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74e9795812
Create subvolume, create snapshot and delete subvolume all use
btrfs_subvolume_reserve_metadata() to reserve metadata for the changes
done to the parent subvolume's fs tree, which cannot be mediated in the
normal way via start_transaction. When quota groups (squota or qgroups)
are enabled, this reserves qgroup metadata of type PREALLOC. Once the
operation is associated to a transaction, we convert PREALLOC to
PERTRANS, which gets cleared in bulk at the end of the transaction.
However, the error paths of these three operations were not implementing
this lifecycle correctly. They unconditionally converted the PREALLOC to
PERTRANS in a generic cleanup step regardless of errors or whether the
operation was fully associated to a transaction or not. This resulted in
error paths occasionally converting this rsv to PERTRANS without calling
record_root_in_trans successfully, which meant that unless that root got
recorded in the transaction by some other thread, the end of the
transaction would not free that root's PERTRANS, leaking it. Ultimately,
this resulted in hitting a WARN in CONFIG_BTRFS_DEBUG builds at unmount
for the leaked reservation.
The fix is to ensure that every qgroup PREALLOC reservation observes the
following properties:
1. any failure before record_root_in_trans is called successfully
results in freeing the PREALLOC reservation.
2. after record_root_in_trans, we convert to PERTRANS, and now the
transaction owns freeing the reservation.
This patch enforces those properties on the three operations. Without
it, generic/269 with squotas enabled at mkfs time would fail in ~5-10
runs on my system. With this patch, it ran successfully 1000 times in a
row.
Fixes: e85fde5162 ("btrfs: qgroup: fix qgroup meta rsv leak for subvolume operations")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
43 lines
1.6 KiB
C
43 lines
1.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef BTRFS_ROOT_TREE_H
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#define BTRFS_ROOT_TREE_H
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#include <linux/types.h>
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struct fscrypt_str;
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struct extent_buffer;
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struct btrfs_key;
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struct btrfs_root;
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struct btrfs_root_item;
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struct btrfs_path;
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struct btrfs_fs_info;
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struct btrfs_block_rsv;
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struct btrfs_trans_handle;
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int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
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struct btrfs_block_rsv *rsv,
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int nitems, bool use_global_rsv);
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int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
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u64 ref_id, u64 dirid, u64 sequence,
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const struct fscrypt_str *name);
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int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
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u64 ref_id, u64 dirid, u64 *sequence,
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const struct fscrypt_str *name);
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int btrfs_del_root(struct btrfs_trans_handle *trans, const struct btrfs_key *key);
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int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
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const struct btrfs_key *key,
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struct btrfs_root_item *item);
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int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
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struct btrfs_key *key, struct btrfs_root_item *item);
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int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
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struct btrfs_path *path, struct btrfs_root_item *root_item,
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struct btrfs_key *root_key);
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int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info);
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void btrfs_set_root_node(struct btrfs_root_item *item,
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struct extent_buffer *node);
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void btrfs_check_and_init_root_item(struct btrfs_root_item *item);
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void btrfs_update_root_times(struct btrfs_trans_handle *trans, struct btrfs_root *root);
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#endif
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