Re: [Libguestfs] [PATCH supermin] ext2: Create symlinks properly (RHBZ#1470157).

The ext2 filesystem on disk format has two ways to store symlinks. For symlinks >= 60 bytes in length, they are stored as files (so-called "slow symlinks"). For shorter symlinks the symlink is stored in the inode ("fast symlinks"). Previously we only created slow symlinks even if there are shorter than 60 bytes. This didn't matter until recently, when a change went upstream which assumes that symlinks shorter than 60 bytes are always stored in the inode, thus breaking the filesystems that we created before: https://bugzilla.redhat.com/show_bug.cgi?id=1470157#c4 This changes the code to use the ext2fs_symlink function instead which creates fast and slow symlinks properly. This fix is required if you use supermin with any Linux kernel >= 4.13. The actual fix is two lines replacing ext2_write_file with a simpler call to ext2fs_symlink. The majority of this fix is removing the ext2_write_file function which is no longer referenced after that change. Thanks: Eric Sandeen ---

@@ -833,7 +792,8 @@ ext2_copy_file (struct ext2_data *data, const char *src, const char *dest) ssize_t r = readlink (src, buf, sizeof buf); if (r == -1) unix_error (errno, (char *) "readlink", caml_copy_string (src)); - ext2_write_file (data->fs, ino, buf, r, dest); + buf[r] = '\0'; + ext2fs_symlink (data->fs, dir_ino, ino, dest, buf);