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>

1 files changed, 12 insertions, 9 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 96df1b10cb60..9260d3478aad 100644
--- 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;