btrfs-progs: convert: Fix bugs in backup superblock migration

[platform/upstream/btrfs-progs.git] / btrfs-convert.c

diff --git a/btrfs-convert.c b/btrfs-convert.c
index f78bfbf..7cac304 100644 (file)
--- a/btrfs-convert.c
+++ b/btrfs-convert.c
@@ -1263,12 +1263,55 @@ static int create_image_file_range(struct btrfs_trans_handle *trans,
        struct btrfs_block_group_cache *bg_cache;
        u64 len = *ret_len;
        u64 disk_bytenr;
+       int i;
        int ret;
 
        BUG_ON(bytenr != round_down(bytenr, root->sectorsize));
        BUG_ON(len != round_down(len, root->sectorsize));
        len = min_t(u64, len, BTRFS_MAX_EXTENT_SIZE);
 
+       /*
+        * Skip sb ranges first
+        * [0, 1M), [sb_offset(1), +64K), [sb_offset(2), +64K].
+        *
+        * Or we will insert a hole into current image file, and later
+        * migrate block will fail as there is already a file extent.
+        */
+       if (bytenr < 1024 * 1024) {
+               *ret_len = 1024 * 1024 - bytenr;
+               return 0;
+       }
+       for (i = 1; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+               u64 cur = btrfs_sb_offset(i);
+
+               if (bytenr >= cur && bytenr < cur + BTRFS_STRIPE_LEN) {
+                       *ret_len = cur + BTRFS_STRIPE_LEN - bytenr;
+                       return 0;
+               }
+       }
+       for (i = 1; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+               u64 cur = btrfs_sb_offset(i);
+
+               /*
+                *      |--reserved--|
+                * |----range-------|
+                * May still need to go through file extent inserts
+                */
+               if (bytenr < cur && bytenr + len >= cur) {
+                       len = min_t(u64, len, cur - bytenr);
+                       break;
+               }
+               /*
+                * |--reserved--|
+                *      |---range---|
+                * Drop out, no need to insert anything
+                */
+               if (bytenr >= cur && bytenr < cur + BTRFS_STRIPE_LEN) {
+                       *ret_len = cur + BTRFS_STRIPE_LEN - bytenr;
+                       return 0;
+               }
+       }
+
        cache = search_cache_extent(used, bytenr);
        if (cache) {
                if (cache->start <= bytenr) {
@@ -1425,7 +1468,7 @@ static int migrate_reserved_ranges(struct btrfs_trans_handle *trans,
        /* second sb(fisrt sb is included in 0~1M) */
        cur_off = btrfs_sb_offset(1);
        cur_len = min(total_bytes, cur_off + BTRFS_STRIPE_LEN) - cur_off;
-       if (cur_off < total_bytes)
+       if (cur_off > total_bytes)
                return ret;
        ret = migrate_one_reserved_range(trans, root, used, inode, fd, ino,
                                         cur_off, cur_len, datacsum);
@@ -1435,7 +1478,7 @@ static int migrate_reserved_ranges(struct btrfs_trans_handle *trans,
        /* Last sb */
        cur_off = btrfs_sb_offset(2);
        cur_len = min(total_bytes, cur_off + BTRFS_STRIPE_LEN) - cur_off;
-       if (cur_off < total_bytes)
+       if (cur_off > total_bytes)
                return ret;
        ret = migrate_one_reserved_range(trans, root, used, inode, fd, ino,
                                         cur_off, cur_len, datacsum);