ext4: ext4_inline_data_fiemap should respect callers argument

Currently ext4_inline_data_fiemap ignores requested arguments (start
and len) which may lead endless loop if start != 0.  Also fix incorrect
extent length determination.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -2634,7 +2634,7 @@ extern struct buffer_head *ext4_get_first_inline_block(struct inode *inode,
 					int *retval);
 extern int ext4_inline_data_fiemap(struct inode *inode,
 				   struct fiemap_extent_info *fieinfo,
-				   int *has_inline);
+				   int *has_inline, __u64 start, __u64 len);
 extern int ext4_try_to_evict_inline_data(handle_t *handle,
 					 struct inode *inode,
 					 int needed);

fs/ext4/extents.c

@@ -5151,7 +5151,8 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	if (ext4_has_inline_data(inode)) {
 		int has_inline = 1;
 
-		error = ext4_inline_data_fiemap(inode, fieinfo, &has_inline);
+		error = ext4_inline_data_fiemap(inode, fieinfo, &has_inline,
+						start, len);
 
 		if (has_inline)
 			return error;

fs/ext4/inline.c

@@ -1808,11 +1808,12 @@ int ext4_destroy_inline_data(handle_t *handle, struct inode *inode)
 
 int ext4_inline_data_fiemap(struct inode *inode,
 			    struct fiemap_extent_info *fieinfo,
-			    int *has_inline)
+			    int *has_inline, __u64 start, __u64 len)
 {
 	__u64 physical = 0;
-	__u64 length;
-	__u32 flags = FIEMAP_EXTENT_DATA_INLINE | FIEMAP_EXTENT_LAST;
+	__u64 inline_len;
+	__u32 flags = FIEMAP_EXTENT_DATA_INLINE | FIEMAP_EXTENT_NOT_ALIGNED |
+		FIEMAP_EXTENT_LAST;
 	int error = 0;
 	struct ext4_iloc iloc;
 
@@ -1821,6 +1822,13 @@ int ext4_inline_data_fiemap(struct inode *inode,
 		*has_inline = 0;
 		goto out;
 	}
+	inline_len = min_t(size_t, ext4_get_inline_size(inode),
+			   i_size_read(inode));
+	if (start >= inline_len)
+		goto out;
+	if (start + len < inline_len)
+		inline_len = start + len;
+	inline_len -= start;
 
 	error = ext4_get_inode_loc(inode, &iloc);
 	if (error)
@@ -1829,11 +1837,10 @@ int ext4_inline_data_fiemap(struct inode *inode,
 	physical = (__u64)iloc.bh->b_blocknr << inode->i_sb->s_blocksize_bits;
 	physical += (char *)ext4_raw_inode(&iloc) - iloc.bh->b_data;
 	physical += offsetof(struct ext4_inode, i_block);
-	length = i_size_read(inode);
 
 	if (physical)
-		error = fiemap_fill_next_extent(fieinfo, 0, physical,
-						length, flags);
+		error = fiemap_fill_next_extent(fieinfo, start, physical,
+						inline_len, flags);
 	brelse(iloc.bh);
 out:
 	up_read(&EXT4_I(inode)->xattr_sem);