[PATCH 3.16 80/99] ext4: ext4_inline_data_fiemap should respect callers argument

[Ben Hutchings <ben@decadent.org.uk>]

3.16.65-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dmitry Monakhov <dmonakhov@openvz.org>

commit d952d69e268f833c85c0bafee9f67f9dba85044b upstream.

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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/ext4/ext4.h    |  2 +-
 fs/ext4/extents.c |  3 ++-
 fs/ext4/inline.c  | 19 +++++++++++++------
 3 files changed, 16 insertions(+), 8 deletions(-)

--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2712,7 +2712,7 @@ extern struct buffer_head *ext4_get_firs
 					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 void ext4_inline_data_truncate(struct inode *inode, int *has_inline);
 
 extern int ext4_convert_inline_data(struct inode *inode);
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5153,7 +5153,8 @@ int ext4_fiemap(struct inode *inode, str
 	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;
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1816,11 +1816,12 @@ int ext4_destroy_inline_data(handle_t *h
 
 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;
 
@@ -1829,6 +1830,13 @@ int ext4_inline_data_fiemap(struct 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)
@@ -1837,11 +1845,10 @@ int ext4_inline_data_fiemap(struct 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);