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Subject[PATCH AUTOSEL 4.4 15/65] btrfs: don't create or leak aliased root while cleaning up orphans
Date
From: Jeff Mahoney <jeffm@suse.com>

[ Upstream commit 35bbb97fc898aeb874cb7c8b746f091caa359994 ]

commit 909c3a22da3 (Btrfs: fix loading of orphan roots leading to BUG_ON)
avoids the BUG_ON but can add an aliased root to the dead_roots list or
leak the root.

Since we've already been loading roots into the radix tree, we should
use it before looking the root up on disk.

Cc: <stable@vger.kernel.org> # 4.5
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/disk-io.c | 4 ++--
fs/btrfs/disk-io.h | 2 ++
fs/btrfs/root-tree.c | 27 ++++++++++++++++++---------
3 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a2001abbe379..120363d0f981 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1608,8 +1608,8 @@ int btrfs_init_fs_root(struct btrfs_root *root)
return ret;
}

-static struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
- u64 root_id)
+struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
+ u64 root_id)
{
struct btrfs_root *root;

diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index adeb31830b9c..3c9819403487 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -68,6 +68,8 @@ struct extent_buffer *btrfs_find_tree_block(struct btrfs_fs_info *fs_info,
struct btrfs_root *btrfs_read_fs_root(struct btrfs_root *tree_root,
struct btrfs_key *location);
int btrfs_init_fs_root(struct btrfs_root *root);
+struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
+ u64 root_id);
int btrfs_insert_fs_root(struct btrfs_fs_info *fs_info,
struct btrfs_root *root);
void btrfs_free_fs_roots(struct btrfs_fs_info *fs_info);
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 2c849b08a91b..6a6efb26d52f 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -272,6 +272,23 @@ int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
root_key.objectid = key.offset;
key.offset++;

+ /*
+ * The root might have been inserted already, as before we look
+ * for orphan roots, log replay might have happened, which
+ * triggers a transaction commit and qgroup accounting, which
+ * in turn reads and inserts fs roots while doing backref
+ * walking.
+ */
+ root = btrfs_lookup_fs_root(tree_root->fs_info,
+ root_key.objectid);
+ if (root) {
+ WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
+ &root->state));
+ if (btrfs_root_refs(&root->root_item) == 0)
+ btrfs_add_dead_root(root);
+ continue;
+ }
+
root = btrfs_read_fs_root(tree_root, &root_key);
err = PTR_ERR_OR_ZERO(root);
if (err && err != -ENOENT) {
@@ -310,16 +327,8 @@ int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);

err = btrfs_insert_fs_root(root->fs_info, root);
- /*
- * The root might have been inserted already, as before we look
- * for orphan roots, log replay might have happened, which
- * triggers a transaction commit and qgroup accounting, which
- * in turn reads and inserts fs roots while doing backref
- * walking.
- */
- if (err == -EEXIST)
- err = 0;
if (err) {
+ BUG_ON(err == -EEXIST);
btrfs_free_fs_root(root);
break;
}
--
2.17.1
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