package/system/fstools/patches/0001-libfstools-fix-multiple-volume_identify-usages-with-.patch

   1 From 633a8d0981fed0c90f6d16ee2257858b04514dc8 Mon Sep 17 00:00:00 2001
   2 From: Pieter Smith <pieter.smith@philips.com>
   3 Date: Wed, 29 Mar 2017 18:21:56 +0200
   4 Subject: [PATCH] libfstools: fix multiple volume_identify usages with the same
   5  volume
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
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   9
  10 This fixes e.g. factory-flashed startup issue with jffs2 on ubi overlay
  11
  12 Commit ba019965 ("libfstools: accept volume as argument in most calls")
  13 broke startup for factory-flashed jffs2 on ubi systems, causing substantial
  14 slowdown in factory environments.
  15
  16 When starting up with a factory-flashed jffs2 on ubi system, the "rootfs_data"
  17 volume contains a deadcode marker. In the start phase, mount_root then mounts a
  18 tmpfs overlay, and postpones remounting of the jffs2 overlay until the done
  19 phase of the startup.
  20
  21 The refactoring in ba019965 eliminated an unneeded call to volume_find() when
  22 done() called jffs2_switch(). Unfortunately the refactoring did not take into
  23 account that volume_identify() does not function correctly when called twice in
  24 a row on the same struct volume when using an mtd driver.
  25
  26 mtd_volume_identify() uses mtd_volume_load() to open an fd to the mtd device
  27 and reads a potential deadcode marker from the fd. The first time this works,
  28 and FS_DEADCODE is returned.
  29
  30 When volume_identify() is called a second time however, mtd_volume_load()
  31 notices that we already have an open fd, does nothing further and returns 0
  32 without resetting the file offset to 0. mtd_volume_identify() now reads past
  33 the deadcode marker and now returns FS_JFFS2 if the mtd device is a UBIVOLUME.
  34
  35 jffs2_switch() then handles the wrong case, either pulling the root out from
  36 under user-space in Chaos Calmer, or indefinitely sticking to a tmpfs overlay
  37 in later OpenWRT builds.
  38
  39 Signed-off-by: Pieter Smith <pieter.smith@philips.com>
  40 Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
  41 ---
  42
  43 --- a/libfstools/mtd.c
  44 +++ b/libfstools/mtd.c
  45 @@ -76,8 +76,10 @@ static int mtd_volume_load(struct mtd_vo
  46         struct mtd_info_user mtdInfo;
  47         struct erase_info_user mtdLockInfo;
  48
  49 -       if (p->fd)
  50 +       if (p->fd) {
  51 +               lseek(p->fd, 0, SEEK_SET);
  52                 return 0;
  53 +       }
  54
  55         if (!p->chr)
  56                 return -1;