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![Amir Goldstein](/assets/img/avatar_default.png)
nfsd and lockd call vfs_lock_file() to lock/unlock the inode
returned by locks_inode(file).
Many places in nfsd/lockd code use the inode returned by
file_inode(file) for lock manipulation. With Overlayfs, file_inode()
(the underlying inode) is not the same object as locks_inode() (the
overlay inode). This can result in "Leaked POSIX lock" messages
and eventually to a kernel crash as reported by Eddie Horng:
https://marc.info/?l=linux-unionfs&m=153086643202072&w=2
Fix all the call sites in nfsd/lockd that should use locks_inode().
This is a correctness bug that manifested when overlayfs gained
NFS export support in v4.16.
Reported-by: Eddie Horng <eddiehorng.tw@gmail.com>
Tested-by: Eddie Horng <eddiehorng.tw@gmail.com>
Cc: Jeff Layton <jlayton@kernel.org>
Fixes: 8383f17488
("ovl: wire up NFS export operations")
Cc: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
940 lines
25 KiB
C
940 lines
25 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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#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 = posix_unblock_lock(&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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/*
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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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/* 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 = lock->fl.fl_pid;
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if (lock->oh.len > NLMCLNT_OHSIZE) {
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void *data = kmalloc(lock->oh.len, GFP_KERNEL);
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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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memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
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return 1;
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}
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static void nlmsvc_freegrantargs(struct nlm_rqst *call)
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{
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if (call->a_args.lock.oh.data != call->a_owner)
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kfree(call->a_args.lock.oh.data);
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locks_release_private(&call->a_args.lock.fl);
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}
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/*
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* Deferred lock request handling for non-blocking lock
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*/
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static __be32
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nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
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{
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__be32 status = nlm_lck_denied_nolocks;
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block->b_flags |= B_QUEUED;
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nlmsvc_insert_block(block, NLM_TIMEOUT);
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block->b_cache_req = &rqstp->rq_chandle;
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if (rqstp->rq_chandle.defer) {
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block->b_deferred_req =
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rqstp->rq_chandle.defer(block->b_cache_req);
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if (block->b_deferred_req != NULL)
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status = nlm_drop_reply;
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}
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dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
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block, block->b_flags, ntohl(status));
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return status;
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}
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/*
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* Attempt to establish a lock, and if it can't be granted, block it
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* if required.
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*/
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__be32
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nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
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struct nlm_host *host, struct nlm_lock *lock, int wait,
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struct nlm_cookie *cookie, int reclaim)
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{
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struct nlm_block *block = NULL;
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int error;
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__be32 ret;
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dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
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locks_inode(file->f_file)->i_sb->s_id,
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locks_inode(file->f_file)->i_ino,
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lock->fl.fl_type, lock->fl.fl_pid,
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(long long)lock->fl.fl_start,
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(long long)lock->fl.fl_end,
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wait);
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/* Lock file against concurrent access */
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mutex_lock(&file->f_mutex);
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/* Get existing block (in case client is busy-waiting)
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* or create new block
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*/
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block = nlmsvc_lookup_block(file, lock);
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if (block == NULL) {
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block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
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ret = nlm_lck_denied_nolocks;
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if (block == NULL)
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goto out;
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lock = &block->b_call->a_args.lock;
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} else
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lock->fl.fl_flags &= ~FL_SLEEP;
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if (block->b_flags & B_QUEUED) {
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dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
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block, block->b_flags);
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if (block->b_granted) {
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nlmsvc_unlink_block(block);
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ret = nlm_granted;
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goto out;
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}
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if (block->b_flags & B_TIMED_OUT) {
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nlmsvc_unlink_block(block);
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ret = nlm_lck_denied;
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goto out;
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}
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ret = nlm_drop_reply;
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goto out;
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}
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if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
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ret = nlm_lck_denied_grace_period;
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goto out;
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}
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if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
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ret = nlm_lck_denied_grace_period;
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goto out;
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}
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if (!wait)
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lock->fl.fl_flags &= ~FL_SLEEP;
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error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
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lock->fl.fl_flags &= ~FL_SLEEP;
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dprintk("lockd: vfs_lock_file returned %d\n", error);
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switch (error) {
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case 0:
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ret = nlm_granted;
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goto out;
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case -EAGAIN:
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/*
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* If this is a blocking request for an
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* already pending lock request then we need
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* to put it back on lockd's block list
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*/
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if (wait)
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break;
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|
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;
|
|
|
|
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;
|
|
}
|
|
|
|
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);
|
|
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 int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
|
|
{
|
|
return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
|
|
}
|
|
|
|
/*
|
|
* Since NLM uses two "keys" for tracking locks, we need to hash them down
|
|
* to one for the blocked_hash. Here, we're just xor'ing the host address
|
|
* with the pid in order to create a key value for picking a hash bucket.
|
|
*/
|
|
static unsigned long
|
|
nlmsvc_owner_key(struct file_lock *fl)
|
|
{
|
|
return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
|
|
}
|
|
|
|
const struct lock_manager_operations nlmsvc_lock_operations = {
|
|
.lm_compare_owner = nlmsvc_same_owner,
|
|
.lm_owner_key = nlmsvc_owner_key,
|
|
.lm_notify = nlmsvc_notify_blocked,
|
|
.lm_grant = nlmsvc_grant_deferred,
|
|
};
|
|
|
|
/*
|
|
* 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;
|
|
}
|