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299 lines
7.5 KiB
299 lines
7.5 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* linux/fs/lockd/clntlock.c |
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* |
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* Lock handling for the client side NLM implementation |
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* |
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* Copyright (C) 1996, Olaf Kirch <[email protected]> |
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*/ |
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#include <linux/module.h> |
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#include <linux/types.h> |
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#include <linux/slab.h> |
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#include <linux/time.h> |
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#include <linux/nfs_fs.h> |
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#include <linux/sunrpc/addr.h> |
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#include <linux/sunrpc/svc.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_CLIENT |
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/* |
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* Local function prototypes |
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*/ |
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static int reclaimer(void *ptr); |
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/* |
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* The following functions handle blocking and granting from the |
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* client perspective. |
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*/ |
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/* |
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* This is the representation of a blocked client lock. |
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*/ |
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struct nlm_wait { |
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struct list_head b_list; /* linked list */ |
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wait_queue_head_t b_wait; /* where to wait on */ |
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struct nlm_host * b_host; |
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struct file_lock * b_lock; /* local file lock */ |
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unsigned short b_reclaim; /* got to reclaim lock */ |
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__be32 b_status; /* grant callback status */ |
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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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/** |
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* nlmclnt_init - Set up per-NFS mount point lockd data structures |
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* @nlm_init: pointer to arguments structure |
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* |
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* Returns pointer to an appropriate nlm_host struct, |
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* or an ERR_PTR value. |
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*/ |
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struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init) |
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{ |
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struct nlm_host *host; |
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u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4; |
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int status; |
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status = lockd_up(nlm_init->net, nlm_init->cred); |
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if (status < 0) |
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return ERR_PTR(status); |
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host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen, |
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nlm_init->protocol, nlm_version, |
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nlm_init->hostname, nlm_init->noresvport, |
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nlm_init->net, nlm_init->cred); |
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if (host == NULL) |
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goto out_nohost; |
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if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL) |
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goto out_nobind; |
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host->h_nlmclnt_ops = nlm_init->nlmclnt_ops; |
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return host; |
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out_nobind: |
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nlmclnt_release_host(host); |
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out_nohost: |
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lockd_down(nlm_init->net); |
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return ERR_PTR(-ENOLCK); |
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} |
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EXPORT_SYMBOL_GPL(nlmclnt_init); |
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/** |
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* nlmclnt_done - Release resources allocated by nlmclnt_init() |
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* @host: nlm_host structure reserved by nlmclnt_init() |
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* |
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*/ |
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void nlmclnt_done(struct nlm_host *host) |
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{ |
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struct net *net = host->net; |
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nlmclnt_release_host(host); |
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lockd_down(net); |
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} |
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EXPORT_SYMBOL_GPL(nlmclnt_done); |
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/* |
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* Queue up a lock for blocking so that the GRANTED request can see it |
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*/ |
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struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) |
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{ |
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struct nlm_wait *block; |
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block = kmalloc(sizeof(*block), GFP_KERNEL); |
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if (block != NULL) { |
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block->b_host = host; |
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block->b_lock = fl; |
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init_waitqueue_head(&block->b_wait); |
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block->b_status = nlm_lck_blocked; |
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spin_lock(&nlm_blocked_lock); |
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list_add(&block->b_list, &nlm_blocked); |
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spin_unlock(&nlm_blocked_lock); |
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} |
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return block; |
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} |
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void nlmclnt_finish_block(struct nlm_wait *block) |
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{ |
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if (block == NULL) |
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return; |
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spin_lock(&nlm_blocked_lock); |
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list_del(&block->b_list); |
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spin_unlock(&nlm_blocked_lock); |
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kfree(block); |
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} |
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/* |
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* Block on a lock |
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*/ |
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int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) |
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{ |
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long ret; |
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/* A borken server might ask us to block even if we didn't |
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* request it. Just say no! |
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*/ |
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if (block == NULL) |
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return -EAGAIN; |
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/* Go to sleep waiting for GRANT callback. Some servers seem |
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* to lose callbacks, however, so we're going to poll from |
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* time to time just to make sure. |
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* |
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* For now, the retry frequency is pretty high; normally |
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* a 1 minute timeout would do. See the comment before |
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* nlmclnt_lock for an explanation. |
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*/ |
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ret = wait_event_interruptible_timeout(block->b_wait, |
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block->b_status != nlm_lck_blocked, |
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timeout); |
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if (ret < 0) |
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return -ERESTARTSYS; |
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/* Reset the lock status after a server reboot so we resend */ |
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if (block->b_status == nlm_lck_denied_grace_period) |
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block->b_status = nlm_lck_blocked; |
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req->a_res.status = block->b_status; |
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return 0; |
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} |
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/* |
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* The server lockd has called us back to tell us the lock was granted |
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*/ |
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__be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) |
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{ |
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const struct file_lock *fl = &lock->fl; |
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const struct nfs_fh *fh = &lock->fh; |
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struct nlm_wait *block; |
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__be32 res = nlm_lck_denied; |
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/* |
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* Look up blocked request based on arguments. |
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* Warning: must not use cookie to match it! |
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*/ |
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spin_lock(&nlm_blocked_lock); |
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list_for_each_entry(block, &nlm_blocked, b_list) { |
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struct file_lock *fl_blocked = block->b_lock; |
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if (fl_blocked->fl_start != fl->fl_start) |
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continue; |
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if (fl_blocked->fl_end != fl->fl_end) |
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continue; |
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/* |
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* Careful! The NLM server will return the 32-bit "pid" that |
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* we put on the wire: in this case the lockowner "pid". |
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*/ |
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if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) |
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continue; |
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if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) |
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continue; |
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if (nfs_compare_fh(NFS_FH(locks_inode(fl_blocked->fl_file)), fh) != 0) |
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continue; |
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/* Alright, we found a lock. Set the return status |
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* and wake up the caller |
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*/ |
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block->b_status = nlm_granted; |
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wake_up(&block->b_wait); |
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res = nlm_granted; |
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} |
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spin_unlock(&nlm_blocked_lock); |
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return res; |
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} |
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/* |
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* The following procedures deal with the recovery of locks after a |
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* server crash. |
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*/ |
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/* |
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* Reclaim all locks on server host. We do this by spawning a separate |
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* reclaimer thread. |
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*/ |
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void |
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nlmclnt_recovery(struct nlm_host *host) |
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{ |
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struct task_struct *task; |
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if (!host->h_reclaiming++) { |
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nlm_get_host(host); |
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task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); |
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if (IS_ERR(task)) |
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printk(KERN_ERR "lockd: unable to spawn reclaimer " |
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"thread. Locks for %s won't be reclaimed! " |
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"(%ld)\n", host->h_name, PTR_ERR(task)); |
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} |
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} |
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static int |
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reclaimer(void *ptr) |
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{ |
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struct nlm_host *host = (struct nlm_host *) ptr; |
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struct nlm_wait *block; |
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struct nlm_rqst *req; |
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struct file_lock *fl, *next; |
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u32 nsmstate; |
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struct net *net = host->net; |
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req = kmalloc(sizeof(*req), GFP_KERNEL); |
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if (!req) |
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return 0; |
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allow_signal(SIGKILL); |
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down_write(&host->h_rwsem); |
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lockd_up(net, NULL); /* note: this cannot fail as lockd is already running */ |
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dprintk("lockd: reclaiming locks for host %s\n", host->h_name); |
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restart: |
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nsmstate = host->h_nsmstate; |
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/* Force a portmap getport - the peer's lockd will |
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* most likely end up on a different port. |
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*/ |
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host->h_nextrebind = jiffies; |
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nlm_rebind_host(host); |
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/* First, reclaim all locks that have been granted. */ |
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list_splice_init(&host->h_granted, &host->h_reclaim); |
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list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { |
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list_del_init(&fl->fl_u.nfs_fl.list); |
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/* |
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* sending this thread a SIGKILL will result in any unreclaimed |
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* locks being removed from the h_granted list. This means that |
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* the kernel will not attempt to reclaim them again if a new |
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* reclaimer thread is spawned for this host. |
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*/ |
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if (signalled()) |
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continue; |
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if (nlmclnt_reclaim(host, fl, req) != 0) |
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continue; |
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list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); |
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if (host->h_nsmstate != nsmstate) { |
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/* Argh! The server rebooted again! */ |
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goto restart; |
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} |
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} |
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host->h_reclaiming = 0; |
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up_write(&host->h_rwsem); |
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dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); |
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/* Now, wake up all processes that sleep on a blocked lock */ |
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spin_lock(&nlm_blocked_lock); |
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list_for_each_entry(block, &nlm_blocked, b_list) { |
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if (block->b_host == host) { |
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block->b_status = nlm_lck_denied_grace_period; |
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wake_up(&block->b_wait); |
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} |
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} |
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spin_unlock(&nlm_blocked_lock); |
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/* Release host handle after use */ |
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nlmclnt_release_host(host); |
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lockd_down(net); |
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kfree(req); |
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return 0; |
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}
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