[PATCH v1 3/5] ntfs: initialize packed EA size when creating hard links

[Baolin Liu <liubaolin12138@163.com>]

From: Xuewen Wang <wangxuewen@kylinos.cn>

A new hard link has a zero packed EA size in its FILE_NAME even when
the source file already has extended attributes.

For files with EAs and no reparse point, read EA_INFORMATION and check
its attribute length before adding the name. Copy its ea_length into
the new FILE_NAME's packed_ea_size. Skip this assignment for reparse
points, where the same storage holds the reparse-point tag.

Suggested-by: Baolin Liu <liubaolin@kylinos.cn>
Signed-off-by: Xuewen Wang <wangxuewen@kylinos.cn>
---
Tested with the complete five-patch series in QEMU. Published an
O_TMPFILE after inheriting an access ACL and setting a 12000-byte EA.
Offline ntfsinfo inspection confirms that the FILE_NAME attribute in
the file's MFT record has the same packed EA length as EA_INFORMATION
(12134 bytes). The 12000-byte EA contents also match after cache eviction,
remount and a fresh boot.

 fs/ntfs/namei.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/fs/ntfs/namei.c b/fs/ntfs/namei.c
index 4442e1d..b26fd9c 100644
--- a/fs/ntfs/namei.c
+++ b/fs/ntfs/namei.c
@@ -1316,6 +1316,24 @@ static int __ntfs_link(struct ntfs_inode *ni, struct ntfs_inode *dir_ni,
 	fn->last_access_time = utc2ntfs(inode_get_atime(vi));
 	memcpy(fn->file_name, name, name_len * sizeof(__le16));
 
+	if (NInoHasEA(ni) && !(ni->flags & FILE_ATTR_REPARSE_POINT)) {
+		struct ea_information *info;
+		s64 size;
+
+		info = ntfs_attr_readall(ni, AT_EA_INFORMATION, AT_UNNAMED, 0, &size);
+		if (IS_ERR(info)) {
+			err = PTR_ERR(info);
+			goto err_out;
+		}
+		if (size != sizeof(*info))
+			err = -EUCLEAN;
+		else
+			fn->type.ea.packed_ea_size = info->ea_length;
+		kvfree(info);
+		if (err)
+			goto err_out;
+	}
+
 	/* Add FILE_NAME attribute to index. */
 	err = ntfs_index_add_filename(dir_ni, fn, MK_MREF(ni->mft_no,
 					le16_to_cpu(ni_mrec->sequence_number)));