| From a05dadfa77223e34ebe50593a68c15eede90b091 Mon Sep 17 00:00:00 2001 |
| From: Qu Wenruo <wqu@suse.com> |
| Date: Wed, 20 May 2020 14:58:51 +0800 |
| Subject: [PATCH] btrfs: reloc: clear DEAD_RELOC_TREE bit for orphan roots to |
| prevent runaway balance |
| |
| commit 1dae7e0e58b484eaa43d530f211098fdeeb0f404 upstream. |
| |
| [BUG] |
| There are several reported runaway balance, that balance is flooding the |
| log with "found X extents" where the X never changes. |
| |
| [CAUSE] |
| Commit d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after |
| merge_reloc_roots") introduced BTRFS_ROOT_DEAD_RELOC_TREE bit to |
| indicate that one subvolume has finished its tree blocks swap with its |
| reloc tree. |
| |
| However if balance is canceled or hits ENOSPC halfway, we didn't clear |
| the BTRFS_ROOT_DEAD_RELOC_TREE bit, leaving that bit hanging forever |
| until unmount. |
| |
| Any subvolume root with that bit, would cause backref cache to skip this |
| tree block, as it has finished its tree block swap. This would cause |
| all tree blocks of that root be ignored by balance, leading to runaway |
| balance. |
| |
| [FIX] |
| Fix the problem by also clearing the BTRFS_ROOT_DEAD_RELOC_TREE bit for |
| the original subvolume of orphan reloc root. |
| |
| Add an umount check for the stale bit still set. |
| |
| Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") |
| Signed-off-by: Qu Wenruo <wqu@suse.com> |
| Signed-off-by: David Sterba <dsterba@suse.com> |
| [Manually solve the conflicts due to no btrfs root refs rework] |
| Signed-off-by: David Sterba <dsterba@suse.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| [PG: use v5.4.x-stable version as per above rework.] |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c |
| index 958e6ddd1943..4147b569c64c 100644 |
| --- a/fs/btrfs/relocation.c |
| +++ b/fs/btrfs/relocation.c |
| @@ -2497,6 +2497,8 @@ void merge_reloc_roots(struct reloc_control *rc) |
| if (!IS_ERR(root)) { |
| if (root->reloc_root == reloc_root) |
| root->reloc_root = NULL; |
| + clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, |
| + &root->state); |
| } |
| |
| list_del_init(&reloc_root->root_list); |
| -- |
| 2.27.0 |
| |