#define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1)
/* one round can affect upto 5 slots */
+static atomic_t isw_nr_in_flight = ATOMIC_INIT(0);
+static struct workqueue_struct *isw_wq;
+
void __inode_attach_wb(struct inode *inode, struct page *page)
{
struct backing_dev_info *bdi = inode_to_bdi(inode);
wb_get(wb);
spin_unlock(&inode->i_lock);
spin_lock(&wb->list_lock);
- wb_put(wb); /* not gonna deref it anymore */
/* i_wb may have changed inbetween, can't use inode_to_wb() */
- if (likely(wb == inode->i_wb))
- return wb; /* @inode already has ref */
+ if (likely(wb == inode->i_wb)) {
+ wb_put(wb); /* @inode already has ref */
+ return wb;
+ }
spin_unlock(&wb->list_lock);
+ wb_put(wb);
cpu_relax();
spin_lock(&inode->i_lock);
}
iput(inode);
kfree(isw);
+
+ atomic_dec(&isw_nr_in_flight);
}
static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head)
/* needs to grab bh-unsafe locks, bounce to work item */
INIT_WORK(&isw->work, inode_switch_wbs_work_fn);
- schedule_work(&isw->work);
+ queue_work(isw_wq, &isw->work);
}
/**
/* while holding I_WB_SWITCH, no one else can update the association */
spin_lock(&inode->i_lock);
- if (inode->i_state & (I_WB_SWITCH | I_FREEING) ||
+ if (!(inode->i_sb->s_flags & MS_ACTIVE) ||
+ inode->i_state & (I_WB_SWITCH | I_FREEING) ||
inode_to_wb(inode) == isw->new_wb) {
spin_unlock(&inode->i_lock);
goto out_free;
ihold(inode);
isw->inode = inode;
+ atomic_inc(&isw_nr_in_flight);
+
/*
* In addition to synchronizing among switchers, I_WB_SWITCH tells
* the RCU protected stat update paths to grab the mapping's
wb_put(last_wb);
}
+/**
+ * cgroup_writeback_umount - flush inode wb switches for umount
+ *
+ * This function is called when a super_block is about to be destroyed and
+ * flushes in-flight inode wb switches. An inode wb switch goes through
+ * RCU and then workqueue, so the two need to be flushed in order to ensure
+ * that all previously scheduled switches are finished. As wb switches are
+ * rare occurrences and synchronize_rcu() can take a while, perform
+ * flushing iff wb switches are in flight.
+ */
+void cgroup_writeback_umount(void)
+{
+ if (atomic_read(&isw_nr_in_flight)) {
+ synchronize_rcu();
+ flush_workqueue(isw_wq);
+ }
+}
+
+static int __init cgroup_writeback_init(void)
+{
+ isw_wq = alloc_workqueue("inode_switch_wbs", 0, 0);
+ if (!isw_wq)
+ return -ENOMEM;
+ return 0;
+}
+fs_initcall(cgroup_writeback_init);
+
#else /* CONFIG_CGROUP_WRITEBACK */
static struct bdi_writeback *
* we go e.g. from filesystem. Flusher thread uses __writeback_single_inode()
* and does more profound writeback list handling in writeback_sb_inodes().
*/
-static int
-writeback_single_inode(struct inode *inode, struct bdi_writeback *wb,
- struct writeback_control *wbc)
+static int writeback_single_inode(struct inode *inode,
+ struct writeback_control *wbc)
{
+ struct bdi_writeback *wb;
int ret = 0;
spin_lock(&inode->i_lock);
ret = __writeback_single_inode(inode, wbc);
wbc_detach_inode(wbc);
- spin_lock(&wb->list_lock);
+
+ wb = inode_to_wb_and_lock_list(inode);
spin_lock(&inode->i_lock);
/*
* If inode is clean, remove it from writeback lists. Otherwise don't
while (!list_empty(&wb->b_io)) {
struct inode *inode = wb_inode(wb->b_io.prev);
+ struct bdi_writeback *tmp_wb;
if (inode->i_sb != sb) {
if (work->sb) {
cond_resched();
}
-
- spin_lock(&wb->list_lock);
+ /*
+ * Requeue @inode if still dirty. Be careful as @inode may
+ * have been switched to another wb in the meantime.
+ */
+ tmp_wb = inode_to_wb_and_lock_list(inode);
spin_lock(&inode->i_lock);
if (!(inode->i_state & I_DIRTY_ALL))
wrote++;
- requeue_inode(inode, wb, &wbc);
+ requeue_inode(inode, tmp_wb, &wbc);
inode_sync_complete(inode);
spin_unlock(&inode->i_lock);
+ if (unlikely(tmp_wb != wb)) {
+ spin_unlock(&tmp_wb->list_lock);
+ spin_lock(&wb->list_lock);
+ }
+
/*
* bail out to wb_writeback() often enough to check
* background threshold and other termination conditions.
(dirtytime && (inode->i_state & I_DIRTY_INODE)))
return;
- if (unlikely(block_dump))
+ if (unlikely(block_dump > 1))
block_dump___mark_inode_dirty(inode);
spin_lock(&inode->i_lock);
*/
int write_inode_now(struct inode *inode, int sync)
{
- struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
struct writeback_control wbc = {
.nr_to_write = LONG_MAX,
.sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE,
wbc.nr_to_write = 0;
might_sleep();
- return writeback_single_inode(inode, wb, &wbc);
+ return writeback_single_inode(inode, &wbc);
}
EXPORT_SYMBOL(write_inode_now);
*/
int sync_inode(struct inode *inode, struct writeback_control *wbc)
{
- return writeback_single_inode(inode, &inode_to_bdi(inode)->wb, wbc);
+ return writeback_single_inode(inode, wbc);
}
EXPORT_SYMBOL(sync_inode);
projects / firefly-linux-kernel-4.4.55.git / blobdiff