From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josef Bacik Subject: Re: [PATCH 2/3] Btrfs: make btrfs_truncate_inode_items() more readable Date: Thu, 5 Jan 2012 10:11:43 -0500 Message-ID: <20120105151142.GB1843@localhost.localdomain> References: <4F056029.2080306@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linux Btrfs To: Miao Xie Return-path: In-Reply-To: <4F056029.2080306@cn.fujitsu.com> List-ID: 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 > --- > 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