[PATCH 35/50] fs: remove I_WILL_FREE|I_FREEING from fs-writeback.c

[Josef Bacik <josef@toxicpanda.com>]

Now that we have the reference count to indicate live inodes, we can
remove all of the uses of I_WILL_FREE and I_FREEING in fs-writeback.c
and use the appropriate reference count checks.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/fs-writeback.c | 47 ++++++++++++++++++++++++++---------------------
 1 file changed, 26 insertions(+), 21 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 789c4228412c..0ea6d0e86791 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -129,7 +129,7 @@ static bool inode_io_list_move_locked(struct inode *inode,
 {
 	assert_spin_locked(&wb->list_lock);
 	assert_spin_locked(&inode->i_lock);
-	WARN_ON_ONCE(inode->i_state & I_FREEING);
+	WARN_ON_ONCE(!refcount_read(&inode->i_count));
 
 	if (list_empty(&inode->i_io_list))
 		iobj_get(inode);
@@ -314,7 +314,7 @@ static void inode_cgwb_move_to_attached(struct inode *inode,
 {
 	assert_spin_locked(&wb->list_lock);
 	assert_spin_locked(&inode->i_lock);
-	WARN_ON_ONCE(inode->i_state & I_FREEING);
+	WARN_ON_ONCE(!refcount_read(&inode->i_count));
 
 	inode->i_state &= ~I_SYNC_QUEUED;
 	if (wb != &wb->bdi->wb)
@@ -415,10 +415,10 @@ static bool inode_do_switch_wbs(struct inode *inode,
 	xa_lock_irq(&mapping->i_pages);
 
 	/*
-	 * Once I_FREEING or I_WILL_FREE are visible under i_lock, the eviction
-	 * path owns the inode and we shouldn't modify ->i_io_list.
+	 * Once the refcount is 0, the eviction path owns the inode and we
+	 * shouldn't modify ->i_io_list.
 	 */
-	if (unlikely(inode->i_state & (I_FREEING | I_WILL_FREE)))
+	if (unlikely(!refcount_read(&inode->i_count)))
 		goto skip_switch;
 
 	trace_inode_switch_wbs(inode, old_wb, new_wb);
@@ -570,13 +570,16 @@ static bool inode_prepare_wbs_switch(struct inode *inode,
 	/* while holding I_WB_SWITCH, no one else can update the association */
 	spin_lock(&inode->i_lock);
 	if (!(inode->i_sb->s_flags & SB_ACTIVE) ||
-	    inode->i_state & (I_WB_SWITCH | I_FREEING | I_WILL_FREE) ||
+	    inode->i_state & I_WB_SWITCH ||
 	    inode_to_wb(inode) == new_wb) {
 		spin_unlock(&inode->i_lock);
 		return false;
 	}
+	if (!inode_tryget(inode)) {
+		spin_unlock(&inode->i_lock);
+		return false;
+	}
 	inode->i_state |= I_WB_SWITCH;
-	__iget(inode);
 	spin_unlock(&inode->i_lock);
 
 	return true;
@@ -1207,7 +1210,7 @@ static void inode_cgwb_move_to_attached(struct inode *inode,
 {
 	assert_spin_locked(&wb->list_lock);
 	assert_spin_locked(&inode->i_lock);
-	WARN_ON_ONCE(inode->i_state & I_FREEING);
+	WARN_ON_ONCE(!refcount_read(&inode->i_count));
 
 	inode->i_state &= ~I_SYNC_QUEUED;
 	inode_delete_from_io_list(inode);
@@ -1405,7 +1408,7 @@ static void redirty_tail_locked(struct inode *inode, struct bdi_writeback *wb)
 	 * tracking. Flush worker will ignore this inode anyway and it will
 	 * trigger assertions in inode_io_list_move_locked().
 	 */
-	if (inode->i_state & I_FREEING) {
+	if (!refcount_read(&inode->i_count)) {
 		inode_delete_from_io_list(inode);
 		wb_io_lists_depopulated(wb);
 		return;
@@ -1621,7 +1624,7 @@ static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
 			  struct writeback_control *wbc,
 			  unsigned long dirtied_before)
 {
-	if (inode->i_state & I_FREEING)
+	if (!refcount_read(&inode->i_count))
 		return;
 
 	/*
@@ -1787,7 +1790,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
  * whether it is a data-integrity sync (%WB_SYNC_ALL) or not (%WB_SYNC_NONE).
  *
  * To prevent the inode from going away, either the caller must have a reference
- * to the inode, or the inode must have I_WILL_FREE or I_FREEING set.
+ * to the inode, or the inode must have a zero refcount.
  */
 static int writeback_single_inode(struct inode *inode,
 				  struct writeback_control *wbc)
@@ -1797,9 +1800,7 @@ static int writeback_single_inode(struct inode *inode,
 
 	spin_lock(&inode->i_lock);
 	if (!refcount_read(&inode->i_count))
-		WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING)));
-	else
-		WARN_ON(inode->i_state & I_WILL_FREE);
+		WARN_ON(inode->i_state & I_NEW);
 
 	if (inode->i_state & I_SYNC) {
 		/*
@@ -1837,7 +1838,7 @@ static int writeback_single_inode(struct inode *inode,
 	 * If the inode is freeing, its i_io_list shoudn't be updated
 	 * as it can be finally deleted at this moment.
 	 */
-	if (!(inode->i_state & I_FREEING)) {
+	if (refcount_read(&inode->i_count)) {
 		/*
 		 * If the inode is now fully clean, then it can be safely
 		 * removed from its writeback list (if any). Otherwise the
@@ -1957,7 +1958,7 @@ static long writeback_sb_inodes(struct super_block *sb,
 		 * kind writeout is handled by the freer.
 		 */
 		spin_lock(&inode->i_lock);
-		if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
+		if ((inode->i_state & I_NEW) || !refcount_read(&inode->i_count)) {
 			redirty_tail_locked(inode, wb);
 			spin_unlock(&inode->i_lock);
 			continue;
@@ -2615,7 +2616,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 			if (inode_unhashed(inode))
 				goto out_unlock;
 		}
-		if (inode->i_state & I_FREEING)
+		if (!refcount_read(&inode->i_count))
 			goto out_unlock;
 
 		/*
@@ -2729,13 +2730,17 @@ static void wait_sb_inodes(struct super_block *sb)
 		spin_unlock_irq(&sb->s_inode_wblist_lock);
 
 		spin_lock(&inode->i_lock);
-		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
+		if (inode->i_state & I_NEW) {
+			spin_unlock(&inode->i_lock);
+			spin_lock_irq(&sb->s_inode_wblist_lock);
+			continue;
+		}
+
+		if (!inode_tryget(inode)) {
 			spin_unlock(&inode->i_lock);
-
 			spin_lock_irq(&sb->s_inode_wblist_lock);
 			continue;
 		}
-		__iget(inode);
 
 		/*
 		 * We could have potentially ended up on the cached LRU list, so
@@ -2886,7 +2891,7 @@ EXPORT_SYMBOL(sync_inodes_sb);
  * This function commits an inode to disk immediately if it is dirty. This is
  * primarily needed by knfsd.
  *
- * The caller must either have a ref on the inode or must have set I_WILL_FREE.
+ * The caller must either have a ref on the inode or the inode must have a zero refcount.
  */
 int write_inode_now(struct inode *inode, int sync)
 {
-- 
2.49.0