Btrfs: change how we update the global block rsv (fb4b10e5) · Commits · 戴 / test

I'm writing a tool to visualize the enospc system in order to help debug enospc bugs and I found weird data and ran it down to when we update the global block rsv. We add all of the remaining free space to the block rsv, do a trace event, then remove the extra and do another trace event. This makes my visualization look silly and is unintuitive code as well. Fix this stuff to only add the amount we are missing, or free the amount we are missing. This is less clean to read but more explicit in what it is doing, as well as only emitting events for values that make sense. Thanks, Signed-off-by:

Josef Bacik <jbacik@fb.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

+20 −14

Original line number	Diff line number	Diff line
		@@ -5373,27 +5373,33 @@ static void update_global_block_rsv(struct btrfs_fs_info *fs_info)

		block_rsv->size = min_t(u64, num_bytes, SZ_512M);

		if (block_rsv->reserved < block_rsv->size) {
		num_bytes = sinfo->bytes_used + sinfo->bytes_pinned +
		sinfo->bytes_reserved + sinfo->bytes_readonly +
		sinfo->bytes_may_use;

		if (sinfo->total_bytes > num_bytes) {
		num_bytes = sinfo->total_bytes - num_bytes;
		num_bytes = min(num_bytes,
		block_rsv->size - block_rsv->reserved);
		block_rsv->reserved += num_bytes;
		sinfo->bytes_may_use += num_bytes;
		trace_btrfs_space_reservation(fs_info, "space_info",
		sinfo->flags, num_bytes, 1);
		sinfo->flags, num_bytes,
		1);
		}

		if (block_rsv->reserved >= block_rsv->size) {
		} else if (block_rsv->reserved > block_rsv->size) {
		num_bytes = block_rsv->reserved - block_rsv->size;
		sinfo->bytes_may_use -= num_bytes;
		trace_btrfs_space_reservation(fs_info, "space_info",
		sinfo->flags, num_bytes, 0);
		block_rsv->reserved = block_rsv->size;
		block_rsv->full = 1;
		}

		if (block_rsv->reserved == block_rsv->size)
		block_rsv->full = 1;
		else
		block_rsv->full = 0;

		spin_unlock(&block_rsv->lock);
		spin_unlock(&sinfo->lock);
		}

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