linux/fs/lockd/svcsubs.c
Wendy Cheng 4373ea84c8 lockd: unlock lockd locks associated with a given server ip
For high-availability NFS service, we generally need to be able to drop
file locks held on the exported filesystem before moving clients to a
new server.  Currently the only way to do that is by shutting down lockd
entirely, which is often undesireable (for example, if you want to
continue exporting other filesystems).

This patch allows the administrator to release all locks held by clients
accessing the client through a given server ip address, by echoing that
address to a new file, /proc/fs/nfsd/unlock_ip, as in:

shell> echo 10.1.1.2 > /proc/fs/nfsd/unlock_ip

The expected sequence of events can be:
1. Tear down the IP address
2. Unexport the path
3. Write IP to /proc/fs/nfsd/unlock_ip to unlock files
4. Signal peer to begin take-over.

For now we only support IPv4 addresses and NFSv2/v3 (NFSv4 locks are not
affected).

Also, if unmounting the filesystem is required, we assume at step 3 that
clients using the given server ip are the only clients holding locks on
the given filesystem; otherwise, an additional patch is required to
allow revoking all locks held by lockd on a given filesystem.

Signed-off-by: S. Wendy Cheng <wcheng@redhat.com>
Cc: Lon Hohberger  <lhh@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

 fs/lockd/svcsubs.c          |   66 +++++++++++++++++++++++++++++++++++++++-----
 fs/nfsd/nfsctl.c            |   65 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/lockd/lockd.h |    7 ++++
 3 files changed, 131 insertions(+), 7 deletions(-)
2008-04-25 13:00:10 -04:00

399 lines
8.8 KiB
C

/*
* linux/fs/lockd/svcsubs.c
*
* Various support routines for the NLM server.
*
* Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
*/
#include <linux/types.h>
#include <linux/string.h>
#include <linux/time.h>
#include <linux/in.h>
#include <linux/mutex.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfsd/nfsfh.h>
#include <linux/nfsd/export.h>
#include <linux/lockd/lockd.h>
#include <linux/lockd/share.h>
#include <linux/lockd/sm_inter.h>
#include <linux/module.h>
#include <linux/mount.h>
#define NLMDBG_FACILITY NLMDBG_SVCSUBS
/*
* Global file hash table
*/
#define FILE_HASH_BITS 7
#define FILE_NRHASH (1<<FILE_HASH_BITS)
static struct hlist_head nlm_files[FILE_NRHASH];
static DEFINE_MUTEX(nlm_file_mutex);
#ifdef NFSD_DEBUG
static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
{
u32 *fhp = (u32*)f->data;
/* print the first 32 bytes of the fh */
dprintk("lockd: %s (%08x %08x %08x %08x %08x %08x %08x %08x)\n",
msg, fhp[0], fhp[1], fhp[2], fhp[3],
fhp[4], fhp[5], fhp[6], fhp[7]);
}
static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
{
struct inode *inode = file->f_file->f_path.dentry->d_inode;
dprintk("lockd: %s %s/%ld\n",
msg, inode->i_sb->s_id, inode->i_ino);
}
#else
static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
{
return;
}
static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
{
return;
}
#endif
static inline unsigned int file_hash(struct nfs_fh *f)
{
unsigned int tmp=0;
int i;
for (i=0; i<NFS2_FHSIZE;i++)
tmp += f->data[i];
return tmp & (FILE_NRHASH - 1);
}
/*
* Lookup file info. If it doesn't exist, create a file info struct
* and open a (VFS) file for the given inode.
*
* FIXME:
* Note that we open the file O_RDONLY even when creating write locks.
* This is not quite right, but for now, we assume the client performs
* the proper R/W checking.
*/
__be32
nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
struct nfs_fh *f)
{
struct hlist_node *pos;
struct nlm_file *file;
unsigned int hash;
__be32 nfserr;
nlm_debug_print_fh("nlm_lookup_file", f);
hash = file_hash(f);
/* Lock file table */
mutex_lock(&nlm_file_mutex);
hlist_for_each_entry(file, pos, &nlm_files[hash], f_list)
if (!nfs_compare_fh(&file->f_handle, f))
goto found;
nlm_debug_print_fh("creating file for", f);
nfserr = nlm_lck_denied_nolocks;
file = kzalloc(sizeof(*file), GFP_KERNEL);
if (!file)
goto out_unlock;
memcpy(&file->f_handle, f, sizeof(struct nfs_fh));
mutex_init(&file->f_mutex);
INIT_HLIST_NODE(&file->f_list);
INIT_LIST_HEAD(&file->f_blocks);
/* Open the file. Note that this must not sleep for too long, else
* we would lock up lockd:-) So no NFS re-exports, folks.
*
* We have to make sure we have the right credential to open
* the file.
*/
if ((nfserr = nlmsvc_ops->fopen(rqstp, f, &file->f_file)) != 0) {
dprintk("lockd: open failed (error %d)\n", nfserr);
goto out_free;
}
hlist_add_head(&file->f_list, &nlm_files[hash]);
found:
dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
*result = file;
file->f_count++;
nfserr = 0;
out_unlock:
mutex_unlock(&nlm_file_mutex);
return nfserr;
out_free:
kfree(file);
goto out_unlock;
}
/*
* Delete a file after having released all locks, blocks and shares
*/
static inline void
nlm_delete_file(struct nlm_file *file)
{
nlm_debug_print_file("closing file", file);
if (!hlist_unhashed(&file->f_list)) {
hlist_del(&file->f_list);
nlmsvc_ops->fclose(file->f_file);
kfree(file);
} else {
printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
}
}
/*
* Loop over all locks on the given file and perform the specified
* action.
*/
static int
nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
nlm_host_match_fn_t match)
{
struct inode *inode = nlmsvc_file_inode(file);
struct file_lock *fl;
struct nlm_host *lockhost;
again:
file->f_locks = 0;
for (fl = inode->i_flock; fl; fl = fl->fl_next) {
if (fl->fl_lmops != &nlmsvc_lock_operations)
continue;
/* update current lock count */
file->f_locks++;
lockhost = (struct nlm_host *) fl->fl_owner;
if (match(lockhost, host)) {
struct file_lock lock = *fl;
lock.fl_type = F_UNLCK;
lock.fl_start = 0;
lock.fl_end = OFFSET_MAX;
if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {
printk("lockd: unlock failure in %s:%d\n",
__FILE__, __LINE__);
return 1;
}
goto again;
}
}
return 0;
}
/*
* Inspect a single file
*/
static inline int
nlm_inspect_file(struct nlm_host *host, struct nlm_file *file, nlm_host_match_fn_t match)
{
nlmsvc_traverse_blocks(host, file, match);
nlmsvc_traverse_shares(host, file, match);
return nlm_traverse_locks(host, file, match);
}
/*
* Quick check whether there are still any locks, blocks or
* shares on a given file.
*/
static inline int
nlm_file_inuse(struct nlm_file *file)
{
struct inode *inode = nlmsvc_file_inode(file);
struct file_lock *fl;
if (file->f_count || !list_empty(&file->f_blocks) || file->f_shares)
return 1;
for (fl = inode->i_flock; fl; fl = fl->fl_next) {
if (fl->fl_lmops == &nlmsvc_lock_operations)
return 1;
}
file->f_locks = 0;
return 0;
}
/*
* Loop over all files in the file table.
*/
static int
nlm_traverse_files(void *data, nlm_host_match_fn_t match)
{
struct hlist_node *pos, *next;
struct nlm_file *file;
int i, ret = 0;
mutex_lock(&nlm_file_mutex);
for (i = 0; i < FILE_NRHASH; i++) {
hlist_for_each_entry_safe(file, pos, next, &nlm_files[i], f_list) {
file->f_count++;
mutex_unlock(&nlm_file_mutex);
/* Traverse locks, blocks and shares of this file
* and update file->f_locks count */
if (nlm_inspect_file(data, file, match))
ret = 1;
mutex_lock(&nlm_file_mutex);
file->f_count--;
/* No more references to this file. Let go of it. */
if (list_empty(&file->f_blocks) && !file->f_locks
&& !file->f_shares && !file->f_count) {
hlist_del(&file->f_list);
nlmsvc_ops->fclose(file->f_file);
kfree(file);
}
}
}
mutex_unlock(&nlm_file_mutex);
return ret;
}
/*
* Release file. If there are no more remote locks on this file,
* close it and free the handle.
*
* Note that we can't do proper reference counting without major
* contortions because the code in fs/locks.c creates, deletes and
* splits locks without notification. Our only way is to walk the
* entire lock list each time we remove a lock.
*/
void
nlm_release_file(struct nlm_file *file)
{
dprintk("lockd: nlm_release_file(%p, ct = %d)\n",
file, file->f_count);
/* Lock file table */
mutex_lock(&nlm_file_mutex);
/* If there are no more locks etc, delete the file */
if (--file->f_count == 0 && !nlm_file_inuse(file))
nlm_delete_file(file);
mutex_unlock(&nlm_file_mutex);
}
/*
* Helpers function for resource traversal
*
* nlmsvc_mark_host:
* used by the garbage collector; simply sets h_inuse.
* Always returns 0.
*
* nlmsvc_same_host:
* returns 1 iff the two hosts match. Used to release
* all resources bound to a specific host.
*
* nlmsvc_is_client:
* returns 1 iff the host is a client.
* Used by nlmsvc_invalidate_all
*/
static int
nlmsvc_mark_host(void *data, struct nlm_host *dummy)
{
struct nlm_host *host = data;
host->h_inuse = 1;
return 0;
}
static int
nlmsvc_same_host(void *data, struct nlm_host *other)
{
struct nlm_host *host = data;
return host == other;
}
static int
nlmsvc_is_client(void *data, struct nlm_host *dummy)
{
struct nlm_host *host = data;
if (host->h_server) {
/* we are destroying locks even though the client
* hasn't asked us too, so don't unmonitor the
* client
*/
if (host->h_nsmhandle)
host->h_nsmhandle->sm_sticky = 1;
return 1;
} else
return 0;
}
/*
* Mark all hosts that still hold resources
*/
void
nlmsvc_mark_resources(void)
{
dprintk("lockd: nlmsvc_mark_resources\n");
nlm_traverse_files(NULL, nlmsvc_mark_host);
}
/*
* Release all resources held by the given client
*/
void
nlmsvc_free_host_resources(struct nlm_host *host)
{
dprintk("lockd: nlmsvc_free_host_resources\n");
if (nlm_traverse_files(host, nlmsvc_same_host)) {
printk(KERN_WARNING
"lockd: couldn't remove all locks held by %s\n",
host->h_name);
BUG();
}
}
/*
* Remove all locks held for clients
*/
void
nlmsvc_invalidate_all(void)
{
/* Release all locks held by NFS clients.
* Previously, the code would call
* nlmsvc_free_host_resources for each client in
* turn, which is about as inefficient as it gets.
* Now we just do it once in nlm_traverse_files.
*/
nlm_traverse_files(NULL, nlmsvc_is_client);
}
static int
nlmsvc_match_ip(void *datap, struct nlm_host *host)
{
__be32 *server_addr = datap;
return host->h_saddr.sin_addr.s_addr == *server_addr;
}
int
nlmsvc_unlock_all_by_ip(__be32 server_addr)
{
int ret;
ret = nlm_traverse_files(&server_addr, nlmsvc_match_ip);
return ret ? -EIO : 0;
}
EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_ip);