From 2ff04db5f4fbf28cf990804b4ed4ad2bd605e677 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Mon, 22 Aug 2016 16:32:24 +0200 Subject: btrfs-progs: two staged filesystem creation The filesystem existence on a device is manifested by the signature, during the mkfs process we write it first and then create other structures. Such filesystem is not valid and should not be registered during device scan nor listed among devices from blkid. This patch will introduce two staged creation. In the first phase, the signature is wrong, but recognized as a partially created filesystem (by open or scan helpers). Once we successfully create and write everything, we fixup the signature. At this point automated scanning should find a valid filesystem on all devices. We can also rely on the partially created filesystem to do better error handling during creation. We can just bail out and do not need to clean up. The partial signature is '!BHRfS_M', can be shown by btrfs inspect-internal dump-super -F image Reviewed-by: Anand Jain Signed-off-by: David Sterba --- btrfs-convert.c | 7 +++++-- ctree.h | 1 + disk-io.c | 35 +++++++++++++++++++++++++++++------ disk-io.h | 11 ++++++++++- mkfs.c | 7 ++++++- utils.c | 10 ++++++++-- 6 files changed, 59 insertions(+), 12 deletions(-) diff --git a/btrfs-convert.c b/btrfs-convert.c index a8852d61..b34a413d 100644 --- a/btrfs-convert.c +++ b/btrfs-convert.c @@ -2345,7 +2345,7 @@ static int do_convert(const char *devname, int datacsum, int packing, } root = open_ctree_fd(fd, devname, mkfs_cfg.super_bytenr, - OPEN_CTREE_WRITES); + OPEN_CTREE_WRITES | OPEN_CTREE_FS_PARTIAL); if (!root) { fprintf(stderr, "unable to open ctree\n"); goto fail; @@ -2431,11 +2431,14 @@ static int do_convert(const char *devname, int datacsum, int packing, } is_btrfs = 1; - root = open_ctree_fd(fd, devname, 0, OPEN_CTREE_WRITES); + root = open_ctree_fd(fd, devname, 0, + OPEN_CTREE_WRITES | OPEN_CTREE_FS_PARTIAL); if (!root) { fprintf(stderr, "unable to open ctree\n"); goto fail; } + root->fs_info->finalize_on_close = 1; + close_ctree(root); close(fd); printf("conversion complete.\n"); diff --git a/ctree.h b/ctree.h index 89e47abd..d0569835 100644 --- a/ctree.h +++ b/ctree.h @@ -1032,6 +1032,7 @@ struct btrfs_fs_info { unsigned int ignore_chunk_tree_error:1; unsigned int avoid_meta_chunk_alloc:1; unsigned int avoid_sys_chunk_alloc:1; + unsigned int finalize_on_close:1; int (*free_extent_hook)(struct btrfs_trans_handle *trans, struct btrfs_root *root, diff --git a/disk-io.c b/disk-io.c index 4874f068..ca4578f7 100644 --- a/disk-io.c +++ b/disk-io.c @@ -1225,6 +1225,7 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path, struct extent_buffer *eb; int ret; int oflags; + unsigned sbflags = SBREAD_DEFAULT; if (sb_bytenr == 0) sb_bytenr = BTRFS_SUPER_INFO_OFFSET; @@ -1247,9 +1248,18 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path, if (flags & OPEN_CTREE_IGNORE_CHUNK_TREE_ERROR) fs_info->ignore_chunk_tree_error = 1; - ret = btrfs_scan_fs_devices(fp, path, &fs_devices, sb_bytenr, - (flags & OPEN_CTREE_RECOVER_SUPER) ? SBREAD_RECOVER : SBREAD_DEFAULT, - (flags & OPEN_CTREE_NO_DEVICES)); + if ((flags & OPEN_CTREE_RECOVER_SUPER) + && (flags & OPEN_CTREE_FS_PARTIAL)) { + fprintf(stderr, + "cannot open a partially created filesystem for recovery"); + goto out; + } + + if (flags & OPEN_CTREE_FS_PARTIAL) + sbflags = SBREAD_PARTIAL; + + ret = btrfs_scan_fs_devices(fp, path, &fs_devices, sb_bytenr, sbflags, + (flags & OPEN_CTREE_NO_DEVICES)); if (ret) goto out; @@ -1272,7 +1282,7 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path, sb_bytenr, SBREAD_RECOVER); else ret = btrfs_read_dev_super(fp, disk_super, sb_bytenr, - SBREAD_DEFAULT); + sbflags); if (ret) { printk("No valid btrfs found\n"); goto out_devices; @@ -1401,8 +1411,12 @@ static int check_super(struct btrfs_super_block *sb, unsigned sbflags) int csum_size; if (btrfs_super_magic(sb) != BTRFS_MAGIC) { - error("superblock magic doesn't match"); - return -EIO; + if (btrfs_super_magic(sb) == BTRFS_MAGIC_PARTIAL) { + if (!(sbflags & SBREAD_PARTIAL)) { + error("superblock magic doesn't match"); + return -EIO; + } + } } csum_type = btrfs_super_csum_type(sb); @@ -1747,6 +1761,15 @@ int close_ctree_fs_info(struct btrfs_fs_info *fs_info) write_ctree_super(trans, root); btrfs_free_transaction(root, trans); } + + if (fs_info->finalize_on_close) { + btrfs_set_super_magic(fs_info->super_copy, BTRFS_MAGIC); + root->fs_info->finalize_on_close = 0; + ret = write_all_supers(root); + if (ret) + fprintf(stderr, + "failed to write new super block err %d\n", ret); + } btrfs_free_block_groups(fs_info); free_fs_roots_tree(&fs_info->fs_root_tree); diff --git a/disk-io.h b/disk-io.h index 153ef1f4..a73dede1 100644 --- a/disk-io.h +++ b/disk-io.h @@ -61,7 +61,10 @@ enum btrfs_open_ctree_flags { * It's useful for chunk corruption case. * Makes no sense for open_ctree variants returning btrfs_root. */ - OPEN_CTREE_IGNORE_CHUNK_TREE_ERROR = (1 << 11) + OPEN_CTREE_IGNORE_CHUNK_TREE_ERROR = (1 << 11), + + /* Allow to open a partially created filesystem */ + OPEN_CTREE_FS_PARTIAL = (1 << 12), }; /* @@ -71,6 +74,12 @@ enum btrfs_read_sb_flags { SBREAD_DEFAULT = 0, /* Reading superblock during recovery */ SBREAD_RECOVER = (1 << 0), + + /* + * Read superblock with the fake signature, cannot be used with + * SBREAD_RECOVER + */ + SBREAD_PARTIAL = (1 << 1), }; static inline u64 btrfs_sb_offset(int mirror) diff --git a/mkfs.c b/mkfs.c index 0b081dd4..ee5a30da 100644 --- a/mkfs.c +++ b/mkfs.c @@ -1708,7 +1708,7 @@ int main(int argc, char **argv) exit(1); } - root = open_ctree(file, 0, OPEN_CTREE_WRITES); + root = open_ctree(file, 0, OPEN_CTREE_WRITES | OPEN_CTREE_FS_PARTIAL); if (!root) { error("open ctree failed"); close(fd); @@ -1858,6 +1858,11 @@ raid_groups: list_all_devices(root); } + /* + * The filesystem is now fully set up, commit the remaining changes and + * fix the signature as the last step before closing the devices. + */ + root->fs_info->finalize_on_close = 1; out: ret = close_ctree(root); BUG_ON(ret); diff --git a/utils.c b/utils.c index e7195b53..cec7c738 100644 --- a/utils.c +++ b/utils.c @@ -238,6 +238,9 @@ static inline int write_temp_super(int fd, struct btrfs_super_block *sb, * * For now sys chunk array will be empty and dev_item is empty too. * They will be re-initialized at temp chunk tree setup. + * + * The superblock signature is not valid, denotes a partially created + * filesystem, needs to be finalized. */ static int setup_temp_super(int fd, struct btrfs_mkfs_config *cfg, u64 root_bytenr, u64 chunk_bytenr) @@ -276,7 +279,7 @@ static int setup_temp_super(int fd, struct btrfs_mkfs_config *cfg, 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_magic(super, BTRFS_MAGIC_PARTIAL); btrfs_set_super_generation(super, 1); btrfs_set_super_root(super, root_bytenr); btrfs_set_super_chunk_root(super, chunk_bytenr); @@ -1004,6 +1007,9 @@ out: /* * @fs_uuid - if NULL, generates a UUID, returns back the new filesystem UUID + * + * The superblock signature is not valid, denotes a partially created + * filesystem, needs to be finalized. */ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg, struct btrfs_convert_context *cctx) @@ -1064,7 +1070,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg, btrfs_set_super_bytenr(&super, cfg->blocks[0]); btrfs_set_super_num_devices(&super, 1); - btrfs_set_super_magic(&super, BTRFS_MAGIC); + btrfs_set_super_magic(&super, BTRFS_MAGIC_PARTIAL); btrfs_set_super_generation(&super, 1); btrfs_set_super_root(&super, cfg->blocks[1]); btrfs_set_super_chunk_root(&super, cfg->blocks[3]); -- cgit v1.2.3