Patch "btrfs: Fix no_space in write and rm loop" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

btrfs: Fix no_space in write and rm loop

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
btrfs-fix-no_space-in-write-and-rm-loop.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Zhao Lei <[email protected]>
Date: Tue, 1 Dec 2015 18:39:40 +0800
Subject: btrfs: Fix no_space in write and rm loop

From: Zhao Lei <[email protected]>

commit e1746e8381cd2af421f75557b5cae3604fc18b35 upstream.

I see no_space in v4.4-rc1 again in xfstests generic/102. It happened randomly in some node only.
(one of 4 phy-node, and a kvm with non-virtio block driver)

By bisect, we can found the first-bad is:
commit bdced438acd8 ("block: setup bi_phys_segments after splitting")'
But above patch only triggered the bug by making bio operation faster(or slower).

Main reason is in our space_allocating code, we need to commit page writeback before wait it complish, this patch fixed above bug.

BTW, there is another reason for generic/102 fail, caused by disable default mixed-blockgroup, I'll fix it in xfstests.

---
 fs/btrfs/extent-tree.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

@@ -4086,8 +4086,10 @@ commit_trans:
 		    !atomic_read(&root->fs_info->open_ioctl_trans)) {
 			need_commit--;
 
-			if (need_commit > 0)
+			if (need_commit > 0) {
+				btrfs_start_delalloc_roots(fs_info, 0, -1);
 				btrfs_wait_ordered_roots(fs_info, -1);
+			}
 
 			trans = btrfs_join_transaction(root);
 			if (IS_ERR(trans))

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/btrfs-fix-no_space-in-write-and-rm-loop.patch