Make wait_for_device_probe() also do scsi_complete_async_scans()

Commit a7a20d103994 ("sd: limit the scope of the async probe domain")
make the SCSI device probing run device discovery in it's own async
domain.

However, as a result, the partition detection was no longer synchronized
by async_synchronize_full() (which, despite the name, only synchronizes
the global async space, not all of them).  Which in turn meant that
"wait_for_device_probe()" would not wait for the SCSI partitions to be
parsed.

And "wait_for_device_probe()" was what the boot time init code relied on
for mounting the root filesystem.

Now, most people never noticed this, because not only is it
timing-dependent, but modern distributions all use initrd.  So the root
filesystem isn't actually on a disk at all.  And then before they
actually mount the final disk filesystem, they will have loaded the
scsi-wait-scan module, which not only does the expected
wait_for_device_probe(), but also does scsi_complete_async_scans().

[ Side note: scsi_complete_async_scans() had also been partially broken,
  but that was fixed in commit 43a8d39d0137 ("fix async probe
  regression"), so that same commit a7a20d103994 had actually broken
  setups even if you used scsi-wait-scan explicitly ]

Solve this problem by just moving the scsi_complete_async_scans() call
into wait_for_device_probe().  Everybody who wants to wait for device
probing to finish really wants the SCSI probing to complete, so there's
no reason not to do this.

So now "wait_for_device_probe()" really does what the name implies, and
properly waits for device probing to finish.  This also removes the now
unnecessary extra calls to scsi_complete_async_scans().

Reported-and-tested-by: Artem S. Tashkinov <t.artem@mailcity.com>
Cc: Dan Williams <dan.j.williams@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: Borislav Petkov <bp@amd64.org>
Cc: linux-scsi <linux-scsi@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index dcb8a6e..4b01ab3 100644 (file)
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -24,6 +24,7 @@
 #include <linux/wait.h>
 #include <linux/async.h>
 #include <linux/pm_runtime.h>
+#include <scsi/scsi_scan.h>
 
 #include "base.h"
 #include "power/power.h"
@@ -332,6 +333,7 @@ void wait_for_device_probe(void)
        /* wait for the known devices to complete their probing */
        wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
        async_synchronize_full();
+       scsi_complete_async_scans();
 }
 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 

diff --git a/drivers/scsi/scsi_wait_scan.c b/drivers/scsi/scsi_wait_scan.c
index ae78148..0727345 100644 (file)
--- a/drivers/scsi/scsi_wait_scan.c
+++ b/drivers/scsi/scsi_wait_scan.c
@@ -22,11 +22,6 @@ static int __init wait_scan_init(void)
         * and might not yet have reached the scsi async scanning
         */
        wait_for_device_probe();
-       /*
-        * and then we wait for the actual asynchronous scsi scan
-        * to finish.
-        */
-       scsi_complete_async_scans();
        return 0;
 }
 

diff --git a/include/linux/device.h b/include/linux/device.h
index 161d962..6de9415 100644 (file)
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -865,8 +865,6 @@ extern int (*platform_notify_remove)(struct device *dev);
 extern struct device *get_device(struct device *dev);
 extern void put_device(struct device *dev);
 
-extern void wait_for_device_probe(void);
-
 #ifdef CONFIG_DEVTMPFS
 extern int devtmpfs_create_node(struct device *dev);
 extern int devtmpfs_delete_node(struct device *dev);

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 8b53db3..238025f 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -27,7 +27,6 @@
 #include <linux/syscore_ops.h>
 #include <linux/ctype.h>
 #include <linux/genhd.h>
-#include <scsi/scsi_scan.h>
 
 #include "power.h"
 
@@ -748,13 +747,6 @@ static int software_resume(void)
                        async_synchronize_full();
                }
 
-               /*
-                * We can't depend on SCSI devices being available after loading
-                * one of their modules until scsi_complete_async_scans() is
-                * called and the resume device usually is a SCSI one.
-                */
-               scsi_complete_async_scans();
-
                swsusp_resume_device = name_to_dev_t(resume_file);
                if (!swsusp_resume_device) {
                        error = -ENODEV;

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 91b0fd0..4ed81e7 100644 (file)
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -24,7 +24,6 @@
 #include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/freezer.h>
-#include <scsi/scsi_scan.h>
 
 #include <asm/uaccess.h>
 
@@ -84,7 +83,6 @@ static int snapshot_open(struct inode *inode, struct file *filp)
                 * appear.
                 */
                wait_for_device_probe();
-               scsi_complete_async_scans();
 
                data->swap = -1;
                data->mode = O_WRONLY;