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btrfs: remove BUG() after failure to insert delayed dir index item

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Instead of calling BUG() when we fail to insert a delayed dir index item
into the delayed node's tree, we can just release all the resources we
have allocated/acquired before and return the error to the caller. This is
fine because all existing call chains undo anything they have done before
calling btrfs_insert_delayed_dir_index() or BUG_ON (when creating pending
snapshots in the transaction commit path).

So remove the BUG() call and do proper error handling.

This relates to a syzbot report linked below, but does not fix it because
it only prevents hitting a BUG(), it does not fix the issue where somehow
we attempt to use twice the same index number for different index items.

Link: https://lore.kernel.org/linux-btrfs/00000000000036e1290603e097e0@google.com/
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana 2023-08-28 09:06:43 +01:00 committed by David Sterba
parent 91bfe3104b
commit 2c58c3931e
1 changed files with 47 additions and 27 deletions
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74
fs/btrfs/delayed-inode.c
View File

@ -1426,7 +1426,29 @@ void btrfs_balance_delayed_items(struct btrfs_fs_info *fs_info)
btrfs_wq_run_delayed_node(delayed_root, fs_info, BTRFS_DELAYED_BATCH);
}
/* Will return 0 or -ENOMEM */
static void btrfs_release_dir_index_item_space(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
const u64 bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
return;
/*
* Adding the new dir index item does not require touching another
* leaf, so we can release 1 unit of metadata that was previously
* reserved when starting the transaction. This applies only to
* the case where we had a transaction start and excludes the
* transaction join case (when replaying log trees).
*/
trace_btrfs_space_reservation(fs_info, "transaction",
trans->transid, bytes, 0);
btrfs_block_rsv_release(fs_info, trans->block_rsv, bytes, NULL);
ASSERT(trans->bytes_reserved >= bytes);
trans->bytes_reserved -= bytes;
}
/* Will return 0, -ENOMEM or -EEXIST (index number collision, unexpected). */
int btrfs_insert_delayed_dir_index(struct btrfs_trans_handle *trans,
const char *name, int name_len,
struct btrfs_inode *dir,
@ -1468,6 +1490,27 @@ int btrfs_insert_delayed_dir_index(struct btrfs_trans_handle *trans,
mutex_lock(&delayed_node->mutex);
/*
* First attempt to insert the delayed item. This is to make the error
* handling path simpler in case we fail (-EEXIST). There's no risk of
* any other task coming in and running the delayed item before we do
* the metadata space reservation below, because we are holding the
* delayed node's mutex and that mutex must also be locked before the
* node's delayed items can be run.
*/
ret = __btrfs_add_delayed_item(delayed_node, delayed_item);
if (unlikely(ret)) {
btrfs_err(trans->fs_info,
"error adding delayed dir index item, name: %.*s, index: %llu, root: %llu, dir: %llu, dir->index_cnt: %llu, delayed_node->index_cnt: %llu, error: %d",
name_len, name, index, btrfs_root_id(delayed_node->root),
delayed_node->inode_id, dir->index_cnt,
delayed_node->index_cnt, ret);
btrfs_release_delayed_item(delayed_item);
btrfs_release_dir_index_item_space(trans);
mutex_unlock(&delayed_node->mutex);
goto release_node;
}
if (delayed_node->index_item_leaves == 0 ||
delayed_node->curr_index_batch_size + data_len > leaf_data_size) {
delayed_node->curr_index_batch_size = data_len;
@ -1485,37 +1528,14 @@ int btrfs_insert_delayed_dir_index(struct btrfs_trans_handle *trans,
* impossible.
*/
if (WARN_ON(ret)) {
mutex_unlock(&delayed_node->mutex);
btrfs_release_delayed_item(delayed_item);
mutex_unlock(&delayed_node->mutex);
goto release_node;
}
delayed_node->index_item_leaves++;
} else if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags)) {
const u64 bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
/*
* Adding the new dir index item does not require touching another
* leaf, so we can release 1 unit of metadata that was previously
* reserved when starting the transaction. This applies only to
* the case where we had a transaction start and excludes the
* transaction join case (when replaying log trees).
*/
trace_btrfs_space_reservation(fs_info, "transaction",
trans->transid, bytes, 0);
btrfs_block_rsv_release(fs_info, trans->block_rsv, bytes, NULL);
ASSERT(trans->bytes_reserved >= bytes);
trans->bytes_reserved -= bytes;
}
ret = __btrfs_add_delayed_item(delayed_node, delayed_item);
if (unlikely(ret)) {
btrfs_err(trans->fs_info,
"error adding delayed dir index item, name: %.*s, index: %llu, root: %llu, dir: %llu, dir->index_cnt: %llu, delayed_node->index_cnt: %llu, error: %d",
name_len, name, index, btrfs_root_id(delayed_node->root),
delayed_node->inode_id, dir->index_cnt,
delayed_node->index_cnt, ret);
BUG();
} else {
btrfs_release_dir_index_item_space(trans);
}
mutex_unlock(&delayed_node->mutex);