target/linux/generic/pending-5.4/553-ubifs-Add-option-to-create-UBI-FS-version-4-on-empty.patch

   1 From 93c33e6a7f3b0aef99d02252e6232a3d8b80f2d5 Mon Sep 17 00:00:00 2001
   2 From: Hauke Mehrtens <hauke@hauke-m.de>
   3 Date: Sun, 21 Jan 2018 15:47:50 +0100
   4 Subject: ubifs: Add option to create UBI FS version 4 on empty UBI volume
   5
   6 Instead of creating an ubifs file system with format version 5 by
   7 default on empty UBI volumes add a compile option to create an older ubi
   8 with file system format version 4 instated. This allows it to be mount
   9 as a volume on kernel versions < 4.10, which does not support format
  10 version 5.
  11 We saw that some people can not access their older data when they
  12 downgraded from kernel 4.14 to kernel 4.9 to prevent this this option
  13 would help.
  14
  15 Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
  16 ---
  17  fs/ubifs/Kconfig | 13 +++++++++++++
  18  fs/ubifs/sb.c    |  6 ++++++
  19  2 files changed, 19 insertions(+)
  20
  21 --- a/fs/ubifs/Kconfig
  22 +++ b/fs/ubifs/Kconfig
  23 @@ -85,6 +85,19 @@ config UBIFS_FS_SECURITY
  24
  25           If you are not using a security module, say N.
  26
  27 +config UBIFS_FS_FORMAT4
  28 +       bool "Use file system format version 4 for new file systems"
  29 +       depends on UBIFS_FS
  30 +       help
  31 +         Instead of creating new file systems with the new ubifs file
  32 +         system version 5, use the old format version 4 for implicitly
  33 +         by the driver created file systems on an empty UBI volume. This
  34 +         makes it possible to  mount these file systems also with kernel
  35 +         versions before 4.10. The driver will still support file system
  36 +         format version 5 for ubifs file systems created with version 5.
  37 +
  38 +         If you are unsure, say N.
  39 +
  40  config UBIFS_FS_AUTHENTICATION
  41         bool "UBIFS authentication support"
  42         select KEYS
  43 --- a/fs/ubifs/sb.c
  44 +++ b/fs/ubifs/sb.c
  45 @@ -175,7 +175,9 @@ static int create_default_filesystem(str
  46         tmp64 = (long long)max_buds * c->leb_size;
  47         if (big_lpt)
  48                 sup_flags |= UBIFS_FLG_BIGLPT;
  49 +#ifndef CONFIG_UBIFS_FS_FORMAT4
  50         sup_flags |= UBIFS_FLG_DOUBLE_HASH;
  51 +#endif
  52
  53         if (ubifs_authenticated(c)) {
  54                 sup_flags |= UBIFS_FLG_AUTHENTICATION;
  55 @@ -201,7 +203,11 @@ static int create_default_filesystem(str
  56         sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
  57         sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
  58         sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
  59 +#ifdef CONFIG_UBIFS_FS_FORMAT4
  60 +       sup->fmt_version   = cpu_to_le32(4);
  61 +#else
  62         sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
  63 +#endif
  64         sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
  65         if (c->mount_opts.override_compr)
  66                 sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);