PATCH [5/7] Fix posix locking code

From: Trond Myklebust
Date: Sat Aug 14 2004 - 14:43:13 EST

NLM: Thanks to the wonder of CLONE_FILES, the value of
file_lock->fl_owner may live for longer than the pid
of the process that originally created it. Fix NFSv2/v3
client locking code to map file_lock->fl_owner into
a unique 32-bit number or "pseudo-pid".

Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxx>


fs/lockd/clntlock.c | 4 +-
fs/lockd/clntproc.c | 79 ++++++++++++++++++++++++++++++++++++++++++--
fs/lockd/host.c | 18 ++++++----
include/linux/lockd/lockd.h | 17 ++++++++-
include/linux/nfs_fs_i.h | 4 +-
5 files changed, 108 insertions(+), 14 deletions(-)

diff -u --recursive --new-file --show-c-function linux-2.6.8.1-04-fix_lockd/fs/lockd/clntlock.c linux-2.6.8.1-05-nlm_lockowner/fs/lockd/clntlock.c
--- linux-2.6.8.1-04-fix_lockd/fs/lockd/clntlock.c 2004-08-14 14:27:44.000000000 -0400
+++ linux-2.6.8.1-05-nlm_lockowner/fs/lockd/clntlock.c 2004-08-14 14:29:34.000000000 -0400
@@ -146,7 +146,7 @@ void nlmclnt_mark_reclaim(struct nlm_hos
inode = fl->fl_file->f_dentry->d_inode;
if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
continue;
- if (fl->fl_u.nfs_fl.host != host)
+ if (fl->fl_u.nfs_fl.owner->host != host)
continue;
if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
continue;
@@ -215,7 +215,7 @@ restart:
inode = fl->fl_file->f_dentry->d_inode;
if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
continue;
- if (fl->fl_u.nfs_fl.host != host)
+ if (fl->fl_u.nfs_fl.owner->host != host)
continue;
if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
continue;
diff -u --recursive --new-file --show-c-function linux-2.6.8.1-04-fix_lockd/fs/lockd/clntproc.c linux-2.6.8.1-05-nlm_lockowner/fs/lockd/clntproc.c
--- linux-2.6.8.1-04-fix_lockd/fs/lockd/clntproc.c 2004-08-14 14:29:27.000000000 -0400
+++ linux-2.6.8.1-05-nlm_lockowner/fs/lockd/clntproc.c 2004-08-14 14:29:34.000000000 -0400
@@ -42,6 +42,79 @@ static inline void nlmclnt_next_cookie(s
nlm_cookie++;
}

+static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
+{
+ atomic_inc(&lockowner->count);
+ return lockowner;
+}
+
+static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
+{
+ if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
+ return;
+ list_del(&lockowner->list);
+ spin_unlock(&lockowner->host->h_lock);
+ nlm_release_host(lockowner->host);
+ kfree(lockowner);
+}
+
+static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
+{
+ struct nlm_lockowner *lockowner;
+ list_for_each_entry(lockowner, &host->h_lockowners, list) {
+ if (lockowner->pid == pid)
+ return -EBUSY;
+ }
+ return 0;
+}
+
+static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
+{
+ uint32_t res;
+ do {
+ res = host->h_pidcount++;
+ } while (nlm_pidbusy(host, res) < 0);
+ return res;
+}
+
+static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
+{
+ struct nlm_lockowner *lockowner;
+ list_for_each_entry(lockowner, &host->h_lockowners, list) {
+ if (lockowner->owner != owner)
+ continue;
+ return nlm_get_lockowner(lockowner);
+ }
+ return NULL;
+}
+
+static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
+{
+ struct nlm_lockowner *res, *new = NULL;
+
+ spin_lock(&host->h_lock);
+ res = __nlm_find_lockowner(host, owner);
+ if (res == NULL) {
+ spin_unlock(&host->h_lock);
+ new = (struct nlm_lockowner *)kmalloc(sizeof(*new), GFP_KERNEL);
+ spin_lock(&host->h_lock);
+ res = __nlm_find_lockowner(host, owner);
+ if (res == NULL && new != NULL) {
+ res = new;
+ atomic_set(&new->count, 1);
+ new->owner = owner;
+ new->pid = __nlm_alloc_pid(host);
+ new->host = nlm_get_host(host);
+ list_add(&new->list, &host->h_lockowners);
+ new = NULL;
+ }
+ }
+ spin_unlock(&host->h_lock);
+ if (new != NULL)
+ kfree(new);
+ return res;
+}
+
/*
* Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
*/
@@ -418,12 +491,12 @@ nlmclnt_test(struct nlm_rqst *req, struc
static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
{
memcpy(&new->fl_u.nfs_fl, &fl->fl_u.nfs_fl, sizeof(new->fl_u.nfs_fl));
- nlm_get_host(new->fl_u.nfs_fl.host);
+ nlm_get_lockowner(new->fl_u.nfs_fl.owner);
}

static void nlmclnt_locks_release_private(struct file_lock *fl)
{
- nlm_release_host(fl->fl_u.nfs_fl.host);
+ nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
fl->fl_ops = NULL;
}

@@ -437,7 +510,7 @@ static void nlmclnt_locks_init_private(s
BUG_ON(fl->fl_ops != NULL);
fl->fl_u.nfs_fl.state = 0;
fl->fl_u.nfs_fl.flags = 0;
- fl->fl_u.nfs_fl.host = nlm_get_host(host);
+ fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
fl->fl_ops = &nlmclnt_lock_ops;
}

diff -u --recursive --new-file --show-c-function linux-2.6.8.1-04-fix_lockd/fs/lockd/host.c linux-2.6.8.1-05-nlm_lockowner/fs/lockd/host.c
--- linux-2.6.8.1-04-fix_lockd/fs/lockd/host.c 2004-08-14 14:26:44.000000000 -0400
+++ linux-2.6.8.1-05-nlm_lockowner/fs/lockd/host.c 2004-08-14 14:29:34.000000000 -0400
@@ -119,13 +119,15 @@ nlm_lookup_host(int server, struct socka
init_MUTEX(&host->h_sema);
host->h_nextrebind = jiffies + NLM_HOST_REBIND;
host->h_expires = jiffies + NLM_HOST_EXPIRE;
- host->h_count = 1;
+ atomic_set(&host->h_count, 1);
init_waitqueue_head(&host->h_gracewait);
host->h_state = 0; /* pseudo NSM state */
host->h_nsmstate = 0; /* real NSM state */
host->h_server = server;
host->h_next = nlm_hosts[hash];
nlm_hosts[hash] = host;
+ INIT_LIST_HEAD(&host->h_lockowners);
+ spin_lock_init(&host->h_lock);

if (++nrhosts > NLM_HOST_MAX)
next_gc = 0;
@@ -235,7 +237,7 @@ struct nlm_host * nlm_get_host(struct nl
{
if (host) {
dprintk("lockd: get host %s\n", host->h_name);
- host->h_count ++;
+ atomic_inc(&host->h_count);
host->h_expires = jiffies + NLM_HOST_EXPIRE;
}
return host;
@@ -246,9 +248,10 @@ struct nlm_host * nlm_get_host(struct nl
*/
void nlm_release_host(struct nlm_host *host)
{
- if (host && host->h_count) {
+ if (host != NULL) {
dprintk("lockd: release host %s\n", host->h_name);
- host->h_count --;
+ atomic_dec(&host->h_count);
+ BUG_ON(atomic_read(&host->h_count) < 0);
}
}

@@ -283,7 +286,7 @@ nlm_shutdown_hosts(void)
for (i = 0; i < NLM_HOST_NRHASH; i++) {
for (host = nlm_hosts[i]; host; host = host->h_next) {
dprintk(" %s (cnt %d use %d exp %ld)\n",
- host->h_name, host->h_count,
+ host->h_name, atomic_read(&host->h_count),
host->h_inuse, host->h_expires);
}
}
@@ -314,10 +317,10 @@ nlm_gc_hosts(void)
for (i = 0; i < NLM_HOST_NRHASH; i++) {
q = &nlm_hosts[i];
while ((host = *q) != NULL) {
- if (host->h_count || host->h_inuse
+ if (atomic_read(&host->h_count) || host->h_inuse
|| time_before(jiffies, host->h_expires)) {
dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
- host->h_name, host->h_count,
+ host->h_name, atomic_read(&host->h_count),
host->h_inuse, host->h_expires);
q = &host->h_next;
continue;
@@ -336,6 +339,7 @@ nlm_gc_hosts(void)
rpc_destroy_client(host->h_rpcclnt);
}
}
+ BUG_ON(!list_empty(&host->h_lockowners));
kfree(host);
nrhosts--;
}
diff -u --recursive --new-file --show-c-function linux-2.6.8.1-04-fix_lockd/include/linux/lockd/lockd.h linux-2.6.8.1-05-nlm_lockowner/include/linux/lockd/lockd.h
--- linux-2.6.8.1-04-fix_lockd/include/linux/lockd/lockd.h 2004-08-14 14:29:27.000000000 -0400
+++ linux-2.6.8.1-05-nlm_lockowner/include/linux/lockd/lockd.h 2004-08-14 14:29:34.000000000 -0400
@@ -52,10 +52,25 @@ struct nlm_host {
wait_queue_head_t h_gracewait; /* wait while reclaiming */
u32 h_state; /* pseudo-state counter */
u32 h_nsmstate; /* true remote NSM state */
- unsigned int h_count; /* reference count */
+ u32 h_pidcount; /* Pseudopids */
+ atomic_t h_count; /* reference count */
struct semaphore h_sema; /* mutex for pmap binding */
unsigned long h_nextrebind; /* next portmap call */
unsigned long h_expires; /* eligible for GC */
+ struct list_head h_lockowners; /* Lockowners for the client */
+ spinlock_t h_lock;
+};
+
+/*
+ * Map an fl_owner_t into a unique 32-bit "pid"
+ */
+struct nlm_lockowner {
+ struct list_head list;
+ atomic_t count;
+
+ struct nlm_host *host;
+ fl_owner_t owner;
+ uint32_t pid;
};

/*
diff -u --recursive --new-file --show-c-function linux-2.6.8.1-04-fix_lockd/include/linux/nfs_fs_i.h linux-2.6.8.1-05-nlm_lockowner/include/linux/nfs_fs_i.h
--- linux-2.6.8.1-04-fix_lockd/include/linux/nfs_fs_i.h 2004-08-14 14:28:02.000000000 -0400
+++ linux-2.6.8.1-05-nlm_lockowner/include/linux/nfs_fs_i.h 2004-08-14 14:29:34.000000000 -0400
@@ -5,13 +5,15 @@
#include <linux/list.h>
#include <linux/nfs.h>

+struct nlm_lockowner;
+
/*
* NFS lock info
*/
struct nfs_lock_info {
u32 state;
u32 flags;
- struct nlm_host *host;
+ struct nlm_lockowner *owner;
};

/*

-
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