diff options
Diffstat (limited to 'kernel/fs/lockd/clntlock.c')
| -rw-r--r-- | kernel/fs/lockd/clntlock.c | 301 |
1 files changed, 301 insertions, 0 deletions
diff --git a/kernel/fs/lockd/clntlock.c b/kernel/fs/lockd/clntlock.c new file mode 100644 index 000000000..41e491b8e --- /dev/null +++ b/kernel/fs/lockd/clntlock.c @@ -0,0 +1,301 @@ +/* + * linux/fs/lockd/clntlock.c + * + * Lock handling for the client side NLM implementation + * + * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de> + */ + +#include <linux/module.h> +#include <linux/types.h> +#include <linux/slab.h> +#include <linux/time.h> +#include <linux/nfs_fs.h> +#include <linux/sunrpc/addr.h> +#include <linux/sunrpc/svc.h> +#include <linux/lockd/lockd.h> +#include <linux/kthread.h> + +#define NLMDBG_FACILITY NLMDBG_CLIENT + +/* + * Local function prototypes + */ +static int reclaimer(void *ptr); + +/* + * The following functions handle blocking and granting from the + * client perspective. + */ + +/* + * This is the representation of a blocked client lock. + */ +struct nlm_wait { + struct list_head b_list; /* linked list */ + wait_queue_head_t b_wait; /* where to wait on */ + struct nlm_host * b_host; + struct file_lock * b_lock; /* local file lock */ + unsigned short b_reclaim; /* got to reclaim lock */ + __be32 b_status; /* grant callback status */ +}; + +static LIST_HEAD(nlm_blocked); +static DEFINE_SPINLOCK(nlm_blocked_lock); + +/** + * nlmclnt_init - Set up per-NFS mount point lockd data structures + * @nlm_init: pointer to arguments structure + * + * Returns pointer to an appropriate nlm_host struct, + * or an ERR_PTR value. + */ +struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init) +{ + struct nlm_host *host; + u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4; + int status; + + status = lockd_up(nlm_init->net); + if (status < 0) + return ERR_PTR(status); + + host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen, + nlm_init->protocol, nlm_version, + nlm_init->hostname, nlm_init->noresvport, + nlm_init->net); + if (host == NULL) + goto out_nohost; + if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL) + goto out_nobind; + + return host; +out_nobind: + nlmclnt_release_host(host); +out_nohost: + lockd_down(nlm_init->net); + return ERR_PTR(-ENOLCK); +} +EXPORT_SYMBOL_GPL(nlmclnt_init); + +/** + * nlmclnt_done - Release resources allocated by nlmclnt_init() + * @host: nlm_host structure reserved by nlmclnt_init() + * + */ +void nlmclnt_done(struct nlm_host *host) +{ + struct net *net = host->net; + + nlmclnt_release_host(host); + lockd_down(net); +} +EXPORT_SYMBOL_GPL(nlmclnt_done); + +/* + * Queue up a lock for blocking so that the GRANTED request can see it + */ +struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) +{ + struct nlm_wait *block; + + block = kmalloc(sizeof(*block), GFP_KERNEL); + if (block != NULL) { + block->b_host = host; + block->b_lock = fl; + init_waitqueue_head(&block->b_wait); + block->b_status = nlm_lck_blocked; + + spin_lock(&nlm_blocked_lock); + list_add(&block->b_list, &nlm_blocked); + spin_unlock(&nlm_blocked_lock); + } + return block; +} + +void nlmclnt_finish_block(struct nlm_wait *block) +{ + if (block == NULL) + return; + spin_lock(&nlm_blocked_lock); + list_del(&block->b_list); + spin_unlock(&nlm_blocked_lock); + kfree(block); +} + +/* + * Block on a lock + */ +int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) +{ + long ret; + + /* A borken server might ask us to block even if we didn't + * request it. Just say no! + */ + if (block == NULL) + return -EAGAIN; + + /* Go to sleep waiting for GRANT callback. Some servers seem + * to lose callbacks, however, so we're going to poll from + * time to time just to make sure. + * + * For now, the retry frequency is pretty high; normally + * a 1 minute timeout would do. See the comment before + * nlmclnt_lock for an explanation. + */ + ret = wait_event_interruptible_timeout(block->b_wait, + block->b_status != nlm_lck_blocked, + timeout); + if (ret < 0) + return -ERESTARTSYS; + /* Reset the lock status after a server reboot so we resend */ + if (block->b_status == nlm_lck_denied_grace_period) + block->b_status = nlm_lck_blocked; + req->a_res.status = block->b_status; + return 0; +} + +/* + * The server lockd has called us back to tell us the lock was granted + */ +__be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) +{ + const struct file_lock *fl = &lock->fl; + const struct nfs_fh *fh = &lock->fh; + struct nlm_wait *block; + __be32 res = nlm_lck_denied; + + /* + * Look up blocked request based on arguments. + * Warning: must not use cookie to match it! + */ + spin_lock(&nlm_blocked_lock); + list_for_each_entry(block, &nlm_blocked, b_list) { + struct file_lock *fl_blocked = block->b_lock; + + if (fl_blocked->fl_start != fl->fl_start) + continue; + if (fl_blocked->fl_end != fl->fl_end) + continue; + /* + * Careful! The NLM server will return the 32-bit "pid" that + * we put on the wire: in this case the lockowner "pid". + */ + if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) + continue; + if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) + continue; + if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)) ,fh) != 0) + continue; + /* Alright, we found a lock. Set the return status + * and wake up the caller + */ + block->b_status = nlm_granted; + wake_up(&block->b_wait); + res = nlm_granted; + } + spin_unlock(&nlm_blocked_lock); + return res; +} + +/* + * The following procedures deal with the recovery of locks after a + * server crash. + */ + +/* + * Reclaim all locks on server host. We do this by spawning a separate + * reclaimer thread. + */ +void +nlmclnt_recovery(struct nlm_host *host) +{ + struct task_struct *task; + + if (!host->h_reclaiming++) { + nlm_get_host(host); + task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); + if (IS_ERR(task)) + printk(KERN_ERR "lockd: unable to spawn reclaimer " + "thread. Locks for %s won't be reclaimed! " + "(%ld)\n", host->h_name, PTR_ERR(task)); + } +} + +static int +reclaimer(void *ptr) +{ + struct nlm_host *host = (struct nlm_host *) ptr; + struct nlm_wait *block; + struct nlm_rqst *req; + struct file_lock *fl, *next; + u32 nsmstate; + struct net *net = host->net; + + req = kmalloc(sizeof(*req), GFP_KERNEL); + if (!req) { + printk(KERN_ERR "lockd: reclaimer unable to alloc memory." + " Locks for %s won't be reclaimed!\n", + host->h_name); + return 0; + } + + allow_signal(SIGKILL); + + down_write(&host->h_rwsem); + lockd_up(net); /* note: this cannot fail as lockd is already running */ + + dprintk("lockd: reclaiming locks for host %s\n", host->h_name); + +restart: + nsmstate = host->h_nsmstate; + + /* Force a portmap getport - the peer's lockd will + * most likely end up on a different port. + */ + host->h_nextrebind = jiffies; + nlm_rebind_host(host); + + /* First, reclaim all locks that have been granted. */ + list_splice_init(&host->h_granted, &host->h_reclaim); + list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { + list_del_init(&fl->fl_u.nfs_fl.list); + + /* + * sending this thread a SIGKILL will result in any unreclaimed + * locks being removed from the h_granted list. This means that + * the kernel will not attempt to reclaim them again if a new + * reclaimer thread is spawned for this host. + */ + if (signalled()) + continue; + if (nlmclnt_reclaim(host, fl, req) != 0) + continue; + list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); + if (host->h_nsmstate != nsmstate) { + /* Argh! The server rebooted again! */ + goto restart; + } + } + + host->h_reclaiming = 0; + up_write(&host->h_rwsem); + dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); + + /* Now, wake up all processes that sleep on a blocked lock */ + spin_lock(&nlm_blocked_lock); + list_for_each_entry(block, &nlm_blocked, b_list) { + if (block->b_host == host) { + block->b_status = nlm_lck_denied_grace_period; + wake_up(&block->b_wait); + } + } + spin_unlock(&nlm_blocked_lock); + + /* Release host handle after use */ + nlmclnt_release_host(host); + lockd_down(net); + kfree(req); + return 0; +} |