btrfs-progs: update btrfs_read_sys_array to match kernel implementation

There are some sanity checks missing on both sides, kernel/userspace.
Preparation to port the missing changes.

Sync code with parent of kernel commit
1ffb22cf8c322bbfea6b35fe23d025841b49fede ("btrfs: cleanup, rename a few
variables in btrfs_read_sys_array")

This effectively reverts progs commit
be96777126d283773e4397278a5662d90676ab88 ("btrfs-progs: Cleanup unneeded
extra variant in btrfs_read_sys_array") so we can apply more of the
kernel patches.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/volumes.c b/volumes.c
index 4e683bb..01cfafe 100644 (file)
--- a/volumes.c
+++ b/volumes.c
@@ -1795,12 +1795,14 @@ int btrfs_read_sys_array(struct btrfs_root *root)
        struct extent_buffer *sb;
        struct btrfs_disk_key *disk_key;
        struct btrfs_chunk *chunk;
-       struct btrfs_key key;
-       u32 num_stripes;
-       u32 len = 0;
        u8 *ptr;
-       u8 *array_end;
+       unsigned long sb_ptr;
        int ret = 0;
+       u32 num_stripes;
+       u32 array_size;
+       u32 len = 0;
+       u32 cur;
+       struct btrfs_key key;
 
        sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
                                          BTRFS_SUPER_INFO_SIZE);
@@ -1808,25 +1810,22 @@ int btrfs_read_sys_array(struct btrfs_root *root)
                return -ENOMEM;
        btrfs_set_buffer_uptodate(sb);
        write_extent_buffer(sb, super_copy, 0, sizeof(*super_copy));
-       array_end = ((u8 *)super_copy->sys_chunk_array) +
-                   btrfs_super_sys_array_size(super_copy);
+       array_size = btrfs_super_sys_array_size(super_copy);
 
-       /*
-        * we do this loop twice, once for the device items and
-        * once for all of the chunks.  This way there are device
-        * structs filled in for every chunk
-        */
        ptr = super_copy->sys_chunk_array;
+       sb_ptr = offsetof(struct btrfs_super_block, sys_chunk_array);
+       cur = 0;
 
-       while (ptr < array_end) {
+       while (cur < array_size) {
                disk_key = (struct btrfs_disk_key *)ptr;
                btrfs_disk_key_to_cpu(&key, disk_key);
 
-               len = sizeof(*disk_key);
-               ptr += len;
+               len = sizeof(*disk_key); ptr += len;
+               sb_ptr += len;
+               cur += len;
 
                if (key.type == BTRFS_CHUNK_ITEM_KEY) {
-                       chunk = (struct btrfs_chunk *)(ptr - (u8 *)super_copy);
+                       chunk = (struct btrfs_chunk *)sb_ptr;
                        ret = read_one_chunk(root, &key, sb, chunk, -1);
                        if (ret)
                                break;
@@ -1836,6 +1835,8 @@ int btrfs_read_sys_array(struct btrfs_root *root)
                        BUG();
                }
                ptr += len;
+               sb_ptr += len;
+               cur += len;
        }
        free_extent_buffer(sb);
        return ret;