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