}
static const char * const cmd_resize_usage[] = {
- "btrfs filesystem resize [devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max <path>",
+ "btrfs filesystem resize [devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max
|[devid:]get_min_size <path>",
"Resize a filesystem",
"If 'max' is passed, the filesystem will occupy all available space",
"on the device 'devid'.",
+ "If 'get_min_size' is passed, return the minimum size the device can",
+ "be shrunk to.",
"[kK] means KiB, which denotes 1KiB = 1024B, 1MiB = 1024KiB, etc.",
NULL
};
+struct dev_extent_elem {
+ u64 start;
+ /* inclusive end */
+ u64 end;
+ struct list_head list;
+};
+
+static int add_dev_extent(struct list_head *list,
+ const u64 start, const u64 end,
+ const int append)
+{
+ struct dev_extent_elem *e;
+
+ e = malloc(sizeof(*e));
+ if (!e)
+ return -ENOMEM;
+
+ e->start = start;
+ e->end = end;
+
+ if (append)
+ list_add_tail(&e->list, list);
+ else
+ list_add(&e->list, list);
+
+ return 0;
+}
+
+static void free_dev_extent_list(struct list_head *list)
+{
+ while (!list_empty(list)) {
+ struct dev_extent_elem *e;
+
+ e = list_first_entry(list, struct dev_extent_elem, list);
+ list_del(&e->list);
+ free(e);
+ }
+}
+
+static int hole_includes_sb_mirror(const u64 start, const u64 end)
+{
+ int i;
+ int ret = 0;
+
+ for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+ u64 bytenr = btrfs_sb_offset(i);
+
+ if (bytenr >= start && bytenr <= end) {
+ ret = 1;
+ break;
+ }
+ }
+
+ return ret;
+}
+
+static void adjust_dev_min_size(struct list_head *extents,
+ struct list_head *holes,
+ u64 *min_size)
+{
+ /*
+ * If relocation of the block group of a device extent must happen (see
+ * below) scratch space is used for the relocation. So track here the
+ * size of the largest device extent that has to be relocated. We track
+ * only the largest and not the sum of the sizes of all relocated block
+ * groups because after each block group is relocated the running
+ * transaction is committed so that pinned space is released.
+ */
+ u64 scratch_space = 0;
+
+ /*
+ * List of device extents is sorted by descending order of the extent's
+ * end offset. If some extent goes beyond the computed minimum size,
+ * which initially matches the sum of the lenghts of all extents,
+ * we need to check if the extent can be relocated to an hole in the
+ * device between [0, *min_size[ (which is what the resize ioctl does).
+ */
+ while (!list_empty(extents)) {
+ struct dev_extent_elem *e;
+ struct dev_extent_elem *h;
+ int found = 0;
+ u64 extent_len;
+ u64 hole_len = 0;
+
+ e = list_first_entry(extents, struct dev_extent_elem, list);
+ if (e->end <= *min_size)
+ break;
+
+ /*
+ * Our extent goes beyond the computed *min_size. See if we can
+ * find a hole large enough to relocate it to. If not we must stop
+ * and set *min_size to the end of the extent.
+ */
+ extent_len = e->end - e->start + 1;
+ list_for_each_entry(h, holes, list) {
+ hole_len = h->end - h->start + 1;
+ if (hole_len >= extent_len) {
+ found = 1;
+ break;
+ }
+ }
+
+ if (!found) {
+ *min_size = e->end + 1;
+ break;
+ }
+
+ /*
+ * If the hole found contains the location for a superblock
+ * mirror, we are pessimistic and require allocating one
+ * more extent of the same size. This is because the block
+ * group could be in the worst case used by a single extent
+ * with a size >= (block_group.length - superblock.size).
+ */
+ if (hole_includes_sb_mirror(h->start,
+ h->start + extent_len - 1))
+ *min_size += extent_len;
+
+ if (hole_len > extent_len) {
+ h->start += extent_len;
+ } else {
+ list_del(&h->list);
+ free(h);
+ }
+
+ list_del(&e->list);
+ free(e);
+
+ if (extent_len > scratch_space)
+ scratch_space = extent_len;
+ }
+
+ if (scratch_space) {
+ *min_size += scratch_space;
+ /*
+ * Chunk allocation requires inserting/updating items in the
+ * chunk tree, so often this can lead to the need of allocating
+ * a new system chunk too, which has a maximum size of 32Mb.
+ */
+ *min_size += 32 * 1024 * 1024;
+ }
+}
+
+static int get_min_size(int fd, DIR *dirstream, const char *amount)
+{
+ int ret = 1;
+ char *p = strstr(amount, ":");
+ u64 devid = 1;
+ /*
+ * Device allocations starts at 1Mb or at the value passed through the
+ * mount option alloc_start if it's bigger than 1Mb. The alloc_start
+ * option is used for debugging and testing only, and recently the
+ * possibility of deprecating/removing it has been discussed, so we
+ * ignore it here.
+ */
+ u64 min_size = 1 * 1024 * 1024ull;
+ struct btrfs_ioctl_search_args args;
+ struct btrfs_ioctl_search_key *sk = &args.key;
+ u64 last_pos = (u64)-1;
+ LIST_HEAD(extents);
+ LIST_HEAD(holes);
+
+ if (p && sscanf(amount, "%llu:get_min_size", &devid) != 1) {
+ fprintf(stderr, "Invalid parameter: %s\n", amount);
+ goto out;
+ }
+
+ memset(&args, 0, sizeof(args));
+ sk->tree_id = BTRFS_DEV_TREE_OBJECTID;
+ sk->min_objectid = devid;
+ sk->max_objectid = devid;
+ sk->max_type = BTRFS_DEV_EXTENT_KEY;
+ sk->min_type = BTRFS_DEV_EXTENT_KEY;
+ sk->min_offset = 0;
+ sk->max_offset = (u64)-1;
+ sk->min_transid = 0;
+ sk->max_transid = (u64)-1;
+ sk->nr_items = 4096;
+
+ while (1) {
+ int i;
+ struct btrfs_ioctl_search_header *sh;
+ unsigned long off = 0;
+
+ ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
+ if (ret < 0) {
+ fprintf(stderr,
+ "Error invoking tree search ioctl: %s\n",
+ strerror(errno));
+ ret = 1;
+ goto out;
+ }
+
+ if (sk->nr_items == 0)
+ break;
+
+ for (i = 0; i < sk->nr_items; i++) {
+ struct btrfs_dev_extent *extent;
+ u64 len;
+
+ sh = (struct btrfs_ioctl_search_header *)(args.buf +
+ off);
+ off += sizeof(*sh);
+ extent = (struct btrfs_dev_extent *)(args.buf + off);
+ off += sh->len;
+
+ sk->min_objectid = sh->objectid;
+ sk->min_type = sh->type;
+ sk->min_offset = sh->offset + 1;
+
+ if (sh->objectid != devid ||
+ sh->type != BTRFS_DEV_EXTENT_KEY)
+ continue;
+
+ len = btrfs_stack_dev_extent_length(extent);
+ min_size += len;
+ ret = add_dev_extent(&extents, sh->offset,
+ sh->offset + len - 1, 0);
+
+ if (!ret && last_pos != (u64)-1 &&
+ last_pos != sh->offset)
+ ret = add_dev_extent(&holes, last_pos,
+ sh->offset - 1, 1);
+ if (ret) {
+ fprintf(stderr, "Error: %s\n", strerror(-ret));
+ ret = 1;
+ goto out;
+ }
+
+ last_pos = sh->offset + len;
+ }
+
+ if (sk->min_type != BTRFS_DEV_EXTENT_KEY ||
+ sk->min_objectid != devid)
+ break;
+ }
+
+ adjust_dev_min_size(&extents, &holes, &min_size);
+ printf("%llu bytes (%s)\n", min_size, pretty_size(min_size));
+ ret = 0;
+out:
+ close_file_or_dir(fd, dirstream);
+ free_dev_extent_list(&extents);
+ free_dev_extent_list(&holes);
+
+ return ret;
+}
+
static int cmd_resize(int argc, char **argv)
{
struct btrfs_ioctl_vol_args args;
return 1;
}
+ if (strstr(amount, "get_min_size"))
+ return get_min_size(fd, dirstream, amount);
+
printf("Resize '%s' of '%s'\n", path, amount);
memset(&args, 0, sizeof(args));
strncpy_null(args.name, amount);
projects / platform / upstream / btrfs-progs.git / blobdiff