On Fri, Jun 06, 2014 at 05:05:51AM +0100, Filipe David Borba Manana wrote:
> When cloning into a file, we were correctly replacing the extent
> items in the target range and removing the extent maps. However
> we weren't replacing the extent maps with new ones that point to
> the new extents - as a consequence, an incremental fsync (when the
> inode doesn't have the full sync flag) was a NOOP, since it relies
> on the existence of extent maps in the modified list of the inode's
> extent map tree, which was empty. Therefore add new extent maps to
> reflect the target clone range.
>
> A test case for xfstests follows.
>
> Signed-off-by: Filipe David Borba Manana <fdmanana@xxxxxxxxx>
> ---
> fs/btrfs/ioctl.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 114 insertions(+)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 44dcfd0..1197478 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3043,6 +3043,104 @@ out:
> return ret;
> }
>
> +static void clone_update_extent_map(struct inode *inode,
> + const struct btrfs_trans_handle *trans,
> + const struct btrfs_path *path,
> + const struct btrfs_key *key,
> + struct btrfs_file_extent_item *fi,
> + const u64 hole_offset,
> + const u64 hole_len)
> +{
> + struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
> + struct btrfs_root *root = BTRFS_I(inode)->root;
> + struct extent_buffer *leaf = path->nodes[0];
> + const int slot = path->slots[0];
> + struct extent_map *em;
> + u64 extent_start, extent_end;
> + u64 bytenr;
> + u8 type;
> + int ret;
> +
> + em = alloc_extent_map();
> + if (!em) {
> + set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
> + &BTRFS_I(inode)->runtime_flags);
> + return;
> + }
> +
> + em->bdev = root->fs_info->fs_devices->latest_bdev;
> + if (!fi) {
> + em->start = hole_offset;
> + em->len = hole_len;
> + em->ram_bytes = em->len;
> + em->orig_start = hole_offset;
> + em->block_start = EXTENT_MAP_HOLE;
> + em->block_len = 0;
> + em->orig_block_len = 0;
> + em->compress_type = BTRFS_COMPRESS_NONE;
> + em->generation = trans->transid;
> + goto insert_em;
> + }
> +
> + em->generation = -1;
> + extent_start = key->offset;
> + extent_end = extent_start + btrfs_file_extent_num_bytes(leaf, fi);
> + bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
> + type = btrfs_file_extent_type(leaf, fi);
> +
> + em->start = extent_start;
> + em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
> + em->compress_type = btrfs_file_extent_compression(leaf, fi);
> +
> + if (em->compress_type != BTRFS_COMPRESS_NONE)
> + set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
> +
> + if (type == BTRFS_FILE_EXTENT_INLINE) {
> + em->len = ALIGN(btrfs_file_extent_inline_len(leaf, slot, fi),
> + root->sectorsize);
> + em->orig_block_len = em->len;
> + em->orig_start = em->start;
> + em->block_start = EXTENT_MAP_INLINE;
> + em->block_len = (u64)-1;
> + goto insert_em;
> + }
> +
> + em->len = extent_end - extent_start;
> + em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
> + em->orig_start = extent_start - btrfs_file_extent_offset(leaf, fi);
> + if (bytenr == 0)
> + em->block_start = EXTENT_MAP_HOLE;
> + else
> + em->block_start = bytenr;
> +
> + if (em->compress_type == BTRFS_COMPRESS_NONE) {
> + em->block_start += btrfs_file_extent_offset(leaf, fi);
> + em->block_len = em->len;
> + } else {
> + em->block_len = em->orig_block_len;
> + }
> +
> + if (type == BTRFS_FILE_EXTENT_PREALLOC)
> + set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
> +
> +insert_em:
> + while (1) {
> + write_lock(&em_tree->lock);
> + ret = add_extent_mapping(em_tree, em, 1);
> + write_unlock(&em_tree->lock);
> + if (ret != -EEXIST) {
> + free_extent_map(em);
> + break;
> + }
> + btrfs_drop_extent_cache(inode, em->start,
> + em->start + em->len - 1, 0);
> + }
> +
> + if (unlikely(ret))
> + set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
> + &BTRFS_I(inode)->runtime_flags);
> +}
> +
Similar code to btrfs_get_extent(), can we use that instead?
-liubo
> /**
> * btrfs_clone() - clone a range from inode file to another
> *
> @@ -3361,8 +3459,19 @@ process_slot:
> btrfs_item_ptr_offset(leaf, slot),
> size);
> inode_add_bytes(inode, datal);
> + extent = btrfs_item_ptr(leaf, slot,
> + struct btrfs_file_extent_item);
> }
>
> + /* If we have an implicit hole (NO_HOLES feature). */
> + if (drop_start < new_key.offset)
> + clone_update_extent_map(inode, trans,
> + path, NULL, NULL, drop_start,
> + new_key.offset - drop_start);
> +
> + clone_update_extent_map(inode, trans, path,
> + &new_key, extent, 0, 0);
> +
> btrfs_mark_buffer_dirty(leaf);
> btrfs_release_path(path);
>
> @@ -3406,6 +3515,11 @@ process_slot:
> }
> ret = clone_finish_inode_update(trans, inode, destoff + len,
> destoff, olen);
> + if (ret)
> + goto out;
> + clone_update_extent_map(inode, trans,
> + path, NULL, NULL, last_dest_end,
> + destoff + len - last_dest_end);
> }
>
> out:
> --
> 1.9.1
>
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