Btrfs: don't use ram_bytes for uncompressed inline items

commit 514ac8ad upstream.

If we truncate an uncompressed inline item, ram_bytes isn't updated to reflect
the new size.  The fixe uses the size directly from the item header when
reading uncompressed inlines, and also fixes truncate to update the
size as it goes.
Reported-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
[bwh: Backported to 3.2:
 - Don't use btrfs_map_token API
 - There are fewer callers of btrfs_file_extent_inline_len() to change
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/btrfs/ctree.h

@@ -2174,15 +2174,6 @@ BTRFS_SETGET_FUNCS(file_extent_encryption, struct btrfs_file_extent_item,
 BTRFS_SETGET_FUNCS(file_extent_other_encoding, struct btrfs_file_extent_item,
 		   other_encoding, 16);
 
-/* this returns the number of file bytes represented by the inline item.
- * If an item is compressed, this is the uncompressed size
- */
-static inline u32 btrfs_file_extent_inline_len(struct extent_buffer *eb,
-					       struct btrfs_file_extent_item *e)
-{
-	return btrfs_file_extent_ram_bytes(eb, e);
-}
-
 /*
  * this returns the number of bytes used by the item on disk, minus the
  * size of any extent headers.  If a file is compressed on disk, this is
@@ -2196,6 +2187,29 @@ static inline u32 btrfs_file_extent_inline_item_len(struct extent_buffer *eb,
 	return btrfs_item_size(eb, e) - offset;
 }
 
+/* this returns the number of file bytes represented by the inline item.
+ * If an item is compressed, this is the uncompressed size
+ */
+static inline u32 btrfs_file_extent_inline_len(struct extent_buffer *eb,
+					       int slot,
+					       struct btrfs_file_extent_item *fi)
+{
+	/*
+	 * return the space used on disk if this item isn't
+	 * compressed or encoded
+	 */
+	if (btrfs_file_extent_compression(eb, fi) == 0 &&
+	    btrfs_file_extent_encryption(eb, fi) == 0 &&
+	    btrfs_file_extent_other_encoding(eb, fi) == 0) {
+		return btrfs_file_extent_inline_item_len(eb,
+							 btrfs_item_nr(eb, slot));
+	}
+
+	/* otherwise use the ram bytes field */
+	return btrfs_file_extent_ram_bytes(eb, fi);
+}
+
+
 static inline struct btrfs_root *btrfs_sb(struct super_block *sb)
 {
 	return sb->s_fs_info;

fs/btrfs/file.c

@@ -622,7 +622,8 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
 				btrfs_file_extent_num_bytes(leaf, fi);
 		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 			extent_end = key.offset +
-				btrfs_file_extent_inline_len(leaf, fi);
+				btrfs_file_extent_inline_len(leaf,
+						     path->slots[0], fi);
 		} else {
 			WARN_ON(1);
 			extent_end = search_start;

fs/btrfs/inode.c

@@ -1178,7 +1178,8 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 			nocow = 1;
 		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 			extent_end = found_key.offset +
-				btrfs_file_extent_inline_len(leaf, fi);
+				btrfs_file_extent_inline_len(leaf,
+						     path->slots[0], fi);
 			extent_end = ALIGN(extent_end, root->sectorsize);
 		} else {
 			BUG_ON(1);
@@ -3095,7 +3096,7 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 				    btrfs_file_extent_num_bytes(leaf, fi);
 			} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 				item_end += btrfs_file_extent_inline_len(leaf,
-									 fi);
+							 path->slots[0], fi);
 			}
 			item_end--;
 		}
@@ -3161,6 +3162,12 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 					inode_sub_bytes(inode, item_end + 1 -
 							new_size);
 				}
+
+				/*
+				 * update the ram bytes to properly reflect
+				 * the new size of our item
+				 */
+				btrfs_set_file_extent_ram_bytes(leaf, fi, size);
 				size =
 				    btrfs_file_extent_calc_inline_size(size);
 				ret = btrfs_truncate_item(trans, root, path,
@@ -5036,7 +5043,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 		       btrfs_file_extent_num_bytes(leaf, item);
 	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 		size_t size;
-		size = btrfs_file_extent_inline_len(leaf, item);
+		size = btrfs_file_extent_inline_len(leaf, path->slots[0], item);
 		extent_end = (extent_start + size + root->sectorsize - 1) &
 			~((u64)root->sectorsize - 1);
 	}
@@ -5103,7 +5110,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 			goto out;
 		}
 
-		size = btrfs_file_extent_inline_len(leaf, item);
+		size = btrfs_file_extent_inline_len(leaf, path->slots[0], item);
 		extent_offset = page_offset(page) + pg_offset - extent_start;
 		copy_size = min_t(u64, PAGE_CACHE_SIZE - pg_offset,
 				size - extent_offset);

fs/btrfs/print-tree.c

@@ -240,7 +240,7 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 			    BTRFS_FILE_EXTENT_INLINE) {
 				printk(KERN_INFO "\t\tinline extent data "
 				       "size %u\n",
-				       btrfs_file_extent_inline_len(l, fi));
+				       btrfs_file_extent_inline_len(l, i, fi));
 				break;
 			}
 			printk(KERN_INFO "\t\textent data disk bytenr %llu "

fs/btrfs/tree-log.c

@@ -537,7 +537,7 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
 		if (btrfs_file_extent_disk_bytenr(eb, item) == 0)
 			nbytes = 0;
 	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
-		size = btrfs_file_extent_inline_len(eb, item);
+		size = btrfs_file_extent_inline_len(eb, slot, item);
 		nbytes = btrfs_file_extent_ram_bytes(eb, item);
 		extent_end = (start + size + mask) & ~mask;
 	} else {