Hi,
This is another problem report on posix lock.
The nfsd may handle the lock information incorrectly if new lock is
contiguous to old one. I think both 2.6 and 2.4 kernel have this bug.
The following is a sample program to produce the circumstance.
fd = open("file_on_nfs_2", O_RDWR | O_CREAT, 0644);
memset(&lck, 0, sizeof(lck));
lck.l_type = F_WRLCK;
switch (child = fork()) {
case 0:
lck.l_start = 0; lck.l_len = 1; fcntl(fd, F_SETLK, &lck);
sleep(1);
lck.l_start = 1; lck.l_len = 1; fcntl(fd, F_SETLKW, &lck);
_exit(0);
default:
lck.l_start = 1; lck.l_len = 1; fcntl(fd, F_SETLK, &lck);
sleep(2); close(fd);
printf("waiting...\n");
// sleep(1); kill(chiled, SIGINT);
wait(NULL);
break;
}
All version of linux requires time to grant the lock, but on older
kernel the lock is leaked if it is signaled while waiting the grant.
I think it is caused by a miss-calling of posix_lock_file() in nfsd.
posix_lock_file() updates the second argument `request' as you know,
but it seems that nfsd gives no care about that.
Here is a patch. It changes nfsd to keep the range of file_lock for
later use. Any comments and feedback are welcome.
Signed-off-by: ASANO Masahiro <[email protected]>
--- linux-2.6.15-rc6/fs/lockd/svclock.c.orig 2005-12-23 20:16:33.000000000 +0900
+++ linux-2.6.15-rc6/fs/lockd/svclock.c 2005-12-23 20:24:13.000000000 +0900
@@ -510,6 +510,7 @@ nlmsvc_grant_blocked(struct nlm_block *b
struct nlm_file *file = block->b_file;
struct nlm_lock *lock = &block->b_call.a_args.lock;
struct file_lock *conflock;
+ struct file_lock tmplck;
int error;
dprintk("lockd: grant blocked lock %p\n", block);
@@ -542,7 +543,8 @@ nlmsvc_grant_blocked(struct nlm_block *b
* following yields an error, this is most probably due to low
* memory. Retry the lock in a few seconds.
*/
- if ((error = posix_lock_file(file->f_file, &lock->fl)) < 0) {
+ tmplck = lock->fl; /* keep the range for later use */
+ if ((error = posix_lock_file(file->f_file, &tmplck)) < 0) {
printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
-error, __FUNCTION__);
nlmsvc_insert_block(block, 10 * HZ);
-
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