Btrfs: superblock duplication
This patch implements superblock duplication. Superblocks
are stored at offset 16K, 64M and 256G on every devices.
Spaces used by superblocks are preserved by the allocator,
which uses a reverse mapping function to find the logical
addresses that correspond to superblocks. Thank you,
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2049d17..a79b3cc 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -423,15 +423,11 @@
}
set_blocksize(bdev, 4096);
- bh = __bread(bdev, BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
+ bh = btrfs_read_dev_super(bdev);
if (!bh)
goto error_close;
disk_super = (struct btrfs_super_block *)bh->b_data;
- if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
- sizeof(disk_super->magic)))
- goto error_brelse;
-
devid = le64_to_cpu(disk_super->dev_item.devid);
if (devid != device->devid)
goto error_brelse;
@@ -529,17 +525,12 @@
ret = set_blocksize(bdev, 4096);
if (ret)
goto error_close;
- bh = __bread(bdev, BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
+ bh = btrfs_read_dev_super(bdev);
if (!bh) {
ret = -EIO;
goto error_close;
}
disk_super = (struct btrfs_super_block *)bh->b_data;
- if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
- sizeof(disk_super->magic))) {
- ret = -EINVAL;
- goto error_brelse;
- }
devid = le64_to_cpu(disk_super->dev_item.devid);
transid = btrfs_super_generation(disk_super);
if (disk_super->label[0])
@@ -553,7 +544,6 @@
printk("devid %Lu transid %Lu %s\n", devid, transid, path);
ret = device_list_add(path, disk_super, devid, fs_devices_ret);
-error_brelse:
brelse(bh);
error_close:
close_bdev_exclusive(bdev, flags);
@@ -1016,17 +1006,12 @@
}
set_blocksize(bdev, 4096);
- bh = __bread(bdev, BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
+ bh = btrfs_read_dev_super(bdev);
if (!bh) {
ret = -EIO;
goto error_close;
}
disk_super = (struct btrfs_super_block *)bh->b_data;
- if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
- sizeof(disk_super->magic))) {
- ret = -ENOENT;
- goto error_brelse;
- }
devid = le64_to_cpu(disk_super->dev_item.devid);
dev_uuid = disk_super->dev_item.uuid;
device = btrfs_find_device(root, devid, dev_uuid,
@@ -2563,6 +2548,88 @@
mirror_num, NULL);
}
+int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
+ u64 chunk_start, u64 physical, u64 devid,
+ u64 **logical, int *naddrs, int *stripe_len)
+{
+ struct extent_map_tree *em_tree = &map_tree->map_tree;
+ struct extent_map *em;
+ struct map_lookup *map;
+ u64 *buf;
+ u64 bytenr;
+ u64 length;
+ u64 stripe_nr;
+ int i, j, nr = 0;
+
+ spin_lock(&em_tree->lock);
+ em = lookup_extent_mapping(em_tree, chunk_start, 1);
+ spin_unlock(&em_tree->lock);
+
+ BUG_ON(!em || em->start != chunk_start);
+ map = (struct map_lookup *)em->bdev;
+
+ length = em->len;
+ if (map->type & BTRFS_BLOCK_GROUP_RAID10)
+ do_div(length, map->num_stripes / map->sub_stripes);
+ else if (map->type & BTRFS_BLOCK_GROUP_RAID0)
+ do_div(length, map->num_stripes);
+
+ buf = kzalloc(sizeof(u64) * map->num_stripes, GFP_NOFS);
+ BUG_ON(!buf);
+
+ for (i = 0; i < map->num_stripes; i++) {
+ if (devid && map->stripes[i].dev->devid != devid)
+ continue;
+ if (map->stripes[i].physical > physical ||
+ map->stripes[i].physical + length <= physical)
+ continue;
+
+ stripe_nr = physical - map->stripes[i].physical;
+ do_div(stripe_nr, map->stripe_len);
+
+ if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
+ stripe_nr = stripe_nr * map->num_stripes + i;
+ do_div(stripe_nr, map->sub_stripes);
+ } else if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
+ stripe_nr = stripe_nr * map->num_stripes + i;
+ }
+ bytenr = chunk_start + stripe_nr * map->stripe_len;
+ for (j = 0; j < nr; j++) {
+ if (buf[j] == bytenr)
+ break;
+ }
+ if (j == nr)
+ buf[nr++] = bytenr;
+ }
+
+ for (i = 0; i > nr; i++) {
+ struct btrfs_multi_bio *multi;
+ struct btrfs_bio_stripe *stripe;
+ int ret;
+
+ length = 1;
+ ret = btrfs_map_block(map_tree, WRITE, buf[i],
+ &length, &multi, 0);
+ BUG_ON(ret);
+
+ stripe = multi->stripes;
+ for (j = 0; j < multi->num_stripes; j++) {
+ if (stripe->physical >= physical &&
+ physical < stripe->physical + length)
+ break;
+ }
+ BUG_ON(j >= multi->num_stripes);
+ kfree(multi);
+ }
+
+ *logical = buf;
+ *naddrs = nr;
+ *stripe_len = map->stripe_len;
+
+ free_extent_map(em);
+ return 0;
+}
+
int btrfs_unplug_page(struct btrfs_mapping_tree *map_tree,
u64 logical, struct page *page)
{
@@ -3003,7 +3070,7 @@
return read_one_dev(root, buf, dev_item);
}
-int btrfs_read_sys_array(struct btrfs_root *root)
+int btrfs_read_sys_array(struct btrfs_root *root, u64 sb_bytenr)
{
struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
struct extent_buffer *sb;
@@ -3018,7 +3085,7 @@
u32 cur;
struct btrfs_key key;
- sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
+ sb = btrfs_find_create_tree_block(root, sb_bytenr,
BTRFS_SUPER_INFO_SIZE);
if (!sb)
return -ENOMEM;
