return 0;
}
+/*
+ * helper function for csum removal, this expects the
+ * key to describe the csum pointed to by the path, and it expects
+ * the csum to overlap the range [bytenr, len]
+ *
+ * The csum should not be entirely contained in the range and the
+ * range should not be entirely contained in the csum.
+ *
+ * This calls btrfs_truncate_item with the correct args based on the
+ * overlap, and fixes up the key as required.
+ */
+static noinline int truncate_one_csum(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct btrfs_path *path,
+ struct btrfs_key *key,
+ u64 bytenr, u64 len)
+{
+ struct extent_buffer *leaf;
+ u16 csum_size =
+ btrfs_super_csum_size(&root->fs_info->super_copy);
+ u64 csum_end;
+ u64 end_byte = bytenr + len;
+ u32 blocksize_bits = root->fs_info->sb->s_blocksize_bits;
+ int ret;
+
+ leaf = path->nodes[0];
+ csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
+ csum_end <<= root->fs_info->sb->s_blocksize_bits;
+ csum_end += key->offset;
+
+ if (key->offset < bytenr && csum_end <= end_byte) {
+ /*
+ * [ bytenr - len ]
+ * [ ]
+ * [csum ]
+ * A simple truncate off the end of the item
+ */
+ u32 new_size = (bytenr - key->offset) >> blocksize_bits;
+ new_size *= csum_size;
+ ret = btrfs_truncate_item(trans, root, path, new_size, 1);
+ BUG_ON(ret);
+ } else if (key->offset >= bytenr && csum_end > end_byte &&
+ end_byte > key->offset) {
+ /*
+ * [ bytenr - len ]
+ * [ ]
+ * [csum ]
+ * we need to truncate from the beginning of the csum
+ */
+ u32 new_size = (csum_end - end_byte) >> blocksize_bits;
+ new_size *= csum_size;
+
+ ret = btrfs_truncate_item(trans, root, path, new_size, 0);
+ BUG_ON(ret);
+
+ key->offset = end_byte;
+ ret = btrfs_set_item_key_safe(trans, root, path, key);
+ BUG_ON(ret);
+ } else {
+ BUG();
+ }
+ return 0;
+}
+
+/*
+ * deletes the csum items from the csum tree for a given
+ * range of bytes.
+ */
+int btrfs_del_csums(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, u64 bytenr, u64 len)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ u64 end_byte = bytenr + len;
+ u64 csum_end;
+ struct extent_buffer *leaf;
+ int ret;
+ u16 csum_size =
+ btrfs_super_csum_size(&root->fs_info->super_copy);
+ int blocksize_bits = root->fs_info->sb->s_blocksize_bits;
+
+ root = root->fs_info->csum_root;
+
+ path = btrfs_alloc_path();
+
+ while(1) {
+ key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
+ key.offset = end_byte - 1;
+ key.type = BTRFS_EXTENT_CSUM_KEY;
+
+ ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+ if (ret > 0) {
+ if (path->slots[0] == 0)
+ goto out;
+ path->slots[0]--;
+ }
+ leaf = path->nodes[0];
+ btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+ if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
+ key.type != BTRFS_EXTENT_CSUM_KEY) {
+ break;
+ }
+
+ if (key.offset >= end_byte)
+ break;
+
+ csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
+ csum_end <<= blocksize_bits;
+ csum_end += key.offset;
+
+ /* this csum ends before we start, we're done */
+ if (csum_end <= bytenr)
+ break;
+
+ /* delete the entire item, it is inside our range */
+ if (key.offset >= bytenr && csum_end <= end_byte) {
+ ret = btrfs_del_item(trans, root, path);
+ BUG_ON(ret);
+ } else if (key.offset < bytenr && csum_end > end_byte) {
+ unsigned long offset;
+ unsigned long shift_len;
+ unsigned long item_offset;
+ /*
+ * [ bytenr - len ]
+ * [csum ]
+ *
+ * Our bytes are in the middle of the csum,
+ * we need to split this item and insert a new one.
+ *
+ * But we can't drop the path because the
+ * csum could change, get removed, extended etc.
+ *
+ * The trick here is the max size of a csum item leaves
+ * enough room in the tree block for a single
+ * item header. So, we split the item in place,
+ * adding a new header pointing to the existing
+ * bytes. Then we loop around again and we have
+ * a nicely formed csum item that we can neatly
+ * truncate.
+ */
+ offset = (bytenr - key.offset) >> blocksize_bits;
+ offset *= csum_size;
+
+ shift_len = (len >> blocksize_bits) * csum_size;
+
+ item_offset = btrfs_item_ptr_offset(leaf,
+ path->slots[0]);
+
+ memset_extent_buffer(leaf, 0, item_offset + offset,
+ shift_len);
+ key.offset = bytenr;
+
+ /*
+ * btrfs_split_item returns -EAGAIN when the
+ * item changed size or key
+ */
+ ret = btrfs_split_item(trans, root, path, &key, offset);
+ BUG_ON(ret && ret != -EAGAIN);
+
+ key.offset = end_byte - 1;
+ } else {
+ ret = truncate_one_csum(trans, root, path,
+ &key, bytenr, len);
+ BUG_ON(ret);
+ }
+ btrfs_release_path(root, path);
+ }
+out:
+ btrfs_free_path(path);
+ return 0;
+}
+
int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_ordered_sum *sums)
csum_size, 1);
if (ret < 0)
goto fail_unlock;
- if (ret == 0) {
- BUG();
- }
- if (path->slots[0] == 0) {
- goto insert;
+
+ if (ret > 0) {
+ if (path->slots[0] == 0)
+ goto insert;
+ path->slots[0]--;
}
- path->slots[0]--;
+
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
csum_offset = (bytenr - found_key.offset) >>
root->fs_info->sb->s_blocksize_bits;
+
if (btrfs_key_type(&found_key) != BTRFS_EXTENT_CSUM_KEY ||
found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
csum_offset >= MAX_CSUM_ITEMS(root, csum_size)) {
goto insert;
}
+
if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
csum_size) {
u32 diff = (csum_offset + 1) * csum_size;
+
+ /*
+ * is the item big enough already? we dropped our lock
+ * before and need to recheck
+ */
+ if (diff < btrfs_item_size_nr(leaf, path->slots[0]))
+ goto csum;
+
diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
- if (diff != csum_size)
+ if (diff != csum_size) {
goto insert;
+ }
+
ret = btrfs_extend_item(trans, root, path, diff);
BUG_ON(ret);
goto csum;
fail_unlock:
goto out;
}
-
-int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
- struct btrfs_root *root, struct btrfs_path *path,
- u64 isize)
-{
- struct btrfs_key key;
- struct extent_buffer *leaf = path->nodes[0];
- int slot = path->slots[0];
- int ret;
- u32 new_item_size;
- u64 new_item_span;
- u64 blocks;
-
- btrfs_item_key_to_cpu(leaf, &key, slot);
- if (isize <= key.offset)
- return 0;
- new_item_span = isize - key.offset;
- blocks = (new_item_span + root->sectorsize - 1) >>
- root->fs_info->sb->s_blocksize_bits;
- new_item_size = blocks *
- btrfs_super_csum_size(&root->fs_info->super_copy);
- if (new_item_size >= btrfs_item_size_nr(leaf, slot))
- return 0;
- ret = btrfs_truncate_item(trans, root, path, new_item_size, 1);
- BUG_ON(ret);
- return ret;
-}
projects / linux-2.6-block.git / blobdiff