diff options
| -rw-r--r-- | Documentation/filesystems/Locking | 16 | ||||
| -rw-r--r-- | fs/lockd/svclock.c | 12 | ||||
| -rw-r--r-- | fs/locks.c | 12 | ||||
| -rw-r--r-- | include/linux/fs.h | 1 |
4 files changed, 34 insertions, 7 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index c2963a74fbc3..2db7c9e492e9 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -349,6 +349,7 @@ fl_release_private: maybe no ----------------------- lock_manager_operations --------------------------- prototypes: int (*lm_compare_owner)(struct file_lock *, struct file_lock *); + unsigned long (*lm_owner_key)(struct file_lock *); void (*lm_notify)(struct file_lock *); /* unblock callback */ int (*lm_grant)(struct file_lock *, struct file_lock *, int); void (*lm_break)(struct file_lock *); /* break_lease callback */ @@ -358,16 +359,21 @@ locking rules: inode->i_lock file_lock_lock may block lm_compare_owner: yes[1] maybe no +lm_owner_key yes[1] yes no lm_notify: yes yes no lm_grant: no no no lm_break: yes no no lm_change yes no no -[1]: ->lm_compare_owner is generally called with *an* inode->i_lock held. It -may not be the i_lock of the inode for either file_lock being compared! This is -the case with deadlock detection, since the code has to chase down the owners -of locks that may be entirely unrelated to the one on which the lock is being -acquired. When doing a search for deadlocks, the file_lock_lock is also held. +[1]: ->lm_compare_owner and ->lm_owner_key are generally called with +*an* inode->i_lock held. It may not be the i_lock of the inode +associated with either file_lock argument! This is the case with deadlock +detection, since the code has to chase down the owners of locks that may +be entirely unrelated to the one on which the lock is being acquired. +For deadlock detection however, the file_lock_lock is also held. The +fact that these locks are held ensures that the file_locks do not +disappear out from under you while doing the comparison or generating an +owner key. --------------------------- buffer_head ----------------------------------- prototypes: diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index a469098682c4..067778b0ccc9 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -744,8 +744,20 @@ static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2) return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid; } +/* + * Since NLM uses two "keys" for tracking locks, we need to hash them down + * to one for the blocked_hash. Here, we're just xor'ing the host address + * with the pid in order to create a key value for picking a hash bucket. + */ +static unsigned long +nlmsvc_owner_key(struct file_lock *fl) +{ + return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid; +} + const struct lock_manager_operations nlmsvc_lock_operations = { .lm_compare_owner = nlmsvc_same_owner, + .lm_owner_key = nlmsvc_owner_key, .lm_notify = nlmsvc_notify_blocked, .lm_grant = nlmsvc_grant_deferred, }; diff --git a/fs/locks.c b/fs/locks.c index 71d847cbbb63..6242e0b1c69c 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -521,10 +521,18 @@ locks_delete_global_locks(struct file_lock *fl) spin_unlock(&file_lock_lock); } +static unsigned long +posix_owner_key(struct file_lock *fl) +{ + if (fl->fl_lmops && fl->fl_lmops->lm_owner_key) + return fl->fl_lmops->lm_owner_key(fl); + return (unsigned long)fl->fl_owner; +} + static inline void locks_insert_global_blocked(struct file_lock *waiter) { - hash_add(blocked_hash, &waiter->fl_link, (unsigned long)waiter->fl_owner); + hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter)); } static inline void @@ -757,7 +765,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl) { struct file_lock *fl; - hash_for_each_possible(blocked_hash, fl, fl_link, (unsigned long)block_fl->fl_owner) { + hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) { if (posix_same_owner(fl, block_fl)) return fl->fl_next; } diff --git a/include/linux/fs.h b/include/linux/fs.h index fab064a3b65f..a137a73fc1fe 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -908,6 +908,7 @@ struct file_lock_operations { struct lock_manager_operations { int (*lm_compare_owner)(struct file_lock *, struct file_lock *); + unsigned long (*lm_owner_key)(struct file_lock *); void (*lm_notify)(struct file_lock *); /* unblock callback */ int (*lm_grant)(struct file_lock *, struct file_lock *, int); void (*lm_break)(struct file_lock *); |
