return total_objects;
}
+static void destroy_super_work(struct work_struct *work)
+{
+ struct super_block *s = container_of(work, struct super_block,
+ destroy_work);
+ int i;
+
+ for (i = 0; i < SB_FREEZE_LEVELS; i++)
+ percpu_free_rwsem(&s->s_writers.rw_sem[i]);
+ kfree(s);
+}
+
+static void destroy_super_rcu(struct rcu_head *head)
+{
+ struct super_block *s = container_of(head, struct super_block, rcu);
+ INIT_WORK(&s->destroy_work, destroy_super_work);
+ schedule_work(&s->destroy_work);
+}
+
/**
* destroy_super - frees a superblock
* @s: superblock to free
*/
static void destroy_super(struct super_block *s)
{
- int i;
list_lru_destroy(&s->s_dentry_lru);
list_lru_destroy(&s->s_inode_lru);
- for (i = 0; i < SB_FREEZE_LEVELS; i++)
- percpu_counter_destroy(&s->s_writers.counter[i]);
security_sb_free(s);
WARN_ON(!list_empty(&s->s_mounts));
kfree(s->s_subtype);
kfree(s->s_options);
- kfree_rcu(s, rcu);
+ call_rcu(&s->rcu, destroy_super_rcu);
}
/**
goto fail;
for (i = 0; i < SB_FREEZE_LEVELS; i++) {
- if (percpu_counter_init(&s->s_writers.counter[i], 0,
- GFP_KERNEL) < 0)
+ if (__percpu_init_rwsem(&s->s_writers.rw_sem[i],
+ sb_writers_name[i],
+ &type->s_writers_key[i]))
goto fail;
- lockdep_init_map(&s->s_writers.lock_map[i], sb_writers_name[i],
- &type->s_writers_key[i], 0);
}
- init_waitqueue_head(&s->s_writers.wait);
init_waitqueue_head(&s->s_writers.wait_unfrozen);
s->s_bdi = &noop_backing_dev_info;
s->s_flags = flags;
INIT_HLIST_NODE(&s->s_instances);
INIT_HLIST_BL_HEAD(&s->s_anon);
+ mutex_init(&s->s_sync_lock);
INIT_LIST_HEAD(&s->s_inodes);
+ spin_lock_init(&s->s_inode_list_lock);
if (list_lru_init_memcg(&s->s_dentry_lru))
goto fail;
sync_filesystem(sb);
sb->s_flags &= ~MS_ACTIVE;
- fsnotify_unmount_inodes(&sb->s_inodes);
+ fsnotify_unmount_inodes(sb);
+ cgroup_writeback_umount();
evict_inodes(sb);
else if (error)
return -EAGAIN;
- if (dev == (1 << MINORBITS)) {
+ if (dev >= (1 << MINORBITS)) {
spin_lock(&unnamed_dev_lock);
ida_remove(&unnamed_dev_ida, dev);
if (unnamed_dev_start > dev)
*/
void __sb_end_write(struct super_block *sb, int level)
{
- percpu_counter_dec(&sb->s_writers.counter[level-1]);
- /*
- * Make sure s_writers are updated before we wake up waiters in
- * freeze_super().
- */
- smp_mb();
- if (waitqueue_active(&sb->s_writers.wait))
- wake_up(&sb->s_writers.wait);
- rwsem_release(&sb->s_writers.lock_map[level-1], 1, _RET_IP_);
+ percpu_up_read(sb->s_writers.rw_sem + level-1);
}
EXPORT_SYMBOL(__sb_end_write);
-#ifdef CONFIG_LOCKDEP
-/*
- * We want lockdep to tell us about possible deadlocks with freezing but
- * it's it bit tricky to properly instrument it. Getting a freeze protection
- * works as getting a read lock but there are subtle problems. XFS for example
- * gets freeze protection on internal level twice in some cases, which is OK
- * only because we already hold a freeze protection also on higher level. Due
- * to these cases we have to tell lockdep we are doing trylock when we
- * already hold a freeze protection for a higher freeze level.
- */
-static void acquire_freeze_lock(struct super_block *sb, int level, bool trylock,
- unsigned long ip)
-{
- int i;
-
- if (!trylock) {
- for (i = 0; i < level - 1; i++)
- if (lock_is_held(&sb->s_writers.lock_map[i])) {
- trylock = true;
- break;
- }
- }
- rwsem_acquire_read(&sb->s_writers.lock_map[level-1], 0, trylock, ip);
-}
-#endif
-
/*
* This is an internal function, please use sb_start_{write,pagefault,intwrite}
* instead.
*/
int __sb_start_write(struct super_block *sb, int level, bool wait)
{
-retry:
- if (unlikely(sb->s_writers.frozen >= level)) {
- if (!wait)
- return 0;
- wait_event(sb->s_writers.wait_unfrozen,
- sb->s_writers.frozen < level);
- }
+ bool force_trylock = false;
+ int ret = 1;
#ifdef CONFIG_LOCKDEP
- acquire_freeze_lock(sb, level, !wait, _RET_IP_);
-#endif
- percpu_counter_inc(&sb->s_writers.counter[level-1]);
/*
- * Make sure counter is updated before we check for frozen.
- * freeze_super() first sets frozen and then checks the counter.
+ * We want lockdep to tell us about possible deadlocks with freezing
+ * but it's it bit tricky to properly instrument it. Getting a freeze
+ * protection works as getting a read lock but there are subtle
+ * problems. XFS for example gets freeze protection on internal level
+ * twice in some cases, which is OK only because we already hold a
+ * freeze protection also on higher level. Due to these cases we have
+ * to use wait == F (trylock mode) which must not fail.
*/
- smp_mb();
- if (unlikely(sb->s_writers.frozen >= level)) {
- __sb_end_write(sb, level);
- goto retry;
+ if (wait) {
+ int i;
+
+ for (i = 0; i < level - 1; i++)
+ if (percpu_rwsem_is_held(sb->s_writers.rw_sem + i)) {
+ force_trylock = true;
+ break;
+ }
}
- return 1;
+#endif
+ if (wait && !force_trylock)
+ percpu_down_read(sb->s_writers.rw_sem + level-1);
+ else
+ ret = percpu_down_read_trylock(sb->s_writers.rw_sem + level-1);
+
+ WARN_ON(force_trylock & !ret);
+ return ret;
}
EXPORT_SYMBOL(__sb_start_write);
* @level: type of writers we wait for (normal vs page fault)
*
* This function waits until there are no writers of given type to given file
- * system. Caller of this function should make sure there can be no new writers
- * of type @level before calling this function. Otherwise this function can
- * livelock.
+ * system.
*/
static void sb_wait_write(struct super_block *sb, int level)
{
- s64 writers;
-
+ percpu_down_write(sb->s_writers.rw_sem + level-1);
/*
- * We just cycle-through lockdep here so that it does not complain
- * about returning with lock to userspace
+ * We are going to return to userspace and forget about this lock, the
+ * ownership goes to the caller of thaw_super() which does unlock.
+ *
+ * FIXME: we should do this before return from freeze_super() after we
+ * called sync_filesystem(sb) and s_op->freeze_fs(sb), and thaw_super()
+ * should re-acquire these locks before s_op->unfreeze_fs(sb). However
+ * this leads to lockdep false-positives, so currently we do the early
+ * release right after acquire.
*/
- rwsem_acquire(&sb->s_writers.lock_map[level-1], 0, 0, _THIS_IP_);
- rwsem_release(&sb->s_writers.lock_map[level-1], 1, _THIS_IP_);
-
- do {
- DEFINE_WAIT(wait);
+ percpu_rwsem_release(sb->s_writers.rw_sem + level-1, 0, _THIS_IP_);
+}
- /*
- * We use a barrier in prepare_to_wait() to separate setting
- * of frozen and checking of the counter
- */
- prepare_to_wait(&sb->s_writers.wait, &wait,
- TASK_UNINTERRUPTIBLE);
+static void sb_freeze_unlock(struct super_block *sb)
+{
+ int level;
- writers = percpu_counter_sum(&sb->s_writers.counter[level-1]);
- if (writers)
- schedule();
+ for (level = 0; level < SB_FREEZE_LEVELS; ++level)
+ percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_);
- finish_wait(&sb->s_writers.wait, &wait);
- } while (writers);
+ for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--)
+ percpu_up_write(sb->s_writers.rw_sem + level);
}
/**
return 0;
}
- /* From now on, no new normal writers can start */
sb->s_writers.frozen = SB_FREEZE_WRITE;
- smp_wmb();
-
/* Release s_umount to preserve sb_start_write -> s_umount ordering */
up_write(&sb->s_umount);
-
sb_wait_write(sb, SB_FREEZE_WRITE);
+ down_write(&sb->s_umount);
/* Now we go and block page faults... */
- down_write(&sb->s_umount);
sb->s_writers.frozen = SB_FREEZE_PAGEFAULT;
- smp_wmb();
-
sb_wait_write(sb, SB_FREEZE_PAGEFAULT);
/* All writers are done so after syncing there won't be dirty data */
/* Now wait for internal filesystem counter */
sb->s_writers.frozen = SB_FREEZE_FS;
- smp_wmb();
sb_wait_write(sb, SB_FREEZE_FS);
if (sb->s_op->freeze_fs) {
printk(KERN_ERR
"VFS:Filesystem freeze failed\n");
sb->s_writers.frozen = SB_UNFROZEN;
- smp_wmb();
+ sb_freeze_unlock(sb);
wake_up(&sb->s_writers.wait_unfrozen);
deactivate_locked_super(sb);
return ret;
return -EINVAL;
}
- if (sb->s_flags & MS_RDONLY)
+ if (sb->s_flags & MS_RDONLY) {
+ sb->s_writers.frozen = SB_UNFROZEN;
goto out;
+ }
if (sb->s_op->unfreeze_fs) {
error = sb->s_op->unfreeze_fs(sb);
}
}
-out:
sb->s_writers.frozen = SB_UNFROZEN;
- smp_wmb();
+ sb_freeze_unlock(sb);
+out:
wake_up(&sb->s_writers.wait_unfrozen);
deactivate_locked_super(sb);
-
return 0;
}
EXPORT_SYMBOL(thaw_super);
Code Review / kvmfornfv.git / blobdiff