From 66cf3a8273abcac9c52b088f87f926e1a699d959 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 18 Jan 2023 16:35:13 -0500 Subject: [PATCH] btrfs: limit device extents to the device size commit 3c538de0f2a74d50aff7278c092f88ae59cee688 upstream. There was a recent regression in btrfs/177 that started happening with the size class patches ("btrfs: introduce size class to block group allocator"). This however isn't a regression introduced by those patches, but rather the bug was uncovered by a change in behavior in these patches. The patches triggered more chunk allocations in the ^free-space-tree case, which uncovered a race with device shrink. The problem is we will set the device total size to the new size, and use this to find a hole for a device extent. However during shrink we may have device extents allocated past this range, so we could potentially find a hole in a range past our new shrink size. We don't actually limit our found extent to the device size anywhere, we assume that we will not find a hole past our device size. This isn't true with shrink as we're relocating block groups and thus creating holes past the device size. Fix this by making sure we do not search past the new device size, and if we wander into any device extents that start after our device size simply break from the loop and use whatever hole we've already found. CC: stable@vger.kernel.org # 4.14+ Signed-off-by: Josef Bacik Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/volumes.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 65e4e88..f66bf1a 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1612,7 +1612,7 @@ again: if (ret < 0) goto out; - while (1) { + while (search_start < search_end) { l = path->nodes[0]; slot = path->slots[0]; if (slot >= btrfs_header_nritems(l)) { @@ -1635,6 +1635,9 @@ again: if (key.type != BTRFS_DEV_EXTENT_KEY) goto next; + if (key.offset > search_end) + break; + if (key.offset > search_start) { hole_size = key.offset - search_start; dev_extent_hole_check(device, &search_start, &hole_size, @@ -1695,6 +1698,7 @@ next: else ret = 0; + ASSERT(max_hole_start + max_hole_size <= search_end); out: btrfs_free_path(path); *start = max_hole_start; -- 2.7.4