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![J. Bruce Fields](/assets/img/avatar_default.png)
NFSv4.1 supports an optional lock notification feature which notifies the client when a lock comes available. (Normally NFSv4 clients just poll for locks if necessary.) To make that work, we need to request a blocking lock from the filesystem. We turned that off for NFS in commitf657f8eef3
("nfs: don't atempt blocking locks on nfs reexports") [sic] because it actually blocks the nfsd thread while waiting for the lock. Thanks to Vasily Averin for pointing out that NFS isn't the only filesystem with that problem. Any filesystem that leaves ->lock NULL will use posix_lock_file(), which does the right thing. Simplest is just to assume that any filesystem that defines its own ->lock is not safe to request a blocking lock from. So, this patch mostly reverts commitf657f8eef3
("nfs: don't atempt blocking locks on nfs reexports") [sic] and commitb840be2f00
("lockd: don't attempt blocking locks on nfs reexports"), and instead uses a check of ->lock (Vasily's suggestion) to decide whether to support blocking lock notifications on a given filesystem. Also add a little documentation. Perhaps someday we could add back an export flag later to allow filesystems with "good" ->lock methods to support blocking lock notifications. Reported-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> [ cel: Description rewritten to address checkpatch nits ] [ cel: Fixed warning when SUNRPC debugging is disabled ] [ cel: Fixed NULL check ] Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Vasily Averin <vvs@virtuozzo.com>
1034 lines
27 KiB
C
1034 lines
27 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/lockd/svclock.c
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*
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* Handling of server-side locks, mostly of the blocked variety.
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* This is the ugliest part of lockd because we tread on very thin ice.
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* GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
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* IMNSHO introducing the grant callback into the NLM protocol was one
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* of the worst ideas Sun ever had. Except maybe for the idea of doing
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* NFS file locking at all.
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*
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* I'm trying hard to avoid race conditions by protecting most accesses
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* to a file's list of blocked locks through a semaphore. The global
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* list of blocked locks is not protected in this fashion however.
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* Therefore, some functions (such as the RPC callback for the async grant
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* call) move blocked locks towards the head of the list *while some other
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* process might be traversing it*. This should not be a problem in
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* practice, because this will only cause functions traversing the list
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* to visit some blocks twice.
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*
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* Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
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*/
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/sunrpc/svc_xprt.h>
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#include <linux/lockd/nlm.h>
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#include <linux/lockd/lockd.h>
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#include <linux/kthread.h>
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#include <linux/exportfs.h>
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#define NLMDBG_FACILITY NLMDBG_SVCLOCK
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#ifdef CONFIG_LOCKD_V4
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#define nlm_deadlock nlm4_deadlock
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#else
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#define nlm_deadlock nlm_lck_denied
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#endif
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static void nlmsvc_release_block(struct nlm_block *block);
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static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
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static void nlmsvc_remove_block(struct nlm_block *block);
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static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
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static void nlmsvc_freegrantargs(struct nlm_rqst *call);
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static const struct rpc_call_ops nlmsvc_grant_ops;
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/*
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* The list of blocked locks to retry
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*/
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static LIST_HEAD(nlm_blocked);
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static DEFINE_SPINLOCK(nlm_blocked_lock);
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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
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static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
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{
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/*
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* We can get away with a static buffer because this is only called
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* from lockd, which is single-threaded.
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*/
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static char buf[2*NLM_MAXCOOKIELEN+1];
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unsigned int i, len = sizeof(buf);
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char *p = buf;
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len--; /* allow for trailing \0 */
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if (len < 3)
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return "???";
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for (i = 0 ; i < cookie->len ; i++) {
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if (len < 2) {
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strcpy(p-3, "...");
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break;
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}
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sprintf(p, "%02x", cookie->data[i]);
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p += 2;
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len -= 2;
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}
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*p = '\0';
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return buf;
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}
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#endif
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/*
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* Insert a blocked lock into the global list
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*/
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static void
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nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
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{
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struct nlm_block *b;
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struct list_head *pos;
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dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
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if (list_empty(&block->b_list)) {
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kref_get(&block->b_count);
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} else {
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list_del_init(&block->b_list);
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}
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pos = &nlm_blocked;
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if (when != NLM_NEVER) {
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if ((when += jiffies) == NLM_NEVER)
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when ++;
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list_for_each(pos, &nlm_blocked) {
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b = list_entry(pos, struct nlm_block, b_list);
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if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
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break;
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}
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/* On normal exit from the loop, pos == &nlm_blocked,
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* so we will be adding to the end of the list - good
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*/
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}
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list_add_tail(&block->b_list, pos);
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block->b_when = when;
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}
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static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
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{
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spin_lock(&nlm_blocked_lock);
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nlmsvc_insert_block_locked(block, when);
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spin_unlock(&nlm_blocked_lock);
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}
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/*
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* Remove a block from the global list
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*/
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static inline void
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nlmsvc_remove_block(struct nlm_block *block)
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{
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if (!list_empty(&block->b_list)) {
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spin_lock(&nlm_blocked_lock);
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list_del_init(&block->b_list);
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spin_unlock(&nlm_blocked_lock);
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nlmsvc_release_block(block);
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}
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}
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/*
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* Find a block for a given lock
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*/
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static struct nlm_block *
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nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
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{
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struct nlm_block *block;
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struct file_lock *fl;
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dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
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file, lock->fl.fl_pid,
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(long long)lock->fl.fl_start,
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(long long)lock->fl.fl_end, lock->fl.fl_type);
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list_for_each_entry(block, &nlm_blocked, b_list) {
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fl = &block->b_call->a_args.lock.fl;
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dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
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block->b_file, fl->fl_pid,
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(long long)fl->fl_start,
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(long long)fl->fl_end, fl->fl_type,
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nlmdbg_cookie2a(&block->b_call->a_args.cookie));
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if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
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kref_get(&block->b_count);
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return block;
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}
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}
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return NULL;
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}
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static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
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{
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if (a->len != b->len)
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return 0;
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if (memcmp(a->data, b->data, a->len))
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return 0;
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return 1;
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}
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/*
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* Find a block with a given NLM cookie.
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*/
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static inline struct nlm_block *
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nlmsvc_find_block(struct nlm_cookie *cookie)
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{
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struct nlm_block *block;
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list_for_each_entry(block, &nlm_blocked, b_list) {
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if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
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goto found;
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}
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return NULL;
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found:
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dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
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kref_get(&block->b_count);
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return block;
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}
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/*
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* Create a block and initialize it.
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*
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* Note: we explicitly set the cookie of the grant reply to that of
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* the blocked lock request. The spec explicitly mentions that the client
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* should _not_ rely on the callback containing the same cookie as the
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* request, but (as I found out later) that's because some implementations
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* do just this. Never mind the standards comittees, they support our
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* logging industries.
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*
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* 10 years later: I hope we can safely ignore these old and broken
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* clients by now. Let's fix this so we can uniquely identify an incoming
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* GRANTED_RES message by cookie, without having to rely on the client's IP
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* address. --okir
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*/
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static struct nlm_block *
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nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
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struct nlm_file *file, struct nlm_lock *lock,
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struct nlm_cookie *cookie)
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{
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struct nlm_block *block;
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struct nlm_rqst *call = NULL;
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call = nlm_alloc_call(host);
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if (call == NULL)
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return NULL;
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/* Allocate memory for block, and initialize arguments */
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block = kzalloc(sizeof(*block), GFP_KERNEL);
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if (block == NULL)
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goto failed;
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kref_init(&block->b_count);
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INIT_LIST_HEAD(&block->b_list);
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INIT_LIST_HEAD(&block->b_flist);
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if (!nlmsvc_setgrantargs(call, lock))
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goto failed_free;
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/* Set notifier function for VFS, and init args */
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call->a_args.lock.fl.fl_flags |= FL_SLEEP;
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call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
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nlmclnt_next_cookie(&call->a_args.cookie);
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dprintk("lockd: created block %p...\n", block);
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/* Create and initialize the block */
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block->b_daemon = rqstp->rq_server;
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block->b_host = host;
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block->b_file = file;
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file->f_count++;
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/* Add to file's list of blocks */
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list_add(&block->b_flist, &file->f_blocks);
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/* Set up RPC arguments for callback */
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block->b_call = call;
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call->a_flags = RPC_TASK_ASYNC;
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call->a_block = block;
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return block;
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failed_free:
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kfree(block);
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failed:
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nlmsvc_release_call(call);
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return NULL;
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}
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/*
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* Delete a block.
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* It is the caller's responsibility to check whether the file
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* can be closed hereafter.
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*/
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static int nlmsvc_unlink_block(struct nlm_block *block)
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{
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int status;
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dprintk("lockd: unlinking block %p...\n", block);
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/* Remove block from list */
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status = locks_delete_block(&block->b_call->a_args.lock.fl);
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nlmsvc_remove_block(block);
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return status;
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}
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static void nlmsvc_free_block(struct kref *kref)
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{
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struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
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struct nlm_file *file = block->b_file;
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dprintk("lockd: freeing block %p...\n", block);
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/* Remove block from file's list of blocks */
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list_del_init(&block->b_flist);
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mutex_unlock(&file->f_mutex);
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nlmsvc_freegrantargs(block->b_call);
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nlmsvc_release_call(block->b_call);
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nlm_release_file(block->b_file);
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kfree(block);
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}
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static void nlmsvc_release_block(struct nlm_block *block)
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{
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if (block != NULL)
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kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
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}
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/*
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* Loop over all blocks and delete blocks held by
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* a matching host.
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*/
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void nlmsvc_traverse_blocks(struct nlm_host *host,
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struct nlm_file *file,
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nlm_host_match_fn_t match)
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{
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struct nlm_block *block, *next;
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restart:
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mutex_lock(&file->f_mutex);
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list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
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if (!match(block->b_host, host))
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continue;
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/* Do not destroy blocks that are not on
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* the global retry list - why? */
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if (list_empty(&block->b_list))
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continue;
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kref_get(&block->b_count);
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mutex_unlock(&file->f_mutex);
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nlmsvc_unlink_block(block);
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nlmsvc_release_block(block);
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goto restart;
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}
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mutex_unlock(&file->f_mutex);
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}
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static struct nlm_lockowner *
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nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
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{
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refcount_inc(&lockowner->count);
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return lockowner;
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}
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static void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
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{
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if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
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return;
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list_del(&lockowner->list);
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spin_unlock(&lockowner->host->h_lock);
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nlmsvc_release_host(lockowner->host);
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kfree(lockowner);
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}
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static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
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{
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struct nlm_lockowner *lockowner;
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list_for_each_entry(lockowner, &host->h_lockowners, list) {
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if (lockowner->pid != pid)
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continue;
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return nlmsvc_get_lockowner(lockowner);
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}
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return NULL;
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}
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static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
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{
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struct nlm_lockowner *res, *new = NULL;
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spin_lock(&host->h_lock);
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res = __nlmsvc_find_lockowner(host, pid);
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if (res == NULL) {
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spin_unlock(&host->h_lock);
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new = kmalloc(sizeof(*res), GFP_KERNEL);
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spin_lock(&host->h_lock);
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res = __nlmsvc_find_lockowner(host, pid);
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if (res == NULL && new != NULL) {
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res = new;
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/* fs/locks.c will manage the refcount through lock_ops */
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refcount_set(&new->count, 1);
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new->pid = pid;
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new->host = nlm_get_host(host);
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list_add(&new->list, &host->h_lockowners);
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new = NULL;
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}
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}
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spin_unlock(&host->h_lock);
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kfree(new);
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return res;
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}
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void
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nlmsvc_release_lockowner(struct nlm_lock *lock)
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{
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if (lock->fl.fl_owner)
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nlmsvc_put_lockowner(lock->fl.fl_owner);
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}
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|
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void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
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pid_t pid)
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{
|
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fl->fl_owner = nlmsvc_find_lockowner(host, pid);
|
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}
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|
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/*
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* Initialize arguments for GRANTED call. The nlm_rqst structure
|
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* has been cleared already.
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*/
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static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
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{
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locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
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memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
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call->a_args.lock.caller = utsname()->nodename;
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call->a_args.lock.oh.len = lock->oh.len;
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|
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/* set default data area */
|
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call->a_args.lock.oh.data = call->a_owner;
|
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call->a_args.lock.svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
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|
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if (lock->oh.len > NLMCLNT_OHSIZE) {
|
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void *data = kmalloc(lock->oh.len, GFP_KERNEL);
|
|
if (!data)
|
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return 0;
|
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call->a_args.lock.oh.data = (u8 *) data;
|
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}
|
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|
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memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
|
|
return 1;
|
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}
|
|
|
|
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)
|
|
{
|
|
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
|
|
struct inode *inode = nlmsvc_file_inode(file);
|
|
#endif
|
|
struct nlm_block *block = NULL;
|
|
int error;
|
|
int mode;
|
|
int async_block = 0;
|
|
__be32 ret;
|
|
|
|
dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
|
|
inode->i_sb->s_id, inode->i_ino,
|
|
lock->fl.fl_type, lock->fl.fl_pid,
|
|
(long long)lock->fl.fl_start,
|
|
(long long)lock->fl.fl_end,
|
|
wait);
|
|
|
|
if (nlmsvc_file_file(file)->f_op->lock) {
|
|
async_block = wait;
|
|
wait = 0;
|
|
}
|
|
|
|
/* 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;
|
|
mode = lock_to_openmode(&lock->fl);
|
|
error = vfs_lock_file(file->f_file[mode], 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 = async_block ? nlm_lck_blocked : 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;
|
|
int mode;
|
|
__be32 ret;
|
|
struct nlm_lockowner *test_owner;
|
|
|
|
dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
|
|
nlmsvc_file_inode(file)->i_sb->s_id,
|
|
nlmsvc_file_inode(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;
|
|
|
|
mode = lock_to_openmode(&lock->fl);
|
|
error = vfs_test_lock(file->f_file[mode], &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 = 0;
|
|
|
|
dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
|
|
nlmsvc_file_inode(file)->i_sb->s_id,
|
|
nlmsvc_file_inode(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;
|
|
if (file->f_file[O_RDONLY])
|
|
error = vfs_lock_file(file->f_file[O_RDONLY], F_SETLK,
|
|
&lock->fl, NULL);
|
|
if (file->f_file[O_WRONLY])
|
|
error = vfs_lock_file(file->f_file[O_WRONLY], 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;
|
|
int mode;
|
|
|
|
dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
|
|
nlmsvc_file_inode(file)->i_sb->s_id,
|
|
nlmsvc_file_inode(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) {
|
|
mode = lock_to_openmode(&lock->fl);
|
|
vfs_cancel_lock(block->b_file->f_file[mode],
|
|
&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 mode;
|
|
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;
|
|
mode = lock_to_openmode(&lock->fl);
|
|
error = vfs_lock_file(file->f_file[mode], 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;
|
|
}
|