fs/ntfs3: Update inode->i_mapping->a_ops on compression state change

Update inode->i_mapping->a_ops when the compression state changes to
ensure correct address space operations.
Clear ATTR_FLAG_SPARSED/FILE_ATTRIBUTE_SPARSE_FILE when enabling
compression to prevent flag conflicts.

Fixes: 6b39bfa ("fs/ntfs3: Add support for the compression attribute")
Reported-by: Kun Hu <huk23@m.fudan.edu.cn>, Jiaji Qin <jjtan24@m.fudan.edu.cn>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/attrib.c

@@ -2666,6 +2666,7 @@ int attr_set_compress(struct ntfs_inode *ni, bool compr)
 
 	/* Update data attribute flags. */
 	if (compr) {
+		attr->flags &= ATTR_FLAG_SPARSED;
 		attr->flags |= ATTR_FLAG_COMPRESSED;
 		attr->nres.c_unit = NTFS_LZNT_CUNIT;
 	} else {

fs/ntfs3/file.c

@@ -105,6 +105,8 @@ int ntfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
 		int err = ni_set_compress(inode, flags & FS_COMPR_FL);
 		if (err)
 			return err;
+		inode->i_mapping->a_ops =
+			(flags & FS_COMPR_FL) ? &ntfs_aops_cmpr : &ntfs_aops;
 	}
 
 	inode_set_flags(inode, new_fl, S_IMMUTABLE | S_APPEND);

fs/ntfs3/frecord.c

@@ -3434,10 +3434,12 @@ int ni_set_compress(struct inode *inode, bool compr)
 	}
 
 	ni->std_fa = std->fa;
-	if (compr)
+	if (compr) {
+		std->fa &= ~FILE_ATTRIBUTE_SPARSE_FILE;
 		std->fa |= FILE_ATTRIBUTE_COMPRESSED;
-	else
+	} else {
 		std->fa &= ~FILE_ATTRIBUTE_COMPRESSED;
+	}
 
 	if (ni->std_fa != std->fa) {
 		ni->std_fa = std->fa;