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Date: Fri, 02 Feb 2007 13:50:10 -1000
From: akuster@...sta.com
To: linux-kernel@...r.kernel.org
Cc: akpm@...l.org
Subject: [patch 1/1] PM: Adds remount fs ro at suspend
This adds the ability for the file system to remounted as read only during a
system suspend. Log the mount points so when the resume occurs, they can be
remounted back to their original states. This is so in an advent of a power
failure, we try our best to keep data from being corrupted or lost.
Signed-of-by: Armin Kuster <AKuster@...sta.com>
---
fs/super.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/power/Kconfig | 11 ++++++++
kernel/power/main.c | 13 +++++++++
kernel/power/power.h | 6 ++++
4 files changed, 97 insertions(+)
diff -puN fs/super.c~suspend_fs_ro fs/super.c
--- linux-2.6_sdio/fs/super.c~suspend_fs_ro 2007-02-01 13:35:46.000000000 -1000
+++ linux-2.6_sdio-akuster/fs/super.c 2007-02-01 13:35:50.000000000 -1000
@@ -47,6 +47,70 @@ struct file_system_type *get_fs_type(con
LIST_HEAD(super_blocks);
DEFINE_SPINLOCK(sb_lock);
+#ifdef CONFIG_SUSPEND_REMOUNTFS
+/*
+ * Code to preserve filesystem data during suspend.
+ */
+
+struct suspremount {
+struct super_block *sb;
+struct suspremount *next;
+};
+
+static struct suspremount *suspremount_list;
+
+void suspend_remount_log_fs(struct super_block *sb)
+{
+ struct suspremount *remountp;
+
+ if ((remountp = (struct suspremount *)
+ kmalloc(sizeof(struct suspremount), GFP_KERNEL)) != NULL) {
+ remountp->sb = sb;
+ remountp->next = suspremount_list;
+ suspremount_list = remountp;
+ }
+}
+
+/*
+ * Remount filesystems prior to suspend, in case the
+ * power source is removed (ie, battery removed) or
+ * battery dies during suspend.
+ */
+
+void suspend_remount_all_fs_ro(void)
+{
+ suspremount_list = NULL;
+ emergency_remount();
+}
+EXPORT_SYMBOL(suspend_remount_all_fs_ro);
+
+void resume_remount_fs_rw(void)
+{
+ struct suspremount *remountp;
+
+ remountp = suspremount_list;
+
+ while (remountp != NULL) {
+ struct suspremount *tp;
+ struct super_block *sb;
+ int flags, ret;
+
+ sb = remountp->sb;
+ flags = 0;
+ if (sb->s_op && sb->s_op->remount_fs) {
+ ret = sb->s_op->remount_fs(sb, &flags, NULL);
+ if (ret) printk("resume_remount_rw: error %d\n", ret);
+ }
+
+ tp = remountp->next;
+ kfree(remountp);
+ remountp = tp;
+ }
+ suspremount_list = NULL;
+}
+EXPORT_SYMBOL(resume_remount_fs_rw);
+#endif
+
/**
* alloc_super - create new superblock
* @type: filesystem type superblock should belong to
@@ -613,6 +677,9 @@ int do_remount_sb(struct super_block *sb
unlock_super(sb);
if (retval)
return retval;
+#ifdef CONFIG_SUSPEND_REMOUNTFS
+ suspend_remount_log_fs(sb);
+#endif
}
sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
return 0;
diff -puN kernel/power/Kconfig~suspend_fs_ro kernel/power/Kconfig
--- linux-2.6_sdio/kernel/power/Kconfig~suspend_fs_ro 2007-02-01 13:52:42.000000000 -1000
+++ linux-2.6_sdio-akuster/kernel/power/Kconfig 2007-02-02 06:20:13.000000000 -1000
@@ -131,3 +131,14 @@ config SUSPEND_SMP
bool
depends on HOTPLUG_CPU && X86 && PM
default y
+
+config SUSPEND_REMOUNTFS
+ bool "Remount file system as ro on suspend"
+ depends on PM
+ default n
+ ---help---
+ Say Y here if you want to remount filesystems as read only
+ prior to suspend, in case the power source is
+ removed (ie, battery removed) or battery dies during suspend.
+ Upon resume, file system mount state is restored.
+
diff -puN kernel/power/main.c~suspend_fs_ro kernel/power/main.c
--- linux-2.6_sdio/kernel/power/main.c~suspend_fs_ro 2007-02-01 13:57:56.000000000 -1000
+++ linux-2.6_sdio-akuster/kernel/power/main.c 2007-02-01 13:58:08.000000000 -1000
@@ -67,6 +67,16 @@ static int suspend_prepare(suspend_state
if (error)
goto Enable_cpu;
+#ifdef CONFIG_SUSPEND_REMOUNTFS
+ /*
+ * Remount filesystems prior to suspend, in case the
+ * power source is removed (ie, battery removed) or
+ * battery dies during suspend.
+ */
+
+ suspend_remount_all_fs_ro();
+#endif
+
if (freeze_processes()) {
error = -EAGAIN;
goto Thaw;
@@ -97,6 +107,9 @@ static int suspend_prepare(suspend_state
if (pm_ops->finish)
pm_ops->finish(state);
Thaw:
+#ifdef CONFIG_SUSPEND_REMOUNTFS
+ resume_remount_fs_rw();
+#endif
thaw_processes();
Enable_cpu:
enable_nonboot_cpus();
diff -puN kernel/power/power.h~suspend_fs_ro kernel/power/power.h
--- linux-2.6_sdio/kernel/power/power.h~suspend_fs_ro 2007-02-01 13:58:49.000000000 -1000
+++ linux-2.6_sdio-akuster/kernel/power/power.h 2007-02-01 13:59:03.000000000 -1000
@@ -177,3 +177,9 @@ extern int suspend_enter(suspend_state_t
struct timeval;
extern void swsusp_show_speed(struct timeval *, struct timeval *,
unsigned int, char *);
+
+/* remount file system read only on suspend
+ * and retore to rw on resume
+ */
+extern void suspend_remount_all_fs_ro(void);
+extern void resume_remount_fs_rw(void);
_
-
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