btrfs-progs: Introduce function to setup temporary superblock

Introduce a new function, setup_temp_super(), to setup temporary super
for make_btrfs_v2().

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
[ use __strncpy_null in setup_temp_super ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/utils.c b/utils.c
index 71b2200..368c32a 100644 (file)
--- a/utils.c
+++ b/utils.c
@@ -215,6 +215,97 @@ static int reserve_free_space(struct cache_tree *free_tree, u64 len,
        return 0;
 }
 
+static inline int write_temp_super(int fd, struct btrfs_super_block *sb,
+                                  u64 sb_bytenr)
+{
+       u32 crc = ~(u32)0;
+       int ret;
+
+       crc = btrfs_csum_data(NULL, (char *)sb + BTRFS_CSUM_SIZE, crc,
+                             BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
+       btrfs_csum_final(crc, (char *)&sb->csum[0]);
+       ret = pwrite(fd, sb, BTRFS_SUPER_INFO_SIZE, sb_bytenr);
+       if (ret < BTRFS_SUPER_INFO_SIZE)
+               ret = (ret < 0 ? -errno : -EIO);
+       else
+               ret = 0;
+       return ret;
+}
+
+/*
+ * Setup temporary superblock at cfg->super_bynter
+ * Needed info are extracted from cfg, and root_bytenr, chunk_bytenr
+ *
+ * For now sys chunk array will be empty and dev_item is empty too.
+ * They will be re-initialized at temp chunk tree setup.
+ */
+static int setup_temp_super(int fd, struct btrfs_mkfs_config *cfg,
+                           u64 root_bytenr, u64 chunk_bytenr)
+{
+       unsigned char chunk_uuid[BTRFS_UUID_SIZE];
+       char super_buf[BTRFS_SUPER_INFO_SIZE];
+       struct btrfs_super_block *super = (struct btrfs_super_block *)super_buf;
+       int ret;
+
+       /*
+        * We rely on cfg->chunk_uuid and cfg->fs_uuid to pass uuid
+        * for other functions.
+        * Caller must allocate space for them
+        */
+       BUG_ON(!cfg->chunk_uuid || !cfg->fs_uuid);
+       memset(super_buf, 0, BTRFS_SUPER_INFO_SIZE);
+       cfg->num_bytes = round_down(cfg->num_bytes, cfg->sectorsize);
+
+       if (cfg->fs_uuid && *cfg->fs_uuid) {
+               if (uuid_parse(cfg->fs_uuid, super->fsid) != 0) {
+                       error("cound not parse UUID: %s", cfg->fs_uuid);
+                       ret = -EINVAL;
+                       goto out;
+               }
+               if (!test_uuid_unique(cfg->fs_uuid)) {
+                       error("non-unique UUID: %s", cfg->fs_uuid);
+                       ret = -EINVAL;
+                       goto out;
+               }
+       } else {
+               uuid_generate(super->fsid);
+               uuid_unparse(super->fsid, cfg->fs_uuid);
+       }
+       uuid_generate(chunk_uuid);
+       uuid_unparse(chunk_uuid, cfg->chunk_uuid);
+
+       btrfs_set_super_bytenr(super, cfg->super_bytenr);
+       btrfs_set_super_num_devices(super, 1);
+       btrfs_set_super_magic(super, BTRFS_MAGIC);
+       btrfs_set_super_generation(super, 1);
+       btrfs_set_super_root(super, root_bytenr);
+       btrfs_set_super_chunk_root(super, chunk_bytenr);
+       btrfs_set_super_total_bytes(super, cfg->num_bytes);
+       /*
+        * Temporary filesystem will only have 6 tree roots:
+        * chunk tree, root tree, extent_tree, device tree, fs tree
+        * and csum tree.
+        */
+       btrfs_set_super_bytes_used(super, 6 * cfg->nodesize);
+       btrfs_set_super_sectorsize(super, cfg->sectorsize);
+       btrfs_set_super_leafsize(super, cfg->nodesize);
+       btrfs_set_super_nodesize(super, cfg->nodesize);
+       btrfs_set_super_stripesize(super, cfg->stripesize);
+       btrfs_set_super_csum_type(super, BTRFS_CSUM_TYPE_CRC32);
+       btrfs_set_super_chunk_root(super, chunk_bytenr);
+       btrfs_set_super_cache_generation(super, -1);
+       btrfs_set_super_incompat_flags(super, cfg->features);
+       if (cfg->label)
+               __strncpy_null(super->label, cfg->label, BTRFS_LABEL_SIZE - 1);
+
+       /* Sys chunk array will be re-initialized at chunk tree init time */
+       super->sys_chunk_array_size = 0;
+
+       ret = write_temp_super(fd, super, cfg->super_bytenr);
+out:
+       return ret;
+}
+
 /*
  * Improved version of make_btrfs().
  *
@@ -233,6 +324,10 @@ static int make_convert_btrfs(int fd, struct btrfs_mkfs_config *cfg,
        struct cache_tree *used = &cctx->used;
        u64 sys_chunk_start;
        u64 meta_chunk_start;
+       /* chunk tree bytenr, in system chunk */
+       u64 chunk_bytenr;
+       /* metadata trees bytenr, in metadata chunk */
+       u64 root_bytenr;
        int ret;
 
        /* Shouldn't happen */
@@ -263,6 +358,27 @@ static int make_convert_btrfs(int fd, struct btrfs_mkfs_config *cfg,
        if (ret < 0)
                goto out;
 
+       /*
+        * Inside the allocated metadata chunk, the layout will be:
+        *  | offset            | contents      |
+        *  -------------------------------------
+        *  | +0                | tree root     |
+        *  | +nodesize         | extent root   |
+        *  | +nodesize * 2     | device root   |
+        *  | +nodesize * 3     | fs tree       |
+        *  | +nodesize * 4     | csum tree     |
+        *  -------------------------------------
+        * Inside the allocated system chunk, the layout will be:
+        *  | offset            | contents      |
+        *  -------------------------------------
+        *  | +0                | chunk root    |
+        *  -------------------------------------
+        */
+       chunk_bytenr = sys_chunk_start;
+       root_bytenr = meta_chunk_start;
+       ret = setup_temp_super(fd, cfg, root_bytenr, chunk_bytenr);
+       if (ret < 0)
+               goto out;
 out:
        return ret;
 }