Hello Anand,
> (This patch is for review and comments only)
>
> This patch provides a way to know how much space can be
> relinquished if when subvol /snapshot is deleted. With
> this sys admin can make better judgments in managing the
> filesystem when fs is near full.
>
I think this is really *helpful* since users can not really know how much
space(Exclusive) in a subvolume .
Thanks,
Wang
> as shown below the parameter 'sole space' indicates the size
> which is freed when subvol is deleted. (any other better
> term for this?, pls suggest).
> ---------------------
> btrfs su show /btrfs/sv1
> /btrfs/sv1
> Name: sv1
> uuid: b078ba48-d4a5-2f49-ac03-9bd1d56cc768
> Parent uuid: -
> Creation time: 2013-09-13 18:17:32
> Object ID: 257
> Generation (Gen): 18
> Gen at creation: 17
> Parent: 5
> Top Level: 5
> Flags: -
> Sole space: 1.56MiB <----
> Snapshot(s):
>
> btrfs su snap /btrfs/sv1 /btrfs/ss2
> Create a snapshot of '/btrfs/sv1' in '/btrfs/ss2'
>
> btrfs su show /btrfs/sv1
> /btrfs/sv1
> Name: sv1
> uuid: b078ba48-d4a5-2f49-ac03-9bd1d56cc768
> Parent uuid: -
> Creation time: 2013-09-13 18:17:32
> Object ID: 257
> Generation (Gen): 19
> Gen at creation: 17
> Parent: 5
> Top Level: 5
> Flags: -
> Sole space: 0.00 <-----
> Snapshot(s):
> ss2
> ---------------------
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> ---
> cmds-subvolume.c | 5 ++
> utils.c | 154 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> utils.h | 1 +
> 3 files changed, 160 insertions(+)
>
> diff --git a/cmds-subvolume.c b/cmds-subvolume.c
> index de246ab..2b02d66 100644
> --- a/cmds-subvolume.c
> +++ b/cmds-subvolume.c
> @@ -809,6 +809,7 @@ static int cmd_subvol_show(int argc, char **argv)
> int fd = -1, mntfd = -1;
> int ret = 1;
> DIR *dirstream1 = NULL, *dirstream2 = NULL;
> + u64 freeable_bytes;
>
> if (check_argc_exact(argc, 2))
> usage(cmd_subvol_show_usage);
> @@ -878,6 +879,8 @@ static int cmd_subvol_show(int argc, char **argv)
> goto out;
> }
>
> + freeable_bytes = get_subvol_freeable_bytes(fd);
> +
> ret = 0;
> /* print the info */
> printf("%s\n", fullpath);
> @@ -915,6 +918,8 @@ static int cmd_subvol_show(int argc, char **argv)
> else
> printf("\tFlags: \t\t\t-\n");
>
> + printf("\tSole space: \t\t%s\n",
> + pretty_size(freeable_bytes));
> /* print the snapshots of the given subvol if any*/
> printf("\tSnapshot(s):\n");
> filter_set = btrfs_list_alloc_filter_set();
> diff --git a/utils.c b/utils.c
> index 22c3310..f01d580 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -2019,3 +2019,157 @@ int is_dev_excl_op_free(int fd)
> ret = ioctl(fd, BTRFS_IOC_CHECK_DEV_EXCL_OPS, NULL);
> return ret > 0 ? ret : -errno;
> }
> +
> +/* gets the ref count for given extent
> + * 0 = didn't find the item
> + * n = number of references
> +*/
> +u64 get_extent_refcnt(int fd, u64 disk_blk)
> +{
> + int ret = 0, i, e;
> + struct btrfs_ioctl_search_args args;
> + struct btrfs_ioctl_search_key *sk = &args.key;
> + struct btrfs_ioctl_search_header sh;
> + unsigned long off = 0;
> +
> + memset(&args, 0, sizeof(args));
> +
> + sk->tree_id = BTRFS_EXTENT_TREE_OBJECTID;
> +
> + sk->min_type = BTRFS_EXTENT_ITEM_KEY;
> + sk->max_type = BTRFS_EXTENT_ITEM_KEY;
> +
> + sk->min_objectid = disk_blk;
> + sk->max_objectid = disk_blk;
> +
> + sk->max_offset = (u64)-1;
> + sk->max_transid = (u64)-1;
> +
> + while (1) {
> + sk->nr_items = 4096;
> +
> + ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
> + e = errno;
> + if (ret < 0) {
> + fprintf(stderr, "ERROR: search failed - %s\n",
> + strerror(e));
> + return 0;
> + }
> + if (sk->nr_items == 0)
> + break;
> +
> + off = 0;
> + for (i = 0; i < sk->nr_items; i++) {
> + struct btrfs_extent_item *ei;
> + u64 ref;
> +
> + memcpy(&sh, args.buf + off, sizeof(sh));
> + off += sizeof(sh);
> +
> + if (sh.type != BTRFS_EXTENT_ITEM_KEY) {
> + off += sh.len;
> + continue;
> + }
> +
> + ei = (struct btrfs_extent_item *)(args.buf + off);
> + ref = btrfs_stack_extent_refs(ei);
> + return ref;
> + }
> + sk->min_objectid = sh.objectid;
> + sk->min_offset = sh.offset;
> + sk->min_type = sh.type;
> + if (sk->min_offset < (u64)-1)
> + sk->min_offset++;
> + else if (sk->min_objectid < (u64)-1) {
> + sk->min_objectid++;
> + sk->min_offset = 0;
> + sk->min_type = 0;
> + } else
> + break;
> + }
> + return 0;
> +}
> +
> +u64 get_subvol_freeable_bytes(int fd)
> +{
> + int ret = 0, i, e;
> + struct btrfs_ioctl_search_args args;
> + struct btrfs_ioctl_search_key *sk = &args.key;
> + struct btrfs_ioctl_search_header sh;
> + unsigned long off = 0;
> + u64 size_bytes = 0;
> +
> + memset(&args, 0, sizeof(args));
> +
> + sk->tree_id = 0;
> +
> + sk->min_type = BTRFS_EXTENT_DATA_KEY;
> + sk->max_type = BTRFS_EXTENT_DATA_KEY;
> +
> + sk->max_objectid = (u64) -1;
> + sk->max_offset = (u64)-1;
> + sk->max_transid = (u64)-1;
> +
> + while (1) {
> + sk->nr_items = 4096;
> +
> + ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
> + e = errno;
> + if (ret < 0) {
> + fprintf(stderr, "ERROR: search failed - %s\n",
> + strerror(e));
> + return 0;
> + }
> + if (sk->nr_items == 0)
> + break;
> +
> + off = 0;
> + for (i = 0; i < sk->nr_items; i++) {
> + struct btrfs_file_extent_item *efi;
> + u64 disk_bytenr = 0;
> + u64 num_bytes = 0;
> + u64 refcnt;
> + u8 type;
> +
> + memcpy(&sh, args.buf + off, sizeof(sh));
> + off += sizeof(sh);
> +
> + if (sh.type != BTRFS_EXTENT_DATA_KEY) {
> + off += sh.len;
> + continue;
> + }
> +
> + efi = (struct btrfs_file_extent_item *)(args.buf + off);
> + type = btrfs_stack_file_extent_type(efi);
> +
> + if (type == BTRFS_FILE_EXTENT_INLINE) {
> + size_bytes +=
> + btrfs_stack_file_extent_ram_bytes(efi);
> + goto skip_extent_data;
> + }
> + disk_bytenr = btrfs_stack_file_extent_disk_bytenr(efi);
> + num_bytes = btrfs_stack_file_extent_num_bytes(efi);
> +
> + if (disk_bytenr) {
> + refcnt = get_extent_refcnt(fd, disk_bytenr);
> + if (refcnt == 1)
> + size_bytes += num_bytes;
> + }
> +skip_extent_data:
> + off += sh.len;
> + }
> + sk->min_objectid = sh.objectid;
> + sk->min_offset = sh.offset;
> + sk->min_type = sh.type;
> +
> + if (sk->min_offset < (u64)-1)
> + sk->min_offset++;
> + else if (sk->min_objectid < (u64)-1) {
> + sk->min_objectid++;
> + sk->min_offset = 0;
> + sk->min_type = 0;
> + } else
> + break;
> + }
> + return size_bytes;
> +}
> diff --git a/utils.h b/utils.h
> index 6952d34..0920bb3 100644
> --- a/utils.h
> +++ b/utils.h
> @@ -86,4 +86,5 @@ int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
> int verify);
> int get_btrfs_mount(const char *dev, char *mp, size_t mp_size);
> int is_dev_excl_op_free(int fd);
> +u64 get_subvol_freeable_bytes(int fd);
> #endif
> --
> 1.8.4.rc4.1.g0d8beaa
>
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