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@@ -15,18 +15,34 @@
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#define BTRFS_SUPER_INFO_SIZE 4096
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-static int btrfs_newest_root_backup(struct btrfs_super_block *sb)
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+/*
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+ * checks if a valid root backup is present.
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+ * considers the case when all root backups empty valid.
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+ * returns -1 in case of invalid root backup and 0 for valid.
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+ */
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+static int btrfs_check_super_roots(struct btrfs_super_block *sb)
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{
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struct btrfs_root_backup *root_backup;
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int i, newest = -1;
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+ int num_empty = 0;
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for (i = 0; i < BTRFS_NUM_BACKUP_ROOTS; ++i) {
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root_backup = sb->super_roots + i;
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+
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+ if (root_backup->tree_root == 0 && root_backup->tree_root_gen == 0)
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+ num_empty++;
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+
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if (root_backup->tree_root_gen == sb->generation)
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newest = i;
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}
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- return newest;
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+ if (num_empty == BTRFS_NUM_BACKUP_ROOTS) {
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+ return 0;
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+ } else if (newest >= 0) {
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+ return 0;
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+ }
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+
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+ return -1;
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}
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static inline int is_power_of_2(u64 x)
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@@ -166,7 +182,7 @@ int btrfs_read_superblock(void)
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char raw_sb[BTRFS_SUPER_INFO_SIZE];
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struct btrfs_super_block *sb = (struct btrfs_super_block *) raw_sb;
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u64 dev_total_bytes;
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- int i, root_backup_idx;
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+ int i;
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dev_total_bytes = (u64) btrfs_part_info->size * btrfs_part_info->blksz;
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@@ -211,17 +227,15 @@ int btrfs_read_superblock(void)
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return -1;
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}
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- root_backup_idx = btrfs_newest_root_backup(&btrfs_info.sb);
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- if (root_backup_idx < 0) {
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+ if (btrfs_check_super_roots(&btrfs_info.sb)) {
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printf("%s: No valid root_backup found!\n", __func__);
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return -1;
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}
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- btrfs_info.root_backup = btrfs_info.sb.super_roots + root_backup_idx;
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- if (btrfs_info.root_backup->num_devices != 1) {
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+ if (btrfs_info.sb.num_devices != 1) {
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printf("%s: Unsupported number of devices (%lli). This driver "
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"only supports filesystem on one device.\n", __func__,
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- btrfs_info.root_backup->num_devices);
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+ btrfs_info.sb.num_devices);
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return -1;
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}
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