Introduce new function, check_rollback(), to collect data and check if
we can rollback the image.
The check part is quite straight forward:
Ensure all the file extents, except the ones inside reserved ranges, are
mapped 1:1 on disk.
The ones inside reserved ranges, 0~1M, 1st sb +64K, 2nd sb +64K, can be
mapped to anywhere, as btrfs needs to put super blocks in them.
Such behavir can meet both old convert(one large chunk) and new
convert(only old image file is 1:1 mapped).
Also, the function will read out the data in btrfs reserved ranges for
later rollback usage.
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
convert/main.c | 214 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 214 insertions(+)
diff --git a/convert/main.c b/convert/main.c
index 87c52c1..5b9141b 100644
--- a/convert/main.c
+++ b/convert/main.c
@@ -2781,6 +2781,220 @@ static int record_reloc_data(struct btrfs_fs_info
*fs_info,
return 0;
}
+static int check_image_file_extents(struct btrfs_root *image_root, u64 ino,
+ u64 total_size, char *reloc_ranges[3])
+{
+ struct btrfs_key key;
+ struct btrfs_path path;
+ struct btrfs_fs_info *fs_info = image_root->fs_info;
+ u64 checked_bytes = 0;
+ int ret;
+
+ key.objectid = ino;
+ key.offset = 0;
+ key.type = BTRFS_EXTENT_DATA_KEY;
+
+ btrfs_init_path(&path);
+ ret = btrfs_search_slot(NULL, image_root, &key, &path, 0, 0);
+ /*
+ * It's possible that some fs doesn't store any(including sb)
+ * data into 0~1M range, and NO_HOLES is enabled.
+ *
+ * So only needs to check ret < 0 case
+ */
+ if (ret < 0) {
+ error("failed to iterate file extents at offset 0: %s",
+ strerror(-ret));
+ btrfs_release_path(&path);
+ return ret;
+ }
+
+ /* Loop from the first file extents */
+ while (1) {
+ struct btrfs_file_extent_item *fi;
+ struct extent_buffer *leaf = path.nodes[0];
+ u64 disk_bytenr;
+ u64 file_offset;
+ u64 ram_bytes;
+ u64 extent_offset;
+ int slot = path.slots[0];
+
+ if (slot >= btrfs_header_nritems(leaf))
+ goto next;
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+
+ /*
+ * Iteration is done, exit normally, we have extra check out of
+ * the loop
+ */
+ if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) {
+ ret = 0;
+ break;
+ }
+ file_offset = key.offset;
+ fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+ if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG) {
+ ret = -EINVAL;
+ error(
+ "ino %llu offset %llu doesn't have a regular file extent",
+ ino, file_offset);
+ break;
+ }
+ if (btrfs_file_extent_compression(leaf, fi) ||
+ btrfs_file_extent_encryption(leaf, fi) ||
+ btrfs_file_extent_other_encoding(leaf, fi)) {
+ ret = -EINVAL;
+ error(
+ "ino %llu offset %llu doesn't have a plain file extent",
+ ino, file_offset);
+ break;
+ }
+
+ disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+ ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
+ extent_offset = btrfs_file_extent_offset(leaf, fi);
+
+ checked_bytes += ram_bytes;
+ /* Skip hole */
+ if (disk_bytenr == 0)
+ goto next;
+
+ if (file_offset != disk_bytenr) {
+ /*
+ * Only file extent in btrfs reserved ranges are allow
+ * non-1:1 mapped
+ */
+ if (!is_range_subset_of_reserved_ranges(file_offset,
+ ram_bytes)) {
+ ret = -EINVAL;
+ error(
+ "ino %llu offset %llu file extent should not be relocated",
+ ino, file_offset);
+ break;
+ }
+ }
+ ret = record_reloc_data(fs_info, file_offset,
+ disk_bytenr + extent_offset, ram_bytes,
+ reloc_ranges);
+ if (ret < 0) {
+ error("ino %llu offset %llu failed to read extent data",
+ ino, file_offset);
+ break;
+ }
+next:
+ ret = btrfs_next_item(image_root, &path);
+ if (ret) {
+ if (ret > 0)
+ ret = 0;
+ break;
+ }
+ }
+ btrfs_release_path(&path);
+ /*
+ * For HOLES mode (without NO_HOLES), we must ensure file extents
+ * cover the whole range of the image
+ */
+ if (!ret && !btrfs_fs_incompat(fs_info, NO_HOLES)) {
+ if (checked_bytes != total_size) {
+ ret = -EINVAL;
+ error("inode %llu has some file extents not checked",
+ ino);
+ }
+ }
+ return ret;
+}
+
+/*
+ * Check and record needed blocks for rollback.
+ *
+ * It will record data for superblock and reserved ranges to reloc_ranges[].
+ * So we can rollback the fs after close_ctree().
+ */
+static int check_rollback(struct btrfs_fs_info *fs_info, char *reloc_ranges[3])
+{
+ struct btrfs_root *image_root;
+ struct btrfs_dir_item *dir;
+ struct btrfs_path path;
+ struct btrfs_key key;
+ struct btrfs_inode_item *inode_item;
+ char *image_name = "image";
+ u64 ino;
+ u64 root_dir;
+ u64 total_bytes;
+ int ret;
+
+ btrfs_init_path(&path);
+
+ /*
+ * Search for root backref, or after subvolume delete(orphan),
+ * we can still rollback if the subvolume is just orphan.
+ */
+ key.objectid = CONV_IMAGE_SUBVOL_OBJECTID;
+ key.type = BTRFS_ROOT_BACKREF_KEY;
+ key.offset = BTRFS_FS_TREE_OBJECTID;
+
+ ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, &path, 0, 0);
+ btrfs_release_path(&path);
+ if (ret > 0) {
+ error("unable to convert ext2 image subvolume, is it deleted?");
+ return -ENOENT;
+ } else if (ret < 0) {
+ error("failed to find ext2 image subvolume: %s",
+ strerror(-ret));
+ return ret;
+ }
+
+ /* Search convert subvolume */
+ key.objectid = CONV_IMAGE_SUBVOL_OBJECTID;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ image_root = btrfs_read_fs_root(fs_info, &key);
+ if (IS_ERR(image_root)) {
+ ret = PTR_ERR(image_root);
+ error("failed to open convert image subvolume: %s",
+ strerror(-ret));
+ return ret;
+ }
+
+ /* Search the image file */
+ root_dir = btrfs_root_dirid(&image_root->root_item);
+ dir = btrfs_lookup_dir_item(NULL, image_root, &path, root_dir,
+ image_name, strlen(image_name), 0);
+
+ if (!dir || IS_ERR(dir)) {
+ btrfs_release_path(&path);
+ if (dir)
+ ret = PTR_ERR(dir);
+ else
+ ret = -ENOENT;
+ error("failed to locate file %s: %s", image_name,
+ strerror(-ret));
+ return ret;
+ }
+ btrfs_dir_item_key_to_cpu(path.nodes[0], dir, &key);
+ btrfs_release_path(&path);
+
+ /* Get total size of the original image */
+ ino = key.objectid;
+
+ ret = btrfs_lookup_inode(NULL, image_root, &path, &key, 0);
+ if (ret < 0) {
+ btrfs_release_path(&path);
+ error("unable to find inode %llu: %s", ino, strerror(-ret));
+ return ret;
+ }
+ inode_item = btrfs_item_ptr(path.nodes[0], path.slots[0],
+ struct btrfs_inode_item);
+ total_bytes = btrfs_inode_size(path.nodes[0], inode_item);
+ btrfs_release_path(&path);
+
+ /* Main function to check every file extent of the image file */
+ ret = check_image_file_extents(image_root, ino, total_bytes,
+ reloc_ranges);
+ return ret;
+}
+
static int do_rollback(const char *devname)
{
int fd = -1;
--
2.10.2
--
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