlm_rqst *call)
{
<------>if (call->a_args.lock.oh.data != call->a_owner)
<------><------>kfree(call->a_args.lock.oh.data);
 
<------>locks_release_private(&call->a_args.lock.fl);
}
 
/*
 * Deferred lock request handling for non-blocking lock
 */
static __be32
nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
{
<------>__be32 status = nlm_lck_denied_nolocks;
 
<------>block->b_flags |= B_QUEUED;
 
<------>nlmsvc_insert_block(block, NLM_TIMEOUT);
 
<------>block->b_cache_req = &rqstp->rq_chandle;
<------>if (rqstp->rq_chandle.defer) {
<------><------>block->b_deferred_req =
<------><------><------>rqstp->rq_chandle.defer(block->b_cache_req);
<------><------>if (block->b_deferred_req != NULL)
<------><------><------>status = nlm_drop_reply;
<------>}
<------>dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
<------><------>block, block->b_flags, ntohl(status));
 
<------>return status;
}
 
/*
 * Attempt to establish a lock, and if it can't be granted, block it
 * if required.
 */
__be32
nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
<------>    struct nlm_host *host, struct nlm_lock *lock, int wait,
<------>    struct nlm_cookie *cookie, int reclaim)
{
<------>struct nlm_block	*block = NULL;
<------>int			error;
<------>__be32			ret;
 
<------>dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
<------><------><------><------>locks_inode(file->f_file)->i_sb->s_id,
<------><------><------><------>locks_inode(file->f_file)->i_ino,
<------><------><------><------>lock->fl.fl_type, lock->fl.fl_pid,
<------><------><------><------>(long long)lock->fl.fl_start,
<------><------><------><------>(long long)lock->fl.fl_end,
<------><------><------><------>wait);
 
<------>/* Lock file against concurrent access */
<------>mutex_lock(&file->f_mutex);
<------>/* Get existing block (in case client is busy-waiting)
<------> * or create new block
<------> */
<------>block = nlmsvc_lookup_block(file, lock);
<------>if (block == NULL) {
<------><------>block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
<------><------>ret = nlm_lck_denied_nolocks;
<------><------>if (block == NULL)
<------><------><------>goto out;
<------><------>lock = &block->b_call->a_args.lock;
<------>} else
<------><------>lock->fl.fl_flags &= ~FL_SLEEP;
 
<------>if (block->b_flags & B_QUEUED) {
<------><------>dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
<------><------><------><------><------><------><------>block, block->b_flags);
<------><------>if (block->b_granted) {
<------><------><------>nlmsvc_unlink_block(block);
<------><------><------>ret = nlm_granted;
<------><------><------>goto out;
<------><------>}
<------><------>if (block->b_flags & B_TIMED_OUT) {
<------><------><------>nlmsvc_unlink_block(block);
<------><------><------>ret = nlm_lck_denied;
<------><------><------>goto out;
<------><------>}
<------><------>ret = nlm_drop_reply;
<------><------>goto out;
<------>}
 
<------>if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
<------><------>ret = nlm_lck_denied_grace_period;
<------><------>goto out;
<------>}
<------>if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
<------><------>ret = nlm_lck_denied_grace_period;
<------><------>goto out;
<------>}
 
<------>if (!wait)
<------><------>lock->fl.fl_flags &= ~FL_SLEEP;
<------>error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
<------>lock->fl.fl_flags &= ~FL_SLEEP;
 
<------>dprintk("lockd: vfs_lock_file returned %d\n", error);
<------>switch (error) {
<------><------>case 0:
<------><------><------>ret = nlm_granted;
<------><------><------>goto out;
<------><------>case -EAGAIN:
<------><------><------>/*
<------><------><------> * If this is a blocking request for an
<------><------><------> * already pending lock request then we need
<------><------><------> * to put it back on lockd's block list
<------><------><------> */
<------><------><------>if (wait)
<------><------><------><------>break;
<------><------><------>ret = nlm_lck_denied;
<------><------><------>goto out;
<------><------>case FILE_LOCK_DEFERRED:
<------><------><------>if (wait)
<------><------><------><------>break;
<------><------><------>/* Filesystem lock operation is in progress
<------><------><------>   Add it to the queue waiting for callback */
<------><------><------>ret = nlmsvc_defer_lock_rqst(rqstp, block);
<------><------><------>goto out;
<------><------>case -EDEADLK:
<------><------><------>ret = nlm_deadlock;
<------><------><------>goto out;
<------><------>default:			/* includes ENOLCK */
<------><------><------>ret = nlm_lck_denied_nolocks;
<------><------><------>goto out;
<------>}
 
<------>ret = nlm_lck_blocked;
 
<------>/* Append to list of blocked */
<------>nlmsvc_insert_block(block, NLM_NEVER);
out:
<------>mutex_unlock(&file->f_mutex);
<------>nlmsvc_release_block(block);
<------>dprintk("lockd: nlmsvc_lock returned %u\n", ret);
<------>return ret;
}
 
/*
 * Test for presence of a conflicting lock.
 */
__be32
nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
<------><------>struct nlm_host *host, struct nlm_lock *lock,
<------><------>struct nlm_lock *conflock, struct nlm_cookie *cookie)
{
<------>int			error;
<------>__be32			ret;
<------>struct nlm_lockowner	*test_owner;
 
<------>dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
<------><------><------><------>locks_inode(file->f_file)->i_sb->s_id,
<------><------><------><------>locks_inode(file->f_file)->i_ino,
<------><------><------><------>lock->fl.fl_type,
<------><------><------><------>(long long)lock->fl.fl_start,
<------><------><------><------>(long long)lock->fl.fl_end);
 
<------>if (locks_in_grace(SVC_NET(rqstp))) {
<------><------>ret = nlm_lck_denied_grace_period;
<------><------>goto out;
<------>}
 
<------>/* If there's a conflicting lock, remember to clean up the test lock */
<------>test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
 
<------>error = vfs_test_lock(file->f_file, &lock->fl);
<------>if (error) {
<------><------>/* We can't currently deal with deferred test requests */
<------><------>if (error == FILE_LOCK_DEFERRED)
<------><------><------>WARN_ON_ONCE(1);
 
<------><------>ret = nlm_lck_denied_nolocks;
<------><------>goto out;
<------>}
 
<------>if (lock->fl.fl_type == F_UNLCK) {
<------><------>ret = nlm_granted;
<------><------>goto out;
<------>}
 
<------>dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
<------><------>lock->fl.fl_type, (long long)lock->fl.fl_start,
<------><------>(long long)lock->fl.fl_end);
<------>conflock->caller = "somehost";	/* FIXME */
<------>conflock->len = strlen(conflock->caller);
<------>conflock->oh.len = 0;		/* don't return OH info */
<------>conflock->svid = lock->fl.fl_pid;
<------>conflock->fl.fl_type = lock->fl.fl_type;
<------>conflock->fl.fl_start = lock->fl.fl_start;
<------>conflock->fl.fl_end = lock->fl.fl_end;
<------>locks_release_private(&lock->fl);
 
<------>/* Clean up the test lock */
<------>lock->fl.fl_owner = NULL;
<------>nlmsvc_put_lockowner(test_owner);
 
<------>ret = nlm_lck_denied;
out:
<------>return ret;
}
 
/*
 * Remove a lock.
 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 * afterwards. In this case the block will still be there, and hence
 * must be removed.
 */
__be32
nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
{
<------>int	error;
 
<------>dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
<------><------><------><------>locks_inode(file->f_file)->i_sb->s_id,
<------><------><------><------>locks_inode(file->f_file)->i_ino,
<------><------><------><------>lock->fl.fl_pid,
<------><------><------><------>(long long)lock->fl.fl_start,
<------><------><------><------>(long long)lock->fl.fl_end);
 
<------>/* First, cancel any lock that might be there */
<------>nlmsvc_cancel_blocked(net, file, lock);
 
<------>lock->fl.fl_type = F_UNLCK;
<------>error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
 
<------>return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
}
 
/*
 * Cancel a previously blocked request.
 *
 * A cancel request always overrides any grant that may currently
 * be in progress.
 * The calling procedure must check whether the file can be closed.
 */
__be32
nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
{
<------>struct nlm_block	*block;
<------>int status = 0;
 
<------>dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
<------><------><------><------>locks_inode(file->f_file)->i_sb->s_id,
<------><------><------><------>locks_inode(file->f_file)->i_ino,
<------><------><------><------>lock->fl.fl_pid,
<------><------><------><------>(long long)lock->fl.fl_start,
<------><------><------><------>(long long)lock->fl.fl_end);
 
<------>if (locks_in_grace(net))
<------><------>return nlm_lck_denied_grace_period;
 
<------>mutex_lock(&file->f_mutex);
<------>block = nlmsvc_lookup_block(file, lock);
<------>mutex_unlock(&file->f_mutex);
<------>if (block != NULL) {
<------><------>vfs_cancel_lock(block->b_file->f_file,
<------><------><------><------>&block->b_call->a_args.lock.fl);
<------><------>status = nlmsvc_unlink_block(block);
<------><------>nlmsvc_release_block(block);
<------>}
<------>return status ? nlm_lck_denied : nlm_granted;
}
 
/*
 * This is a callback from the filesystem for VFS file lock requests.
 * It will be used if lm_grant is defined and the filesystem can not
 * respond to the request immediately.
 * For SETLK or SETLKW request it will get the local posix lock.
 * In all cases it will move the block to the head of nlm_blocked q where
 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
 * deferred rpc for GETLK and SETLK.
 */
static void
nlmsvc_update_deferred_block(struct nlm_block *block, int result)
{
<------>block->b_flags |= B_GOT_CALLBACK;
<------>if (result == 0)
<------><------>block->b_granted = 1;
<------>else
<------><------>block->b_flags |= B_TIMED_OUT;
}
 
static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
{
<------>struct nlm_block *block;
<------>int rc = -ENOENT;
 
<------>spin_lock(&nlm_blocked_lock);
<------>list_for_each_entry(block, &nlm_blocked, b_list) {
<------><------>if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
<------><------><------>dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
<------><------><------><------><------><------><------>block, block->b_flags);
<------><------><------>if (block->b_flags & B_QUEUED) {
<------><------><------><------>if (block->b_flags & B_TIMED_OUT) {
<------><------><------><------><------>rc = -ENOLCK;
<------><------><------><------><------>break;
<------><------><------><------>}
<------><------><------><------>nlmsvc_update_deferred_block(block, result);
<------><------><------>} else if (result == 0)
<------><------><------><------>block->b_granted = 1;
 
<------><------><------>nlmsvc_insert_block_locked(block, 0);
<------><------><------>svc_wake_up(block->b_daemon);
<------><------><------>rc = 0;
<------><------><------>break;
<------><------>}
<------>}
<------>spin_unlock(&nlm_blocked_lock);
<------>if (rc == -ENOENT)
<------><------>printk(KERN_WARNING "lockd: grant for unknown block\n");
<------>return rc;
}
 
/*
 * Unblock a blocked lock request. This is a callback invoked from the
 * VFS layer when a lock on which we blocked is removed.
 *
 * This function doesn't grant the blocked lock instantly, but rather moves
 * the block to the head of nlm_blocked where it can be picked up by lockd.
 */
static void
nlmsvc_notify_blocked(struct file_lock *fl)
{
<------>struct nlm_block	*block;
 
<------>dprintk("lockd: VFS unblock notification for block %p\n", fl);
<------>spin_lock(&nlm_blocked_lock);
<------>list_for_each_entry(block, &nlm_blocked, b_list) {
<------><------>if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
<------><------><------>nlmsvc_insert_block_locked(block, 0);
<------><------><------>spin_unlock(&nlm_blocked_lock);
<------><------><------>svc_wake_up(block->b_daemon);
<------><------><------>return;
<------><------>}
<------>}
<------>spin_unlock(&nlm_blocked_lock);
<------>printk(KERN_WARNING "lockd: notification for unknown block!\n");
}
 
static fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
{
<------>return nlmsvc_get_lockowner(owner);
}
 
static void nlmsvc_put_owner(fl_owner_t owner)
{
<------>nlmsvc_put_lockowner(owner);
}
 
const struct lock_manager_operations nlmsvc_lock_operations = {
<------>.lm_notify = nlmsvc_notify_blocked,
<------>.lm_grant = nlmsvc_grant_deferred,
<------>.lm_get_owner = nlmsvc_get_owner,
<------>.lm_put_owner = nlmsvc_put_owner,
};
 
/*
 * Try to claim a lock that was previously blocked.
 *
 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 * RPC thread when notifying the client. This seems like overkill...
 * Here's why:
 *  -	we don't want to use a synchronous RPC thread, otherwise
 *	we might find ourselves hanging on a dead portmapper.
 *  -	Some lockd implementations (e.g. HP) don't react to
 *	RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 */
static void
nlmsvc_grant_blocked(struct nlm_block *block)
{
<------>struct nlm_file		*file = block->b_file;
<------>struct nlm_lock		*lock = &block->b_call->a_args.lock;
<------>int			error;
<------>loff_t			fl_start, fl_end;
 
<------>dprintk("lockd: grant blocked lock %p\n", block);
 
<------>kref_get(&block->b_count);
 
<------>/* Unlink block request from list */
<------>nlmsvc_unlink_block(block);
 
<------>/* If b_granted is true this means we've been here before.
<------> * Just retry the grant callback, possibly refreshing the RPC
<------> * binding */
<------>if (block->b_granted) {
<------><------>nlm_rebind_host(block->b_host);
<------><------>goto callback;
<------>}
 
<------>/* Try the lock operation again */
<------>/* vfs_lock_file() can mangle fl_start and fl_end, but we need
<------> * them unchanged for the GRANT_MSG
<------> */
<------>lock->fl.fl_flags |= FL_SLEEP;
<------>fl_start = lock->fl.fl_start;
<------>fl_end = lock->fl.fl_end;
<------>error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
<------>lock->fl.fl_flags &= ~FL_SLEEP;
<------>lock->fl.fl_start = fl_start;
<------>lock->fl.fl_end = fl_end;
 
<------>switch (error) {
<------>case 0:
<------><------>break;
<------>case FILE_LOCK_DEFERRED:
<------><------>dprintk("lockd: lock still blocked error %d\n", error);
<------><------>nlmsvc_insert_block(block, NLM_NEVER);
<------><------>nlmsvc_release_block(block);
<------><------>return;
<------>default:
<------><------>printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
<------><------><------><------>-error, __func__);
<------><------>nlmsvc_insert_block(block, 10 * HZ);
<------><------>nlmsvc_release_block(block);
<------><------>return;
<------>}
 
callback:
<------>/* Lock was granted by VFS. */
<------>dprintk("lockd: GRANTing blocked lock.\n");
<------>block->b_granted = 1;
 
<------>/* keep block on the list, but don't reattempt until the RPC
<------> * completes or the submission fails
<------> */
<------>nlmsvc_insert_block(block, NLM_NEVER);
 
<------>/* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
<------> * will queue up a new one if this one times out
<------> */
<------>error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
<------><------><------><------>&nlmsvc_grant_ops);
 
<------>/* RPC submission failed, wait a bit and retry */
<------>if (error < 0)
<------><------>nlmsvc_insert_block(block, 10 * HZ);
}
 
/*
 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 * RPC call has succeeded or timed out.
 * Like all RPC callbacks, it is invoked by the rpciod process, so it
 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 * chain once more in order to have it removed by lockd itself (which can
 * then sleep on the file semaphore without disrupting e.g. the nfs client).
 */
static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
{
<------>struct nlm_rqst		*call = data;
<------>struct nlm_block	*block = call->a_block;
<------>unsigned long		timeout;
 
<------>dprintk("lockd: GRANT_MSG RPC callback\n");
 
<------>spin_lock(&nlm_blocked_lock);
<------>/* if the block is not on a list at this point then it has
<------> * been invalidated. Don't try to requeue it.
<------> *
<------> * FIXME: it's possible that the block is removed from the list
<------> * after this check but before the nlmsvc_insert_block. In that
<------> * case it will be added back. Perhaps we need better locking
<------> * for nlm_blocked?
<------> */
<------>if (list_empty(&block->b_list))
<------><------>goto out;
 
<------>/* Technically, we should down the file semaphore here. Since we
<------> * move the block towards the head of the queue only, no harm
<------> * can be done, though. */
<------>if (task->tk_status < 0) {
<------><------>/* RPC error: Re-insert for retransmission */
<------><------>timeout = 10 * HZ;
<------>} else {
<------><------>/* Call was successful, now wait for client callback */
<------><------>timeout = 60 * HZ;
<------>}
<------>nlmsvc_insert_block_locked(block, timeout);
<------>svc_wake_up(block->b_daemon);
out:
<------>spin_unlock(&nlm_blocked_lock);
}
 
/*
 * FIXME: nlmsvc_release_block() grabs a mutex.  This is not allowed for an
 * .rpc_release rpc_call_op
 */
static void nlmsvc_grant_release(void *data)
{
<------>struct nlm_rqst		*call = data;
<------>nlmsvc_release_block(call->a_block);
}
 
static const struct rpc_call_ops nlmsvc_grant_ops = {
<------>.rpc_call_done = nlmsvc_grant_callback,
<------>.rpc_release = nlmsvc_grant_release,
};
 
/*
 * We received a GRANT_RES callback. Try to find the corresponding
 * block.
 */
void
nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
{
<------>struct nlm_block	*block;
 
<------>dprintk("grant_reply: looking for cookie %x, s=%d \n",
<------><------>*(unsigned int *)(cookie->data), status);
<------>if (!(block = nlmsvc_find_block(cookie)))
<------><------>return;
 
<------>if (status == nlm_lck_denied_grace_period) {
<------><------>/* Try again in a couple of seconds */
<------><------>nlmsvc_insert_block(block, 10 * HZ);
<------>} else {
<------><------>/*
<------><------> * Lock is now held by client, or has been rejected.
<------><------> * In both cases, the block should be removed.
<------><------> */
<------><------>nlmsvc_unlink_block(block);
<------>}
<------>nlmsvc_release_block(block);
}
 
/* Helper function to handle retry of a deferred block.
 * If it is a blocking lock, call grant_blocked.
 * For a non-blocking lock or test lock, revisit the request.
 */
static void
retry_deferred_block(struct nlm_block *block)
{
<------>if (!(block->b_flags & B_GOT_CALLBACK))
<------><------>block->b_flags |= B_TIMED_OUT;
<------>nlmsvc_insert_block(block, NLM_TIMEOUT);
<------>dprintk("revisit block %p flags %d\n",	block, block->b_flags);
<------>if (block->b_deferred_req) {
<------><------>block->b_deferred_req->revisit(block->b_deferred_req, 0);
<------><------>block->b_deferred_req = NULL;
<------>}
}
 
/*
 * Retry all blocked locks that have been notified. This is where lockd
 * picks up locks that can be granted, or grant notifications that must
 * be retransmitted.
 */
unsigned long
nlmsvc_retry_blocked(void)
{
<------>unsigned long	timeout = MAX_SCHEDULE_TIMEOUT;
<------>struct nlm_block *block;
 
<------>spin_lock(&nlm_blocked_lock);
<------>while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
<------><------>block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
 
<------><------>if (block->b_when == NLM_NEVER)
<------><------><------>break;
<------><------>if (time_after(block->b_when, jiffies)) {
<------><------><------>timeout = block->b_when - jiffies;
<------><------><------>break;
<------><------>}
<------><------>spin_unlock(&nlm_blocked_lock);
 
<------><------>dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
<------><------><------>block, block->b_when);
<------><------>if (block->b_flags & B_QUEUED) {
<------><------><------>dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
<------><------><------><------>block, block->b_granted, block->b_flags);
<------><------><------>retry_deferred_block(block);
<------><------>} else
<------><------><------>nlmsvc_grant_blocked(block);
<------><------>spin_lock(&nlm_blocked_lock);
<------>}
<------>spin_unlock(&nlm_blocked_lock);
 
<------>return timeout;
}