Miao Xie
2012-Jan-10 03:58 UTC
[PATCH V2 2/3] Btrfs: make btrfs_truncate_inode_items() more readable
As the title said, this patch just make the functions of the truncation
more readable.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
---
Changes v1 -> v2:
- move return sentence out of if...else..., make the logic of the code more
clear.
---
fs/btrfs/inode.c | 292 ++++++++++++++++++++++++++++++------------------------
1 files changed, 162 insertions(+), 130 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 85e2312..4d1d4c4 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2977,10 +2977,145 @@ 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);
+
+ ret = 0;
+ } 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);
+
+ 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 +3124,21 @@ 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 +3146,7 @@ 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 +3165,11 @@ 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 +3178,8 @@ 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 +3189,31 @@ 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) {
--
1.7.6.5
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