Btrfs: Fix for insert_inline_extent to handle offset != 0

This modifies inline extent size calculation, so that
insert_inline_extent can handle the case that parameter 'offset' is
not zero; it also a few codes to zero uninitialized area in inline
extent.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 96df1b10cb608e3a0042e425b25f7f2c66329d7c..9260d3478aadbf6665a8576fe96d416b3e5ebcd1 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -108,7 +108,6 @@ static int insert_inline_extent(struct btrfs_trans_handle *trans,
        key.objectid = inode->i_ino;
        key.offset = offset;
        btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
-       datasize = btrfs_file_extent_calc_inline_size(offset + size);
 
        ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
        if (ret < 0) {
@@ -130,7 +129,7 @@ static int insert_inline_extent(struct btrfs_trans_handle *trans,
        }
        if (ret == 0) {
                u32 found_size;
-               u64 found_start;
+               u64 found_end;
 
                leaf = path->nodes[0];
                ei = btrfs_item_ptr(leaf, path->slots[0],
@@ -144,19 +143,17 @@ static int insert_inline_extent(struct btrfs_trans_handle *trans,
                               offset, inode->i_ino);
                        goto fail;
                }
-               found_start = key.offset;
                found_size = btrfs_file_extent_inline_len(leaf,
                                          btrfs_item_nr(leaf, path->slots[0]));
+               found_end = key.offset + found_size;
 
-               if (found_size < offset + size) {
+               if (found_end < offset + size) {
                        btrfs_release_path(root, path);
                        ret = btrfs_search_slot(trans, root, &key, path,
-                                               offset + size - found_size -
-                                               found_start, 1);
+                                               offset + size - found_end, 1);
                        BUG_ON(ret != 0);
                        ret = btrfs_extend_item(trans, root, path,
-                                               offset + size - found_size -
-                                               found_start);
+                                               offset + size - found_end);
                        if (ret) {
                                err = ret;
                                goto fail;
@@ -165,9 +162,15 @@ static int insert_inline_extent(struct btrfs_trans_handle *trans,
                        ei = btrfs_item_ptr(leaf, path->slots[0],
                                            struct btrfs_file_extent_item);
                }
+               if (found_end < offset) {
+                       ptr = btrfs_file_extent_inline_start(ei) + found_size;
+                       memset_extent_buffer(leaf, 0, ptr, offset - found_end);
+               }
        } else {
 insert:
                btrfs_release_path(root, path);
+               datasize = offset + size - key.offset;
+               datasize = btrfs_file_extent_calc_inline_size(datasize);
                ret = btrfs_insert_empty_item(trans, root, path, &key,
                                              datasize);
                if (ret) {
@@ -181,7 +184,7 @@ insert:
                btrfs_set_file_extent_generation(leaf, ei, trans->transid);
                btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
        }
-       ptr = btrfs_file_extent_inline_start(ei) + offset;
+       ptr = btrfs_file_extent_inline_start(ei) + offset - key.offset;
 
        cur_size = size;
        i = 0;