(Adding Cc: Matthew Wilcox)
Pekka J Enberg wrote:
Add a new kernel config option CONFIG_LATE_ROOT_MOUNT that makes the kernel
wait until background scanning of USB mass storage devices is complete before
attempting to mount the root filesystem.
The config option is an alternative to the root_delay= kernel parameter
solution people currently use to boot from USB mass storage devices.
[...]
drivers/scsi/scsi_scan.c | 2 ++
drivers/usb/storage/usb.c | 3 +++
include/linux/init.h | 12 ++++++++++++
init/Kconfig | 5 +++++
init/do_mounts.c | 32 ++++++++++++++++++++++++++++++++
5 files changed, 54 insertions(+)
Index: linux-2.6/drivers/usb/storage/usb.c
===================================================================
--- linux-2.6.orig/drivers/usb/storage/usb.c
+++ linux-2.6/drivers/usb/storage/usb.c
@@ -928,6 +928,7 @@ static int usb_stor_scan_thread(void * _
/* Should we unbind if no devices were detected? */
}
+ complete_root_scan();
complete_and_exit(&us->scanning_done, 0);
}
@@ -1007,12 +1008,14 @@ static int storage_probe(struct usb_inte
goto BadDevice;
}
+ begin_root_scan();
/* Start up the thread for delayed SCSI-device scanning */
th = kthread_create(usb_stor_scan_thread, us, "usb-stor-scan");
if (IS_ERR(th)) {
printk(KERN_WARNING USB_STORAGE
"Unable to start the device-scanning thread\n");
quiesce_and_remove_host(us);
+ complete_root_scan();
result = PTR_ERR(th);
goto BadDevice;
}
[...]
Index: linux-2.6/drivers/scsi/scsi_scan.c
===================================================================
--- linux-2.6.orig/drivers/scsi/scsi_scan.c
+++ linux-2.6/drivers/scsi/scsi_scan.c
@@ -1802,6 +1802,7 @@ static int do_scan_async(void *_data)
struct async_scan_data *data = _data;
do_scsi_scan_host(data->shost);
scsi_finish_async_scan(data);
+ complete_root_scan();
return 0;
}
@@ -1823,6 +1824,7 @@ void scsi_scan_host(struct Scsi_Host *sh
return;
}
+ begin_root_scan();
p = kthread_run(do_scan_async, data, "scsi_scan_%d", shost->host_no);
if (unlikely(IS_ERR(p)))
do_scan_async(data);
Looks like you want complete_root_scan() after IS_ERR(p). Are there any
other thread exit paths which don't call complete_root_scan() yet?
Besides, can't you use the generic async scan facility of the SCSI stack
for your purpose? If not, can it be extended to make it usable?
--
Stefan Richter
-=====-==--- -=-- ==--=
http://arcgraph.de/sr/
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