[PATCH 05/10] btrfs: push struct writeback_control into start_delalloc_inodes

[Christoph Hellwig <hch@lst.de>]

In preparation for changing the filemap_fdatawrite_wbc API to not expose
the writeback_control to the callers, push the wbc declaration next to
the filemap_fdatawrite_wbc call and just pass thr nr_to_write value to
start_delalloc_inodes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/btrfs/inode.c | 51 ++++++++++++++++++++----------------------------
 1 file changed, 21 insertions(+), 30 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 9edb78fc57fc..b97d6c1f7772 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8709,15 +8709,13 @@ static struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode
  * some fairly slow code that needs optimization. This walks the list
  * of all the inodes with pending delalloc and forces them to disk.
  */
-static int start_delalloc_inodes(struct btrfs_root *root,
-				 struct writeback_control *wbc, bool snapshot,
-				 bool in_reclaim_context)
+static int start_delalloc_inodes(struct btrfs_root *root, long *nr_to_write,
+				 bool snapshot, bool in_reclaim_context)
 {
 	struct btrfs_delalloc_work *work, *next;
 	LIST_HEAD(works);
 	LIST_HEAD(splice);
 	int ret = 0;
-	bool full_flush = wbc->nr_to_write == LONG_MAX;
 
 	mutex_lock(&root->delalloc_mutex);
 	spin_lock(&root->delalloc_lock);
@@ -8743,7 +8741,7 @@ static int start_delalloc_inodes(struct btrfs_root *root,
 
 		if (snapshot)
 			set_bit(BTRFS_INODE_SNAPSHOT_FLUSH, &inode->runtime_flags);
-		if (full_flush) {
+		if (nr_to_write == NULL) {
 			work = btrfs_alloc_delalloc_work(tmp_inode);
 			if (!work) {
 				iput(tmp_inode);
@@ -8754,9 +8752,20 @@ static int start_delalloc_inodes(struct btrfs_root *root,
 			btrfs_queue_work(root->fs_info->flush_workers,
 					 &work->work);
 		} else {
-			ret = filemap_fdatawrite_wbc(tmp_inode->i_mapping, wbc);
+			struct writeback_control wbc = {
+				.nr_to_write = *nr_to_write,
+				.sync_mode = WB_SYNC_NONE,
+				.range_start = 0,
+				.range_end = LLONG_MAX,
+			};
+
+			ret = filemap_fdatawrite_wbc(tmp_inode->i_mapping,
+					&wbc);
 			btrfs_add_delayed_iput(inode);
-			if (ret || wbc->nr_to_write <= 0)
+
+			if (*nr_to_write != LONG_MAX)
+				*nr_to_write = wbc.nr_to_write;
+			if (ret || *nr_to_write <= 0)
 				goto out;
 		}
 		cond_resched();
@@ -8782,29 +8791,17 @@ static int start_delalloc_inodes(struct btrfs_root *root,
 
 int btrfs_start_delalloc_snapshot(struct btrfs_root *root, bool in_reclaim_context)
 {
-	struct writeback_control wbc = {
-		.nr_to_write = LONG_MAX,
-		.sync_mode = WB_SYNC_NONE,
-		.range_start = 0,
-		.range_end = LLONG_MAX,
-	};
 	struct btrfs_fs_info *fs_info = root->fs_info;
 
 	if (BTRFS_FS_ERROR(fs_info))
 		return -EROFS;
-
-	return start_delalloc_inodes(root, &wbc, true, in_reclaim_context);
+	return start_delalloc_inodes(root, NULL, true, in_reclaim_context);
 }
 
 int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, long nr,
 			       bool in_reclaim_context)
 {
-	struct writeback_control wbc = {
-		.nr_to_write = nr,
-		.sync_mode = WB_SYNC_NONE,
-		.range_start = 0,
-		.range_end = LLONG_MAX,
-	};
+	long *nr_to_write = nr == LONG_MAX ? NULL : &nr;
 	struct btrfs_root *root;
 	LIST_HEAD(splice);
 	int ret;
@@ -8816,13 +8813,6 @@ int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, long nr,
 	spin_lock(&fs_info->delalloc_root_lock);
 	list_splice_init(&fs_info->delalloc_roots, &splice);
 	while (!list_empty(&splice)) {
-		/*
-		 * Reset nr_to_write here so we know that we're doing a full
-		 * flush.
-		 */
-		if (nr == LONG_MAX)
-			wbc.nr_to_write = LONG_MAX;
-
 		root = list_first_entry(&splice, struct btrfs_root,
 					delalloc_root);
 		root = btrfs_grab_root(root);
@@ -8831,9 +8821,10 @@ int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, long nr,
 			       &fs_info->delalloc_roots);
 		spin_unlock(&fs_info->delalloc_root_lock);
 
-		ret = start_delalloc_inodes(root, &wbc, false, in_reclaim_context);
+		ret = start_delalloc_inodes(root, nr_to_write, false,
+				in_reclaim_context);
 		btrfs_put_root(root);
-		if (ret < 0 || wbc.nr_to_write <= 0)
+		if (ret < 0 || nr <= 0)
 			goto out;
 		spin_lock(&fs_info->delalloc_root_lock);
 	}
-- 
2.47.3