diff options
Diffstat (limited to 'libblkid/src/superblocks/btrfs.c')
| -rw-r--r-- | libblkid/src/superblocks/btrfs.c | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/libblkid/src/superblocks/btrfs.c b/libblkid/src/superblocks/btrfs.c new file mode 100644 index 0000000..78d767d --- /dev/null +++ b/libblkid/src/superblocks/btrfs.c @@ -0,0 +1,259 @@ +/* + * Copyright (C) 2009 Karel Zak <kzak@redhat.com> + * + * This file may be redistributed under the terms of the + * GNU Lesser General Public License. + */ +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <stdint.h> +#include <stdbool.h> +#include <assert.h> +#include <inttypes.h> + +#ifdef HAVE_LINUX_BLKZONED_H +#include <linux/blkzoned.h> +#endif + +#include "superblocks.h" + +struct btrfs_super_block { + uint8_t csum[32]; + uint8_t fsid[16]; + uint64_t bytenr; + uint64_t flags; + uint8_t magic[8]; + uint64_t generation; + uint64_t root; + uint64_t chunk_root; + uint64_t log_root; + uint64_t log_root_transid; + uint64_t total_bytes; + uint64_t bytes_used; + uint64_t root_dir_objectid; + uint64_t num_devices; + uint32_t sectorsize; + uint32_t nodesize; + uint32_t leafsize; + uint32_t stripesize; + uint32_t sys_chunk_array_size; + uint64_t chunk_root_generation; + uint64_t compat_flags; + uint64_t compat_ro_flags; + uint64_t incompat_flags; + uint16_t csum_type; + uint8_t root_level; + uint8_t chunk_root_level; + uint8_t log_root_level; + struct btrfs_dev_item { + uint64_t devid; + uint64_t total_bytes; + uint64_t bytes_used; + uint32_t io_align; + uint32_t io_width; + uint32_t sector_size; + uint64_t type; + uint64_t generation; + uint64_t start_offset; + uint32_t dev_group; + uint8_t seek_speed; + uint8_t bandwidth; + uint8_t uuid[16]; + uint8_t fsid[16]; + } __attribute__ ((__packed__)) dev_item; + uint8_t label[256]; +} __attribute__ ((__packed__)); + +#define BTRFS_SUPER_INFO_SIZE 4096 + +/* Number of superblock log zones */ +#define BTRFS_NR_SB_LOG_ZONES 2 + +/* Introduce some macros and types to unify the code with kernel side */ +#define SECTOR_SHIFT 9 + +typedef uint64_t sector_t; + +#ifdef HAVE_LINUX_BLKZONED_H +static int sb_write_pointer(blkid_probe pr, struct blk_zone *zones, uint64_t *wp_ret) +{ + bool empty[BTRFS_NR_SB_LOG_ZONES]; + bool full[BTRFS_NR_SB_LOG_ZONES]; + sector_t sector; + + assert(zones[0].type != BLK_ZONE_TYPE_CONVENTIONAL && + zones[1].type != BLK_ZONE_TYPE_CONVENTIONAL); + + empty[0] = zones[0].cond == BLK_ZONE_COND_EMPTY; + empty[1] = zones[1].cond == BLK_ZONE_COND_EMPTY; + full[0] = zones[0].cond == BLK_ZONE_COND_FULL; + full[1] = zones[1].cond == BLK_ZONE_COND_FULL; + + /* + * Possible states of log buffer zones + * + * Empty[0] In use[0] Full[0] + * Empty[1] * x 0 + * In use[1] 0 x 0 + * Full[1] 1 1 C + * + * Log position: + * *: Special case, no superblock is written + * 0: Use write pointer of zones[0] + * 1: Use write pointer of zones[1] + * C: Compare super blocks from zones[0] and zones[1], use the latest + * one determined by generation + * x: Invalid state + */ + + if (empty[0] && empty[1]) { + /* Special case to distinguish no superblock to read */ + *wp_ret = zones[0].start << SECTOR_SHIFT; + return -ENOENT; + } else if (full[0] && full[1]) { + /* Compare two super blocks */ + struct btrfs_super_block *super[BTRFS_NR_SB_LOG_ZONES]; + int i; + + for (i = 0; i < BTRFS_NR_SB_LOG_ZONES; i++) { + uint64_t bytenr; + + bytenr = ((zones[i].start + zones[i].len) + << SECTOR_SHIFT) - BTRFS_SUPER_INFO_SIZE; + + super[i] = (struct btrfs_super_block *) + blkid_probe_get_buffer(pr, bytenr, BTRFS_SUPER_INFO_SIZE); + if (!super[i]) + return -EIO; + DBG(LOWPROBE, ul_debug("(btrfs) checking #%d zone " + "[start=%" PRIu64", len=%" PRIu64", sb-offset=%" PRIu64"]", + i, (uint64_t) zones[i].start, + (uint64_t) zones[i].len, bytenr)); + } + + if (super[0]->generation > super[1]->generation) + sector = zones[1].start; + else + sector = zones[0].start; + } else if (!full[0] && (empty[1] || full[1])) { + sector = zones[0].wp; + } else if (full[0]) { + sector = zones[1].wp; + } else { + return -EUCLEAN; + } + *wp_ret = sector << SECTOR_SHIFT; + + DBG(LOWPROBE, ul_debug("(btrfs) write pointer: %" PRIu64" sector", sector)); + return 0; +} + +static int sb_log_offset(blkid_probe pr, uint64_t *bytenr_ret) +{ + uint32_t zone_num = 0; + uint32_t zone_size_sector; + struct blk_zone_report *rep; + struct blk_zone *zones; + int ret; + int i; + uint64_t wp; + + + zone_size_sector = pr->zone_size >> SECTOR_SHIFT; + rep = blkdev_get_zonereport(pr->fd, zone_num * zone_size_sector, 2); + if (!rep) { + ret = -errno; + goto out; + } + zones = (struct blk_zone *)(rep + 1); + + /* + * Use the head of the first conventional zone, if the zones + * contain one. + */ + for (i = 0; i < BTRFS_NR_SB_LOG_ZONES; i++) { + if (zones[i].type == BLK_ZONE_TYPE_CONVENTIONAL) { + DBG(LOWPROBE, ul_debug("(btrfs) checking conventional zone")); + *bytenr_ret = zones[i].start << SECTOR_SHIFT; + ret = 0; + goto out; + } + } + + ret = sb_write_pointer(pr, zones, &wp); + if (ret != -ENOENT && ret) { + ret = 1; + goto out; + } + if (ret != -ENOENT) { + if (wp == zones[0].start << SECTOR_SHIFT) + wp = (zones[1].start + zones[1].len) << SECTOR_SHIFT; + wp -= BTRFS_SUPER_INFO_SIZE; + } + *bytenr_ret = wp; + + ret = 0; +out: + free(rep); + + return ret; +} +#endif + +static int probe_btrfs(blkid_probe pr, const struct blkid_idmag *mag) +{ + struct btrfs_super_block *bfs; + + if (pr->zone_size) { +#ifdef HAVE_LINUX_BLKZONED_H + uint64_t offset = 0; + int ret; + + ret = sb_log_offset(pr, &offset); + if (ret) + return ret; + bfs = (struct btrfs_super_block *) + blkid_probe_get_buffer(pr, offset, + sizeof(struct btrfs_super_block)); +#else + /* Nothing can be done */ + return 1; +#endif + } else { + bfs = blkid_probe_get_sb(pr, mag, struct btrfs_super_block); + } + if (!bfs) + return errno ? -errno : 1; + + if (*bfs->label) + blkid_probe_set_label(pr, + (unsigned char *) bfs->label, + sizeof(bfs->label)); + + blkid_probe_set_uuid(pr, bfs->fsid); + blkid_probe_set_uuid_as(pr, bfs->dev_item.uuid, "UUID_SUB"); + blkid_probe_set_block_size(pr, le32_to_cpu(bfs->sectorsize)); + + return 0; +} + +const struct blkid_idinfo btrfs_idinfo = +{ + .name = "btrfs", + .usage = BLKID_USAGE_FILESYSTEM, + .probefunc = probe_btrfs, + .minsz = 1024 * 1024, + .magics = + { + { .magic = "_BHRfS_M", .len = 8, .sboff = 0x40, .kboff = 64 }, + /* For zoned btrfs */ + { .magic = "_BHRfS_M", .len = 8, .sboff = 0x40, + .is_zoned = 1, .zonenum = 0, .kboff_inzone = 0 }, + { .magic = "_BHRfS_M", .len = 8, .sboff = 0x40, + .is_zoned = 1, .zonenum = 1, .kboff_inzone = 0 }, + { NULL } + } +}; + |