Re: [PATCH 3/3] btrfs-progs: convert: report available space before convertion happens

[Su Yue <Damenly_Su@gmx.com>]

On Wed 29 Jul 2020 at 16:40, Qu Wenruo <wqu@suse.com> wrote:

> Now if an ENOSPC error happened, the free space report would
> help user to determine if it's a real ENOSPC or a bug in btrfs.
>
> The reported free space is the calculated free space, which
> doesn't include super block space, nor merged data chunks.
>
> The free space is always smaller than the reported available
> space of the original fs, as we need extra padding space for
> used space to avoid too fragmented data chunks.
>
> The output exact would be:
>
> $ ./btrfs-convert  /dev/nvme/btrfs create btrfs filesystem:
>         blocksize: 4096 nodesize:  16384 features:  extref,
>         skinny-metadata (default) checksum:  crc32c
> free space report: free / total = 0 / 10737418240 (0%) <<<
> ERROR: unable to create initial ctree: No space left on device
> WARNING: an error occurred during conversion, the original
> filesystem is not modified
>
> Signed-off-by: Qu Wenruo <wqu@suse.com> ---
>  convert/common.h    |  9 +++++++++ convert/main.c      | 26
>  ++++++++++++++++++++++++-- convert/source-fs.c |  1 + 3 files
>  changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/convert/common.h b/convert/common.h index
> 7ec26cd996d3..2c7799433294 100644 --- a/convert/common.h +++
> b/convert/common.h @@ -35,6 +35,7 @@ struct
> btrfs_convert_context {
>  	u64 inodes_count; u64 free_inodes_count; u64 total_bytes;
> +	u64 free_bytes_initial;
>  	char *volume_name; const struct btrfs_convert_operations
>  *convert_ops;
> @@ -47,6 +48,14 @@ struct btrfs_convert_context {
>  	/* Free space which is not covered by data_chunks */ struct
>  cache_tree free_space;
> +	/* +	 * Free space reserved for ENOSPC report, it's just a
> copy +	 * free_space.  +	 * But after initial calculation,
> free_space_initial is no longer +	 * updated, so we have a good
> idea on how many free space we really +	 * have for btrfs.  +
> */ +	struct cache_tree free_space_initial;
>  	void *fs_data; };
> diff --git a/convert/main.c b/convert/main.c index
> 451e4f158689..49c95e092cbb 100644 --- a/convert/main.c +++
> b/convert/main.c @@ -727,6 +727,23 @@ out:
>  	return ret; }
> +static int copy_free_space_tree(struct btrfs_convert_context
> *cctx) +{ +	struct cache_tree *src = &cctx->free_space; +
> struct cache_tree *dst = &cctx->free_space_initial; +	struct
> cache_extent *cache; +	int ret = 0; + +	for (cache =
> search_cache_extent(src, 0); cache; +	     cache =
> next_cache_extent(cache)) { +		ret =
> add_merge_cache_extent(dst, cache->start, cache->size); +		if
> (ret < 0) +			return ret; +
> cctx->free_bytes_initial += cache->size; +	} +	return ret; +}
> +
>  /*
>   * Read used space, and since we have the used space, *
>   calculate data_chunks and free for later mkfs
> @@ -740,7 +757,10 @@ static int convert_read_used_space(struct
> btrfs_convert_context *cctx)
>  		return ret;  ret = calculate_available_space(cctx);
> -	return ret; +	if (ret < 0) +		return ret; + +	return
> copy_free_space_tree(cctx);
>  }  /*
> @@ -1165,7 +1185,9 @@ static int do_convert(const char *devname,
> u32 convert_flags, u32 nodesize,
>  	printf("\tnodesize:  %u\n", nodesize); printf("\tfeatures:
>  %s\n", features_buf); printf("\tchecksum:  %s\n",
>  btrfs_super_csum_name(csum_type));
> - +	printf("free space report: free / total = %llu / %llu
> (%lld%%)\n", +		cctx.free_bytes_initial, cctx.total_bytes,
> +		cctx.free_bytes_initial * 100 / cctx.total_bytes);
>  	memset(&mkfs_cfg, 0, sizeof(mkfs_cfg)); mkfs_cfg.csum_type =
>  csum_type; mkfs_cfg.label = cctx.volume_name;
> diff --git a/convert/source-fs.c b/convert/source-fs.c index
> f7fd3d6055b7..d2f7a825238d 100644 --- a/convert/source-fs.c +++
> b/convert/source-fs.c @@ -74,6 +74,7 @@ void
> init_convert_context(struct btrfs_convert_context *cctx)
>  	cache_tree_init(&cctx->used_space);
>  cache_tree_init(&cctx->data_chunks);
>  cache_tree_init(&cctx->free_space);
> +	cache_tree_init(&cctx->free_space_initial);
>  }  void clean_convert_context(struct btrfs_convert_context
>  *cctx)

Did you forget the clean path? :)

---
Su