Messages in this thread | | | Date | Thu, 3 Mar 2011 16:49:56 +0800 | Subject | Re: [PATCH] Syscalls: reboot: Add options to the reboot syscall to remount filesystems ro | From | Dave Young <> |
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On Thu, Mar 3, 2011 at 4:46 PM, Dave Young <hidave.darkstar@gmail.com> wrote: > On Thu, Mar 3, 2011 at 3:31 PM, Ken Sumrall <ksumrall@android.com> wrote: >> Add 4 new commands to the reboot system call, that do the same thing as the >> RESTART, HALT, POWER_OFF, and RESTART2 commands, but also remount writable >> filesystems as read-only just before doing what the command normally does. >> Now that Android is using EXT4, and since we don't have a standard init >> setup to unmount filesystems before rebooting, this allows the system to >> reboot with clean filesystems, and also improves boot time as the journal >> does not need to be replayed when mounting the filesystem. >> >> Signed-off-by: Ken Sumrall <ksumrall@android.com> >> --- >> fs/super.c | 9 +++++++++ >> include/linux/fs.h | 1 + >> include/linux/reboot.h | 4 ++++ >> kernel/sys.c | 12 ++++++++++++ >> 4 files changed, 26 insertions(+), 0 deletions(-) >> >> diff --git a/fs/super.c b/fs/super.c >> index 8819e3a..3f39a16 100644 >> --- a/fs/super.c >> +++ b/fs/super.c >> @@ -638,6 +638,15 @@ void emergency_remount(void) >> } >> } >> >> +void emergency_remount_synchronous(void) >> +{ >> + struct work_struct *work; >> + >> + work = kmalloc(sizeof(*work), GFP_ATOMIC); >> + if (work) >> + do_emergency_remount(work); > > work is not needed here? just call do_mergency_remount()
fix above comment: still need a null pointer
> >> +} >> + >> /* >> * Unnamed block devices are dummy devices used by virtual >> * filesystems which don't use real block-devices. -- jrs >> diff --git a/include/linux/fs.h b/include/linux/fs.h >> index 63d069b..e48ef0d 100644 >> --- a/include/linux/fs.h >> +++ b/include/linux/fs.h >> @@ -2110,6 +2110,7 @@ extern int generic_write_sync(struct file *file, loff_t pos, loff_t count); >> extern void sync_supers(void); >> extern void emergency_sync(void); >> extern void emergency_remount(void); >> +extern void emergency_remount_synchronous(void); >> #ifdef CONFIG_BLOCK >> extern sector_t bmap(struct inode *, sector_t); >> #endif >> diff --git a/include/linux/reboot.h b/include/linux/reboot.h >> index 3005d5a..24b185d 100644 >> --- a/include/linux/reboot.h >> +++ b/include/linux/reboot.h >> @@ -26,11 +26,15 @@ >> */ >> >> #define LINUX_REBOOT_CMD_RESTART 0x01234567 >> +#define LINUX_REBOOT_CMD_RMNT_RESTART 0x12345670 >> #define LINUX_REBOOT_CMD_HALT 0xCDEF0123 >> +#define LINUX_REBOOT_CMD_RMNT_HALT 0xDEF0123C >> #define LINUX_REBOOT_CMD_CAD_ON 0x89ABCDEF >> #define LINUX_REBOOT_CMD_CAD_OFF 0x00000000 >> #define LINUX_REBOOT_CMD_POWER_OFF 0x4321FEDC >> +#define LINUX_REBOOT_CMD_RMNT_POWER_OFF 0x321FEDC4 >> #define LINUX_REBOOT_CMD_RESTART2 0xA1B2C3D4 >> +#define LINUX_REBOOT_CMD_RMNT_RESTART2 0x1B2C3D4A >> #define LINUX_REBOOT_CMD_SW_SUSPEND 0xD000FCE2 >> #define LINUX_REBOOT_CMD_KEXEC 0x45584543 >> >> diff --git a/kernel/sys.c b/kernel/sys.c >> index 7f5a0cd..3f474e6 100644 >> --- a/kernel/sys.c >> +++ b/kernel/sys.c >> @@ -392,6 +392,9 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, >> mutex_lock(&reboot_mutex); >> switch (cmd) { >> case LINUX_REBOOT_CMD_RESTART: >> + case LINUX_REBOOT_CMD_RMNT_RESTART: >> + if (cmd == LINUX_REBOOT_CMD_RMNT_RESTART) >> + emergency_remount_synchronous(); >> kernel_restart(NULL); >> break; >> >> @@ -404,22 +407,31 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, >> break; >> >> case LINUX_REBOOT_CMD_HALT: >> + case LINUX_REBOOT_CMD_RMNT_HALT: >> + if (cmd == LINUX_REBOOT_CMD_RMNT_HALT) >> + emergency_remount_synchronous(); >> kernel_halt(); >> do_exit(0); >> panic("cannot halt"); >> >> case LINUX_REBOOT_CMD_POWER_OFF: >> + case LINUX_REBOOT_CMD_RMNT_POWER_OFF: >> + if (cmd == LINUX_REBOOT_CMD_RMNT_POWER_OFF) >> + emergency_remount_synchronous(); >> kernel_power_off(); >> do_exit(0); >> break; >> >> case LINUX_REBOOT_CMD_RESTART2: >> + case LINUX_REBOOT_CMD_RMNT_RESTART2: >> if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) { >> ret = -EFAULT; >> break; >> } >> buffer[sizeof(buffer) - 1] = '\0'; >> >> + if (cmd == LINUX_REBOOT_CMD_RMNT_RESTART2) >> + emergency_remount_synchronous(); >> kernel_restart(buffer); >> break; >> >> -- >> 1.7.3.1 >> >> > > > > -- > Regards > dave >
-- Regards dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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