aoe: user can ask driver to forget previously detected devices

When an AoE device is detected, the kernel is informed, and a new block device
is created.  If the device is unused, the block device corresponding to remote
device that is no longer available may be removed from the system by telling
the aoe driver to "flush" its list of devices.

Without this patch, software like GPFS and LVM may attempt to read from AoE
devices that were discovered earlier but are no longer present, blocking until
the I/O attempt times out.

Signed-off-by: Ed L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 68 insertions, 19 deletions

diff --git a/drivers/block/aoe/aoedev.c b/drivers/block/aoe/aoedev.c
index a4d625aefeaa..e26f6f4a28a2 100644
--- a/drivers/block/aoe/aoedev.c
+++ b/drivers/block/aoe/aoedev.c
@@ -9,6 +9,10 @@
 #include <linux/netdevice.h>
 #include "aoe.h"
 
+static void dummy_timer(ulong);
+static void aoedev_freedev(struct aoedev *);
+static void freetgt(struct aoetgt *t);
+
 static struct aoedev *devlist;
 static spinlock_t devlist_lock;
 
@@ -108,6 +112,70 @@ aoedev_downdev(struct aoedev *d)
         d->flags &= ~DEVFL_UP;
 }
 
+static void
+aoedev_freedev(struct aoedev *d)
+{
+        struct aoetgt **t, **e;
+
+        if (d->gd) {
+                aoedisk_rm_sysfs(d);
+                del_gendisk(d->gd);
+                put_disk(d->gd);
+        }
+        t = d->targets;
+        e = t + NTARGETS;
+        for (; t < e && *t; t++)
+                freetgt(*t);
+        if (d->bufpool)
+                mempool_destroy(d->bufpool);
+        kfree(d);
+}
+
+int
+aoedev_flush(const char __user *str, size_t cnt)
+{
+        ulong flags;
+        struct aoedev *d, **dd;
+        struct aoedev *rmd = NULL;
+        char buf[16];
+        int all = 0;
+
+        if (cnt >= 3) {
+                if (cnt > sizeof buf)
+                        cnt = sizeof buf;
+                if (copy_from_user(buf, str, cnt))
+                        return -EFAULT;
+                all = !strncmp(buf, "all", 3);
+        }
+
+        flush_scheduled_work();
+        spin_lock_irqsave(&devlist_lock, flags);
+        dd = &devlist;
+        while ((d = *dd)) {
+                spin_lock(&d->lock);
+                if ((!all && (d->flags & DEVFL_UP))
+                || (d->flags & (DEVFL_GDALLOC|DEVFL_NEWSIZE))
+                || d->nopen) {
+                        spin_unlock(&d->lock);
+                        dd = &d->next;
+                        continue;
+                }
+                *dd = d->next;
+                aoedev_downdev(d);
+                d->flags |= DEVFL_TKILL;
+                spin_unlock(&d->lock);
+                d->next = rmd;
+                rmd = d;
+        }
+        spin_unlock_irqrestore(&devlist_lock, flags);
+        while ((d = rmd)) {
+                rmd = d->next;
+                del_timer_sync(&d->timer);
+                aoedev_freedev(d);      /* must be able to sleep */
+        }
+        return 0;
+}
+
 /* find it or malloc it */
 struct aoedev *
 aoedev_by_sysminor_m(ulong sysminor)
@@ -161,25 +229,6 @@ freetgt(struct aoetgt *t)
         kfree(t);
 }
 
-static void
-aoedev_freedev(struct aoedev *d)
-{
-        struct aoetgt **t, **e;
-
-        if (d->gd) {
-                aoedisk_rm_sysfs(d);
-                del_gendisk(d->gd);
-                put_disk(d->gd);
-        }
-        t = d->targets;
-        e = t + NTARGETS;
-        for (; t < e && *t; t++)
-                freetgt(*t);
-        if (d->bufpool)
-                mempool_destroy(d->bufpool);
-        kfree(d);
-}
-
 void
 aoedev_exit(void)
 {