From 8b8b08cbfb9021af4b54b4175fc4c51d655aac8c Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Tue, 19 Jul 2016 05:52:36 -0700 Subject: [PATCH] Btrfs: fix delalloc accounting after copy_from_user faults Commit 56244ef151c3cd11 was almost but not quite enough to fix the reservation math after btrfs_copy_from_user returned partial copies. Some users are still seeing warnings in btrfs_destroy_inode, and with a long enough test run I'm able to trigger them as well. This patch fixes the accounting math again, bringing it much closer to the way it was before the sectorsize conversion Chandan did. The problem is accounting for the offset into the page/sector when we do a partial copy. This one just uses the dirty_sectors variable which should already be updated properly. Signed-off-by: Chris Mason cc: stable@vger.kernel.org # v4.6+ --- fs/btrfs/file.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index f3f61d1ad18a..bcfb4a27ddd4 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1629,13 +1629,11 @@ again: * managed to copy. */ if (num_sectors > dirty_sectors) { - /* - * we round down because we don't want to count - * any partial blocks actually sent through the - * IO machines - */ - release_bytes = round_down(release_bytes - copied, - root->sectorsize); + + /* release everything except the sectors we dirtied */ + release_bytes -= dirty_sectors << + root->fs_info->sb->s_blocksize_bits; + if (copied > 0) { spin_lock(&BTRFS_I(inode)->lock); BTRFS_I(inode)->outstanding_extents++; -- 2.20.1