kernel-ark/fs/lockd/clntlock.c
Trond Myklebust 5ac5f9d1ce [PATCH] NLM: Fix the NLM_GRANTED callback checks
If 2 threads attached to the same process are blocking on different locks on
different files (maybe even on different servers) but have the same lock
arguments (i.e.  same offset+length - actually quite common, since most
processes try to lock the entire file) then the first GRANTED call that wakes
one up will also wake the other.

Currently when the NLM_GRANTED callback comes in, lockd walks the list of
blocked locks in search of a match to the lock that the NLM server has
granted.  Although it checks the lock pid, start and end, it fails to check
the filehandle and the server address.

By checking the filehandle and server IP address, we ensure that this only
happens if the locks truly are referencing the same file.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-14 16:09:34 -08:00

268 lines
6.3 KiB
C

/*
* 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/time.h>
#include <linux/nfs_fs.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.h>
#include <linux/smp_lock.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 */
u32 b_status; /* grant callback status */
};
static LIST_HEAD(nlm_blocked);
/*
* Queue up a lock for blocking so that the GRANTED request can see it
*/
int nlmclnt_prepare_block(struct nlm_rqst *req, struct nlm_host *host, struct file_lock *fl)
{
struct nlm_wait *block;
BUG_ON(req->a_block != NULL);
block = kmalloc(sizeof(*block), GFP_KERNEL);
if (block == NULL)
return -ENOMEM;
block->b_host = host;
block->b_lock = fl;
init_waitqueue_head(&block->b_wait);
block->b_status = NLM_LCK_BLOCKED;
list_add(&block->b_list, &nlm_blocked);
req->a_block = block;
return 0;
}
void nlmclnt_finish_block(struct nlm_rqst *req)
{
struct nlm_wait *block = req->a_block;
if (block == NULL)
return;
req->a_block = NULL;
list_del(&block->b_list);
kfree(block);
}
/*
* Block on a lock
*/
long nlmclnt_block(struct nlm_rqst *req, long timeout)
{
struct nlm_wait *block = req->a_block;
long ret;
/* A borken server might ask us to block even if we didn't
* request it. Just say no!
*/
if (!req->a_args.block)
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 (block->b_status != NLM_LCK_BLOCKED) {
req->a_res.status = block->b_status;
block->b_status = NLM_LCK_BLOCKED;
}
return ret;
}
/*
* The server lockd has called us back to tell us the lock was granted
*/
u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
{
const struct file_lock *fl = &lock->fl;
const struct nfs_fh *fh = &lock->fh;
struct nlm_wait *block;
u32 res = nlm_lck_denied;
/*
* Look up blocked request based on arguments.
* Warning: must not use cookie to match it!
*/
list_for_each_entry(block, &nlm_blocked, b_list) {
struct file_lock *fl_blocked = block->b_lock;
if (!nlm_compare_locks(fl_blocked, fl))
continue;
if (!nlm_cmp_addr(&block->b_host->h_addr, addr))
continue;
if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_dentry->d_inode) ,fh) != 0)
continue;
/* Alright, we found a lock. Set the return status
* and wake up the caller
*/
block->b_status = NLM_LCK_GRANTED;
wake_up(&block->b_wait);
res = nlm_granted;
}
return res;
}
/*
* The following procedures deal with the recovery of locks after a
* server crash.
*/
/*
* Mark the locks for reclaiming.
* FIXME: In 2.5 we don't want to iterate through any global file_lock_list.
* Maintain NLM lock reclaiming lists in the nlm_host instead.
*/
static
void nlmclnt_mark_reclaim(struct nlm_host *host)
{
struct file_lock *fl;
struct inode *inode;
struct list_head *tmp;
list_for_each(tmp, &file_lock_list) {
fl = list_entry(tmp, struct file_lock, fl_link);
inode = fl->fl_file->f_dentry->d_inode;
if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
continue;
if (fl->fl_u.nfs_fl.owner == NULL)
continue;
if (fl->fl_u.nfs_fl.owner->host != host)
continue;
if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
continue;
fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM;
}
}
/*
* Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
* that we mark locks for reclaiming, and that we bump the pseudo NSM state.
*/
static inline
void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
{
host->h_monitored = 0;
host->h_nsmstate = newstate;
host->h_state++;
host->h_nextrebind = 0;
nlm_rebind_host(host);
nlmclnt_mark_reclaim(host);
dprintk("NLM: reclaiming locks for host %s", host->h_name);
}
/*
* Reclaim all locks on server host. We do this by spawning a separate
* reclaimer thread.
*/
void
nlmclnt_recovery(struct nlm_host *host, u32 newstate)
{
if (host->h_reclaiming++) {
if (host->h_nsmstate == newstate)
return;
nlmclnt_prepare_reclaim(host, newstate);
} else {
nlmclnt_prepare_reclaim(host, newstate);
nlm_get_host(host);
__module_get(THIS_MODULE);
if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
module_put(THIS_MODULE);
}
}
static int
reclaimer(void *ptr)
{
struct nlm_host *host = (struct nlm_host *) ptr;
struct nlm_wait *block;
struct list_head *tmp;
struct file_lock *fl;
struct inode *inode;
daemonize("%s-reclaim", host->h_name);
allow_signal(SIGKILL);
/* This one ensures that our parent doesn't terminate while the
* reclaim is in progress */
lock_kernel();
lockd_up();
/* First, reclaim all locks that have been marked. */
restart:
list_for_each(tmp, &file_lock_list) {
fl = list_entry(tmp, struct file_lock, fl_link);
inode = fl->fl_file->f_dentry->d_inode;
if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
continue;
if (fl->fl_u.nfs_fl.owner == NULL)
continue;
if (fl->fl_u.nfs_fl.owner->host != host)
continue;
if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
continue;
fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM;
nlmclnt_reclaim(host, fl);
if (signalled())
break;
goto restart;
}
host->h_reclaiming = 0;
/* Now, wake up all processes that sleep on a 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);
}
}
/* Release host handle after use */
nlm_release_host(host);
lockd_down();
unlock_kernel();
module_put_and_exit(0);
}