ext4: fix readdir error in the case of inline_data+dir_index

Zach reported a problem that if inline data is enabled, we don't
tell the difference between the offset of '.' and '..'. And a
getdents will fail if the user only want to get '.' and what's worse,
if there is a conversion happens when the user calls getdents
many times, he/she may get the same entry twice.

In theory, a dir block would also fail if it is converted to a
hashed-index based dir since f_pos will become a hash value, not the
real one, but it doesn't happen.  And a deep investigation shows that
we uses a hash based solution even for a normal dir if the dir_index
feature is enabled.

So this patch just adds a new htree_inlinedir_to_tree for inline dir,
and if we find that the hash index is supported, we will do like what
we do for a dir block.

Reported-by: Zach Brown <zab@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 11 insertions, 9 deletions

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index d8cd1f0f4661..f8d56e4254e0 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -46,7 +46,8 @@ static int is_dx_dir(struct inode *inode)
 	if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
 		     EXT4_FEATURE_COMPAT_DIR_INDEX) &&
 	    ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
-	     ((inode->i_size >> sb->s_blocksize_bits) == 1)))
+	     ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
+	     ext4_has_inline_data(inode)))
 		return 1;
 
 	return 0;
@@ -115,14 +116,6 @@ static int ext4_readdir(struct file *filp,
 	int ret = 0;
 	int dir_has_error = 0;
 
-	if (ext4_has_inline_data(inode)) {
-		int has_inline_data = 1;
-		ret = ext4_read_inline_dir(filp, dirent, filldir,
-					   &has_inline_data);
-		if (has_inline_data)
-			return ret;
-	}
-
 	if (is_dx_dir(inode)) {
 		err = ext4_dx_readdir(filp, dirent, filldir);
 		if (err != ERR_BAD_DX_DIR) {
@@ -136,6 +129,15 @@ static int ext4_readdir(struct file *filp,
 		ext4_clear_inode_flag(file_inode(filp),
 				      EXT4_INODE_INDEX);
 	}
+
+	if (ext4_has_inline_data(inode)) {
+		int has_inline_data = 1;
+		ret = ext4_read_inline_dir(filp, dirent, filldir,
+					   &has_inline_data);
+		if (has_inline_data)
+			return ret;
+	}
+
 	stored = 0;
 	offset = filp->f_pos & (sb->s_blocksize - 1);