On Thu, Jan 05, 2012 at 04:32:41PM +0800, Miao Xie wrote:
> As the title said, this patch just make the functions of the truncation
> more readable.
>
> Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/inode.c | 289 ++++++++++++++++++++++++++++++------------------------
> 1 files changed, 159 insertions(+), 130 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 85e2312..df6060f 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -2977,10 +2977,142 @@ out:
> return err;
> }
>
> +static int btrfs_release_and_test_inline_data_extent(
> + struct btrfs_root *root,
> + struct inode *inode,
> + struct extent_buffer *leaf,
> + struct btrfs_file_extent_item *fi,
> + u64 offset,
> + u64 new_size)
> +{
> + u64 item_end;
> +
> + item_end = offset + btrfs_file_extent_inline_len(leaf, fi) - 1;
> +
> + if (item_end < new_size)
> + return 0;
> +
> + /*
> + * Truncate inline items is special, we have done it by
> + * btrfs_truncate_page();
> + */
> + if (offset < new_size)
> + return 0;
> +
> + if (root->ref_cows)
> + inode_sub_bytes(inode, item_end + 1 - offset);
> +
> + return 1;
> +}
> +
> /*
> - * this can truncate away extent items, csum items and directory items.
> - * It starts at a high offset and removes keys until it can't find
> - * any higher than new_size
> + * If this function return 1, it means this item can be dropped directly.
> + * If 0 is returned, the item can not be dropped.
> + */
> +static int btrfs_release_and_test_data_extent(struct btrfs_trans_handle *trans,
> + struct btrfs_root *root,
> + struct btrfs_path *path,
> + struct inode *inode,
> + u64 offset,
> + u64 new_size)
> +{
> + struct extent_buffer *leaf;
> + struct btrfs_file_extent_item *fi;
> + u64 extent_start;
> + u64 extent_offset;
> + u64 item_end;
> + u64 ino = btrfs_ino(inode);
> + u64 orig_nbytes;
> + u64 new_nbytes;
> + int extent_type;
> + int ret;
> +
> + leaf = path->nodes[0];
> + fi = btrfs_item_ptr(leaf, path->slots[0],
> + struct btrfs_file_extent_item);
> +
> + extent_type = btrfs_file_extent_type(leaf, fi);
> + if (extent_type == BTRFS_FILE_EXTENT_INLINE)
> + return btrfs_release_and_test_inline_data_extent(root, inode,
> + leaf, fi,
> + offset,
> + new_size);
> +
> + item_end = offset + btrfs_file_extent_num_bytes(leaf, fi) - 1;
> +
> + /*
> + * If the new size is beyond the end of the extent:
> + * +--------------------------+
> + * | |
> + * +--------------------------+
> + * ^ new size
> + * so the extent should not be dropped or truncated.
> + */
> + if (item_end < new_size)
> + return 0;
> +
> + extent_start = btrfs_file_extent_disk_bytenr(leaf, fi);
> + if (offset < new_size) {
> + /*
> + * If the new size is in the extent:
> + * +--------------------------+
> + * | |
> + * +--------------------------+
> + * ^ new size
> + * so this extent should be truncated, not be dropped directly.
> + */
> + orig_nbytes = btrfs_file_extent_num_bytes(leaf, fi);
> + new_nbytes = round_up(new_size - offset, root->sectorsize);
> +
> + btrfs_set_file_extent_num_bytes(leaf, fi, new_nbytes);
> +
> + if (extent_start != 0 && root->ref_cows)
> + inode_sub_bytes(inode, orig_nbytes - new_nbytes);
> +
> + btrfs_mark_buffer_dirty(leaf);
> + return 0;
Use ret = 0 here, and then further down...
> + } else {
> + /*
> + * If the new size is in the font of the extent:
> + * +--------------------------+
> + * | |
> + * +--------------------------+
> + * ^ new size
> + * so this extent should be dropped.
> + */
> +
> + /*
> + * It is a dummy extent, or it is in log tree, we needn't do
> + * anything, just drop it.
> + */
> + if (extent_start == 0 ||
> + !(root->ref_cows || root == root->fs_info->tree_root))
> + return 1;
> +
> + /* If this file is not a free space management file... */
> + /* FIXME blocksize != 4096 */
> + if (root != root->fs_info->tree_root) {
> + orig_nbytes = btrfs_file_extent_num_bytes(leaf, fi);
> + inode_sub_bytes(inode, orig_nbytes);
> + }
> +
> + orig_nbytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
> + extent_offset = offset - btrfs_file_extent_offset(leaf, fi);
> + btrfs_set_path_blocking(path);
> + ret = btrfs_free_extent(trans, root, extent_start,
> + orig_nbytes, 0,
> + btrfs_header_owner(leaf),
> + ino, extent_offset);
> + BUG_ON(ret);
> + btrfs_clear_path_blocking(path, NULL, 0);
> +
> + return 1;
ret = 1
> + }
return ret;
> +}
> +
> +/*
> + * this can truncate away extent items, directory items. It starts at a high
> + * offset and removes keys until it can't find any higher than new_size.
> *
> * csum items that cross the new i_size are truncated to the new size
> * as well.
> @@ -2989,29 +3121,21 @@ out:
> * will kill all the items on this inode, including the INODE_ITEM_KEY.
> */
> int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
> - struct btrfs_root *root,
> - struct inode *inode,
> - u64 new_size, u32 min_type)
> + struct btrfs_root *root,
> + struct inode *inode,
> + u64 new_size, u32 min_type)
> {
> struct btrfs_path *path;
> struct extent_buffer *leaf;
> - struct btrfs_file_extent_item *fi;
> struct btrfs_key key;
> struct btrfs_key found_key;
> - u64 extent_start = 0;
> - u64 extent_num_bytes = 0;
> - u64 extent_offset = 0;
> - u64 item_end = 0;
> u64 mask = root->sectorsize - 1;
> - u32 found_type = (u8)-1;
> - int found_extent;
> - int del_item;
> + u64 ino = btrfs_ino(inode);
> + u32 found_type;
> int pending_del_nr = 0;
> int pending_del_slot = 0;
> - int extent_type = -1;
> int ret;
> int err = 0;
> - u64 ino = btrfs_ino(inode);
>
> BUG_ON(new_size > 0 && min_type != BTRFS_EXTENT_DATA_KEY);
>
> @@ -3019,6 +3143,7 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
> if (!path)
> return -ENOMEM;
> path->reada = -1;
> + path->leave_spinning = 1;
>
> if (root->ref_cows || root == root->fs_info->tree_root)
> btrfs_drop_extent_cache(inode, new_size & (~mask), (u64)-1, 0);
> @@ -3037,14 +3162,11 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
> key.type = (u8)-1;
>
> search_again:
> - path->leave_spinning = 1;
> ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
> if (ret < 0) {
> err = ret;
> goto out;
> - }
> -
> - if (ret > 0) {
> + } else if (ret > 0) {
> /* there are no items in the tree for us to truncate, we're
> * done
> */
> @@ -3053,9 +3175,8 @@ search_again:
> path->slots[0]--;
> }
>
> + leaf = path->nodes[0];
> while (1) {
> - fi = NULL;
> - leaf = path->nodes[0];
> btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
> found_type = btrfs_key_type(&found_key);
>
> @@ -3065,123 +3186,31 @@ search_again:
> if (found_type < min_type)
> break;
>
> - item_end = found_key.offset;
> if (found_type == BTRFS_EXTENT_DATA_KEY) {
> - fi = btrfs_item_ptr(leaf, path->slots[0],
> - struct btrfs_file_extent_item);
> - extent_type = btrfs_file_extent_type(leaf, fi);
> - if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
> - item_end +=
> - btrfs_file_extent_num_bytes(leaf, fi);
> - } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
> - item_end += btrfs_file_extent_inline_len(leaf,
> - fi);
> - }
> - item_end--;
> - }
> - if (found_type > min_type) {
> - del_item = 1;
> - } else {
> - if (item_end < new_size)
> + ret = btrfs_release_and_test_data_extent(trans, root,
> + path, inode, found_key.offset,
> + new_size);
> + if (!ret)
> break;
> - if (found_key.offset >= new_size)
> - del_item = 1;
> - else
> - del_item = 0;
> }
> - found_extent = 0;
> - /* FIXME, shrink the extent if the ref count is only 1 */
> - if (found_type != BTRFS_EXTENT_DATA_KEY)
> - goto delete;
> -
> - if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
> - u64 num_dec;
> - extent_start = btrfs_file_extent_disk_bytenr(leaf, fi);
> - if (!del_item) {
> - u64 orig_num_bytes =
> - btrfs_file_extent_num_bytes(leaf, fi);
> - extent_num_bytes = new_size -
> - found_key.offset + root->sectorsize - 1;
> - extent_num_bytes = extent_num_bytes &
> - ~((u64)root->sectorsize - 1);
> - btrfs_set_file_extent_num_bytes(leaf, fi,
> - extent_num_bytes);
> - num_dec = (orig_num_bytes -
> - extent_num_bytes);
> - if (root->ref_cows && extent_start != 0)
> - inode_sub_bytes(inode, num_dec);
> - btrfs_mark_buffer_dirty(leaf);
> - } else {
> - extent_num_bytes =
> - btrfs_file_extent_disk_num_bytes(leaf,
> - fi);
> - extent_offset = found_key.offset -
> - btrfs_file_extent_offset(leaf, fi);
> -
> - /* FIXME blocksize != 4096 */
> - num_dec = btrfs_file_extent_num_bytes(leaf, fi);
> - if (extent_start != 0) {
> - found_extent = 1;
> - if (root->ref_cows)
> - inode_sub_bytes(inode, num_dec);
> - }
> - }
> - } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
> - /*
> - * we can't truncate inline items that have had
> - * special encodings
> - */
> - if (!del_item &&
> - btrfs_file_extent_compression(leaf, fi) == 0 &&
> - btrfs_file_extent_encryption(leaf, fi) == 0 &&
> - btrfs_file_extent_other_encoding(leaf, fi) == 0) {
> - u32 size = new_size - found_key.offset;
> -
> - if (root->ref_cows) {
> - inode_sub_bytes(inode, item_end + 1 -
> - new_size);
> - }
> - size =
> - btrfs_file_extent_calc_inline_size(size);
> - ret = btrfs_truncate_item(trans, root, path,
> - size, 1);
> - } else if (root->ref_cows) {
> - inode_sub_bytes(inode, item_end + 1 -
> - found_key.offset);
> - }
> - }
> -delete:
> - if (del_item) {
> - if (!pending_del_nr) {
> - /* no pending yet, add ourselves */
> - pending_del_slot = path->slots[0];
> - pending_del_nr = 1;
> - } else if (pending_del_nr &&
> - path->slots[0] + 1 == pending_del_slot) {
> - /* hop on the pending chunk */
> - pending_del_nr++;
> - pending_del_slot = path->slots[0];
> - } else {
> - BUG();
> - }
> +
> + if (!pending_del_nr) {
> + /* no pending yet, add ourselves */
> + pending_del_slot = path->slots[0];
> + pending_del_nr = 1;
> + } else if (pending_del_nr &&
> + path->slots[0] + 1 == pending_del_slot) {
> + /* hop on the pending chunk */
> + pending_del_nr++;
> + pending_del_slot = path->slots[0];
> } else {
> - break;
> - }
> - if (found_extent && (root->ref_cows ||
> - root == root->fs_info->tree_root)) {
> - btrfs_set_path_blocking(path);
> - ret = btrfs_free_extent(trans, root, extent_start,
> - extent_num_bytes, 0,
> - btrfs_header_owner(leaf),
> - ino, extent_offset);
> - BUG_ON(ret);
> + BUG();
> }
>
> if (found_type == BTRFS_INODE_ITEM_KEY)
> break;
>
> - if (path->slots[0] == 0 ||
> - path->slots[0] != pending_del_slot) {
> + if (path->slots[0] == 0) {
> if (root->ref_cows &&
> BTRFS_I(inode)->location.objectid !=
> BTRFS_FREE_INO_OBJECTID) {
Looks good. Thanks,
Josef
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