1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
686 lines
18 KiB
C
686 lines
18 KiB
C
/*
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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/config.h>
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#include <linux/types.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/smp_lock.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/sunrpc/svc.h>
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#include <linux/lockd/nlm.h>
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#include <linux/lockd/lockd.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_insert_block(struct nlm_block *block, unsigned long);
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static int nlmsvc_remove_block(struct nlm_block *block);
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static void nlmsvc_grant_callback(struct rpc_task *task);
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/*
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* The list of blocked locks to retry
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*/
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static struct nlm_block * nlm_blocked;
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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(struct nlm_block *block, unsigned long when)
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{
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struct nlm_block **bp, *b;
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dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
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if (block->b_queued)
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nlmsvc_remove_block(block);
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bp = &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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while ((b = *bp) && time_before_eq(b->b_when,when) && b->b_when != NLM_NEVER)
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bp = &b->b_next;
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} else
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while ((b = *bp) != 0)
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bp = &b->b_next;
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block->b_queued = 1;
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block->b_when = when;
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block->b_next = b;
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*bp = block;
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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 int
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nlmsvc_remove_block(struct nlm_block *block)
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{
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struct nlm_block **bp, *b;
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if (!block->b_queued)
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return 1;
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for (bp = &nlm_blocked; (b = *bp) != 0; bp = &b->b_next) {
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if (b == block) {
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*bp = block->b_next;
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block->b_queued = 0;
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return 1;
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}
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}
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return 0;
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}
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/*
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* Find a block for a given lock and optionally remove it from
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* the list.
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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, int remove)
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{
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struct nlm_block **head, *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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for (head = &nlm_blocked; (block = *head) != 0; head = &block->b_next) {
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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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if (remove) {
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*head = block->b_next;
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block->b_queued = 0;
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}
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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, struct sockaddr_in *sin)
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{
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struct nlm_block *block;
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for (block = nlm_blocked; block; block = block->b_next) {
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dprintk("cookie: head of blocked queue %p, block %p\n",
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nlm_blocked, block);
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if (nlm_cookie_match(&block->b_call.a_args.cookie,cookie)
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&& nlm_cmp_addr(sin, &block->b_host->h_addr))
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break;
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}
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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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static inline struct nlm_block *
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nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
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struct nlm_lock *lock, struct nlm_cookie *cookie)
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{
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struct nlm_block *block;
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struct nlm_host *host;
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struct nlm_rqst *call;
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/* Create host handle for callback */
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host = nlmclnt_lookup_host(&rqstp->rq_addr,
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rqstp->rq_prot, rqstp->rq_vers);
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if (host == NULL)
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return NULL;
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/* Allocate memory for block, and initialize arguments */
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if (!(block = (struct nlm_block *) kmalloc(sizeof(*block), GFP_KERNEL)))
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goto failed;
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memset(block, 0, sizeof(*block));
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locks_init_lock(&block->b_call.a_args.lock.fl);
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locks_init_lock(&block->b_call.a_res.lock.fl);
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if (!nlmclnt_setgrantargs(&block->b_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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block->b_call.a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
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block->b_call.a_args.cookie = *cookie; /* see above */
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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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/* Add to file's list of blocks */
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block->b_fnext = file->f_blocks;
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file->f_blocks = block;
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/* Set up RPC arguments for callback */
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call = &block->b_call;
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call->a_host = host;
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call->a_flags = RPC_TASK_ASYNC;
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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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nlm_release_host(host);
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return NULL;
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}
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/*
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* Delete a block. If the lock was cancelled or the grant callback
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* failed, unlock is set to 1.
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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 void
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nlmsvc_delete_block(struct nlm_block *block, int unlock)
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{
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struct file_lock *fl = &block->b_call.a_args.lock.fl;
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struct nlm_file *file = block->b_file;
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struct nlm_block **bp;
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dprintk("lockd: deleting block %p...\n", block);
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/* Remove block from list */
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nlmsvc_remove_block(block);
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if (fl->fl_next)
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posix_unblock_lock(file->f_file, fl);
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if (unlock) {
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fl->fl_type = F_UNLCK;
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posix_lock_file(file->f_file, fl);
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block->b_granted = 0;
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}
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/* If the block is in the middle of a GRANT callback,
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* don't kill it yet. */
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if (block->b_incall) {
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nlmsvc_insert_block(block, NLM_NEVER);
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block->b_done = 1;
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return;
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}
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/* Remove block from file's list of blocks */
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for (bp = &file->f_blocks; *bp; bp = &(*bp)->b_fnext) {
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if (*bp == block) {
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*bp = block->b_fnext;
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break;
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}
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}
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if (block->b_host)
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nlm_release_host(block->b_host);
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nlmclnt_freegrantargs(&block->b_call);
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kfree(block);
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}
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/*
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* Loop over all blocks and perform the action specified.
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* (NLM_ACT_CHECK handled by nlmsvc_inspect_file).
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*/
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int
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nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action)
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{
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struct nlm_block *block, *next;
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down(&file->f_sema);
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for (block = file->f_blocks; block; block = next) {
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next = block->b_fnext;
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if (action == NLM_ACT_MARK)
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block->b_host->h_inuse = 1;
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else if (action == NLM_ACT_UNLOCK) {
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if (host == NULL || host == block->b_host)
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nlmsvc_delete_block(block, 1);
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}
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}
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up(&file->f_sema);
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return 0;
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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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u32
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nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
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struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
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{
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struct file_lock *conflock;
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struct nlm_block *block;
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int error;
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dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
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file->f_file->f_dentry->d_inode->i_sb->s_id,
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file->f_file->f_dentry->d_inode->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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/* Get existing block (in case client is busy-waiting) */
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block = nlmsvc_lookup_block(file, lock, 0);
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lock->fl.fl_flags |= FL_LOCKD;
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again:
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/* Lock file against concurrent access */
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down(&file->f_sema);
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if (!(conflock = posix_test_lock(file->f_file, &lock->fl))) {
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error = posix_lock_file(file->f_file, &lock->fl);
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if (block)
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nlmsvc_delete_block(block, 0);
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up(&file->f_sema);
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dprintk("lockd: posix_lock_file returned %d\n", -error);
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switch(-error) {
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case 0:
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return nlm_granted;
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case EDEADLK:
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return nlm_deadlock;
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case EAGAIN:
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return nlm_lck_denied;
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default: /* includes ENOLCK */
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return nlm_lck_denied_nolocks;
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}
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}
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if (!wait) {
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up(&file->f_sema);
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return nlm_lck_denied;
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}
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if (posix_locks_deadlock(&lock->fl, conflock)) {
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up(&file->f_sema);
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return nlm_deadlock;
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}
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/* If we don't have a block, create and initialize it. Then
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* retry because we may have slept in kmalloc. */
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/* We have to release f_sema as nlmsvc_create_block may try to
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* to claim it while doing host garbage collection */
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if (block == NULL) {
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up(&file->f_sema);
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dprintk("lockd: blocking on this lock (allocating).\n");
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if (!(block = nlmsvc_create_block(rqstp, file, lock, cookie)))
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return nlm_lck_denied_nolocks;
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goto again;
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}
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/* Append to list of blocked */
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nlmsvc_insert_block(block, NLM_NEVER);
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if (list_empty(&block->b_call.a_args.lock.fl.fl_block)) {
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/* Now add block to block list of the conflicting lock
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if we haven't done so. */
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dprintk("lockd: blocking on this lock.\n");
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posix_block_lock(conflock, &block->b_call.a_args.lock.fl);
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}
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up(&file->f_sema);
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return nlm_lck_blocked;
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}
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/*
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* Test for presence of a conflicting lock.
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*/
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u32
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nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
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struct nlm_lock *conflock)
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{
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struct file_lock *fl;
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dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
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file->f_file->f_dentry->d_inode->i_sb->s_id,
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file->f_file->f_dentry->d_inode->i_ino,
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lock->fl.fl_type,
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(long long)lock->fl.fl_start,
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(long long)lock->fl.fl_end);
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if ((fl = posix_test_lock(file->f_file, &lock->fl)) != NULL) {
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dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
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fl->fl_type, (long long)fl->fl_start,
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(long long)fl->fl_end);
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conflock->caller = "somehost"; /* FIXME */
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conflock->oh.len = 0; /* don't return OH info */
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conflock->fl = *fl;
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return nlm_lck_denied;
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}
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return nlm_granted;
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}
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/*
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* Remove a lock.
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* This implies a CANCEL call: We send a GRANT_MSG, the client replies
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* with a GRANT_RES call which gets lost, and calls UNLOCK immediately
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* afterwards. In this case the block will still be there, and hence
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* must be removed.
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*/
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u32
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nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
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{
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int error;
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dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
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file->f_file->f_dentry->d_inode->i_sb->s_id,
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file->f_file->f_dentry->d_inode->i_ino,
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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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/* First, cancel any lock that might be there */
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nlmsvc_cancel_blocked(file, lock);
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lock->fl.fl_type = F_UNLCK;
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error = posix_lock_file(file->f_file, &lock->fl);
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return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
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}
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/*
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* Cancel a previously blocked request.
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*
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* A cancel request always overrides any grant that may currently
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* be in progress.
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* The calling procedure must check whether the file can be closed.
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*/
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u32
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nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
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{
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struct nlm_block *block;
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dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
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file->f_file->f_dentry->d_inode->i_sb->s_id,
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file->f_file->f_dentry->d_inode->i_ino,
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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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down(&file->f_sema);
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if ((block = nlmsvc_lookup_block(file, lock, 1)) != NULL)
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nlmsvc_delete_block(block, 1);
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up(&file->f_sema);
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return nlm_granted;
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}
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/*
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* Unblock a blocked lock request. This is a callback invoked from the
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* VFS layer when a lock on which we blocked is removed.
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*
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* This function doesn't grant the blocked lock instantly, but rather moves
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* the block to the head of nlm_blocked where it can be picked up by lockd.
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*/
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static void
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nlmsvc_notify_blocked(struct file_lock *fl)
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{
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struct nlm_block **bp, *block;
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dprintk("lockd: VFS unblock notification for block %p\n", fl);
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for (bp = &nlm_blocked; (block = *bp) != 0; bp = &block->b_next) {
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if (nlm_compare_locks(&block->b_call.a_args.lock.fl, fl)) {
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nlmsvc_insert_block(block, 0);
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svc_wake_up(block->b_daemon);
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return;
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}
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}
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printk(KERN_WARNING "lockd: notification for unknown block!\n");
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}
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static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
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{
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return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
|
|
}
|
|
|
|
struct lock_manager_operations nlmsvc_lock_operations = {
|
|
.fl_compare_owner = nlmsvc_same_owner,
|
|
.fl_notify = nlmsvc_notify_blocked,
|
|
};
|
|
|
|
/*
|
|
* 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;
|
|
struct file_lock *conflock;
|
|
int error;
|
|
|
|
dprintk("lockd: grant blocked lock %p\n", block);
|
|
|
|
/* First thing is lock the file */
|
|
down(&file->f_sema);
|
|
|
|
/* Unlink block request from list */
|
|
nlmsvc_remove_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 */
|
|
if ((conflock = posix_test_lock(file->f_file, &lock->fl)) != NULL) {
|
|
/* Bummer, we blocked again */
|
|
dprintk("lockd: lock still blocked\n");
|
|
nlmsvc_insert_block(block, NLM_NEVER);
|
|
posix_block_lock(conflock, &lock->fl);
|
|
up(&file->f_sema);
|
|
return;
|
|
}
|
|
|
|
/* Alright, no conflicting lock. Now lock it for real. If the
|
|
* following yields an error, this is most probably due to low
|
|
* memory. Retry the lock in a few seconds.
|
|
*/
|
|
if ((error = posix_lock_file(file->f_file, &lock->fl)) < 0) {
|
|
printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
|
|
-error, __FUNCTION__);
|
|
nlmsvc_insert_block(block, 10 * HZ);
|
|
up(&file->f_sema);
|
|
return;
|
|
}
|
|
|
|
callback:
|
|
/* Lock was granted by VFS. */
|
|
dprintk("lockd: GRANTing blocked lock.\n");
|
|
block->b_granted = 1;
|
|
block->b_incall = 1;
|
|
|
|
/* Schedule next grant callback in 30 seconds */
|
|
nlmsvc_insert_block(block, 30 * HZ);
|
|
|
|
/* Call the client */
|
|
nlm_get_host(block->b_call.a_host);
|
|
if (nlmsvc_async_call(&block->b_call, NLMPROC_GRANTED_MSG,
|
|
nlmsvc_grant_callback) < 0)
|
|
nlm_release_host(block->b_call.a_host);
|
|
up(&file->f_sema);
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
struct nlm_rqst *call = (struct nlm_rqst *) task->tk_calldata;
|
|
struct nlm_block *block;
|
|
unsigned long timeout;
|
|
struct sockaddr_in *peer_addr = RPC_PEERADDR(task->tk_client);
|
|
|
|
dprintk("lockd: GRANT_MSG RPC callback\n");
|
|
dprintk("callback: looking for cookie %s, host (%u.%u.%u.%u)\n",
|
|
nlmdbg_cookie2a(&call->a_args.cookie),
|
|
NIPQUAD(peer_addr->sin_addr.s_addr));
|
|
if (!(block = nlmsvc_find_block(&call->a_args.cookie, peer_addr))) {
|
|
dprintk("lockd: no block for cookie %s, host (%u.%u.%u.%u)\n",
|
|
nlmdbg_cookie2a(&call->a_args.cookie),
|
|
NIPQUAD(peer_addr->sin_addr.s_addr));
|
|
return;
|
|
}
|
|
|
|
/* 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 if (block->b_done) {
|
|
/* Block already removed, kill it for real */
|
|
timeout = 0;
|
|
} else {
|
|
/* Call was successful, now wait for client callback */
|
|
timeout = 60 * HZ;
|
|
}
|
|
nlmsvc_insert_block(block, timeout);
|
|
svc_wake_up(block->b_daemon);
|
|
block->b_incall = 0;
|
|
|
|
nlm_release_host(call->a_host);
|
|
}
|
|
|
|
/*
|
|
* We received a GRANT_RES callback. Try to find the corresponding
|
|
* block.
|
|
*/
|
|
void
|
|
nlmsvc_grant_reply(struct svc_rqst *rqstp, struct nlm_cookie *cookie, u32 status)
|
|
{
|
|
struct nlm_block *block;
|
|
struct nlm_file *file;
|
|
|
|
dprintk("grant_reply: looking for cookie %x, host (%08x), s=%d \n",
|
|
*(unsigned int *)(cookie->data),
|
|
ntohl(rqstp->rq_addr.sin_addr.s_addr), status);
|
|
if (!(block = nlmsvc_find_block(cookie, &rqstp->rq_addr)))
|
|
return;
|
|
file = block->b_file;
|
|
|
|
file->f_count++;
|
|
down(&file->f_sema);
|
|
if ((block = nlmsvc_find_block(cookie,&rqstp->rq_addr)) != NULL) {
|
|
if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
|
|
/* Try again in a couple of seconds */
|
|
nlmsvc_insert_block(block, 10 * HZ);
|
|
block = NULL;
|
|
} else {
|
|
/* Lock is now held by client, or has been rejected.
|
|
* In both cases, the block should be removed. */
|
|
up(&file->f_sema);
|
|
if (status == NLM_LCK_GRANTED)
|
|
nlmsvc_delete_block(block, 0);
|
|
else
|
|
nlmsvc_delete_block(block, 1);
|
|
}
|
|
}
|
|
if (!block)
|
|
up(&file->f_sema);
|
|
nlm_release_file(file);
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
struct nlm_block *block;
|
|
|
|
dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
|
|
nlm_blocked,
|
|
nlm_blocked? nlm_blocked->b_when : 0);
|
|
while ((block = nlm_blocked) != 0) {
|
|
if (block->b_when == NLM_NEVER)
|
|
break;
|
|
if (time_after(block->b_when,jiffies))
|
|
break;
|
|
dprintk("nlmsvc_retry_blocked(%p, when=%ld, done=%d)\n",
|
|
block, block->b_when, block->b_done);
|
|
if (block->b_done)
|
|
nlmsvc_delete_block(block, 0);
|
|
else
|
|
nlmsvc_grant_blocked(block);
|
|
}
|
|
|
|
if ((block = nlm_blocked) && block->b_when != NLM_NEVER)
|
|
return (block->b_when - jiffies);
|
|
|
|
return MAX_SCHEDULE_TIMEOUT;
|
|
}
|