On 2019/2/21 下午4:22, Qu Wenruo wrote: > There are a lot of error reports complaining about transid error in the > mail list. > > Under most case, the on-disk transid is lower than expected transid. > This may indicate that some tree blocks are not written back to disk > before writing super blocks. > > This patch will add a safe net for developers, by calling > btrfs_write_and_wait_transaction() before setting transaction unblocked > and double check btree_inode and dirty_pages io_tree, to ensure no tree > blocks are still dirty or under writeback. > > Signed-off-by: Qu Wenruo <w...@suse.com>
Please discard this patch.
As Nikolay suggested, the check doesn't make much sense.
>
> + /* Last safenet or developer to catch any unwritten tree blocks */
> + if (IS_ENABLED(CONFIG_BTRFS_DEBUG)) {
> + u64 found_start = 0;
> + u64 found_end = 0;
> +
> + ret = btrfs_write_and_wait_transaction(trans);
> + if (ret) {
> + btrfs_handle_fs_error(fs_info, ret,
> + "Error while writing out
> transaction");
> + mutex_unlock(&fs_info->tree_log_mutex);
> + goto scrub_continue;
> + }
> +
> + /* No dirty extent should exist in btree inode */
> + ret = test_range_bit(&trans->transaction->dirty_pages, 0,
> + (u64)-1, EXTENT_DIRTY | EXTENT_WRITEBACK,
> + 0, NULL);
For dirty_pages, btrfs_write_and_wait_transaction() will clear all bits.
So the check will always return 0.
> + if (ret > 0) {
> + WARN(1,
> + "dirty_pages not fully written back, start=%llu len=%llu\n",
> + found_start, found_end + 1 - found_start);
> + ret = -EUCLEAN;
> + mutex_unlock(&fs_info->tree_log_mutex);
> + goto scrub_continue;
> + }
> + ret = test_range_bit(&BTRFS_I(fs_info->btree_inode)->io_tree, 0,
> + (u64)-1, EXTENT_DIRTY | EXTENT_WRITEBACK,
> + 0, NULL);
btree_inode doesn't really carry EXTENT_DIRTY bit.
It only carries EXTENT_LOCK, and are mostly for tree read locking.
So this check doesn't make much sense either.
Thanks,
Qu
> + if (ret > 0) {
> + WARN(1,
> + "btree io_tree not fully written back, start=%llu len=%llu\n",
> + found_start, found_end + 1 - found_start);
> + ret = -EUCLEAN;
> + mutex_unlock(&fs_info->tree_log_mutex);
> + goto scrub_continue;
> + }
> + }
> +
> spin_lock(&fs_info->trans_lock);
> cur_trans->state = TRANS_STATE_UNBLOCKED;
> fs_info->running_transaction = NULL;
>
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