aoe: support the forgetting (flushing) of a user-specified AoE target

Users sometimes want to cause the aoe driver to forget a particular
previously discovered device when it is no longer online.  The aoetools
provide an "aoe-flush" command that users run to perform this
administrative task.  The changes below provide the support needed in the
driver.

Signed-off-by: Ed Cashin <ecashin@coraid.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 38 insertions, 6 deletions

diff --git a/drivers/block/aoe/aoedev.c b/drivers/block/aoe/aoedev.c
index 90e5b537f94b..63b26609400f 100644
--- a/drivers/block/aoe/aoedev.c
+++ b/drivers/block/aoe/aoedev.c
@@ -241,6 +241,30 @@ aoedev_freedev(struct aoedev *d)
         kfree(d);
 }
 
+/* return whether the user asked for this particular
+ * device to be flushed
+ */
+static int
+user_req(char *s, size_t slen, struct aoedev *d)
+{
+        char *p;
+        size_t lim;
+
+        if (!d->gd)
+                return 0;
+        p = strrchr(d->gd->disk_name, '/');
+        if (!p)
+                p = d->gd->disk_name;
+        else
+                p += 1;
+        lim = sizeof(d->gd->disk_name);
+        lim -= p - d->gd->disk_name;
+        if (slen < lim)
+                lim = slen;
+
+        return !strncmp(s, p, lim);
+}
+
 int
 aoedev_flush(const char __user *str, size_t cnt)
 {
@@ -249,6 +273,7 @@ aoedev_flush(const char __user *str, size_t cnt)
         struct aoedev *rmd = NULL;
         char buf[16];
         int all = 0;
+        int specified = 0;      /* flush a specific device */
 
         if (cnt >= 3) {
                 if (cnt > sizeof buf)
@@ -256,26 +281,33 @@ aoedev_flush(const char __user *str, size_t cnt)
                 if (copy_from_user(buf, str, cnt))
                         return -EFAULT;
                 all = !strncmp(buf, "all", 3);
+                if (!all)
+                        specified = 1;
         }
 
         spin_lock_irqsave(&devlist_lock, flags);
         dd = &devlist;
         while ((d = *dd)) {
                 spin_lock(&d->lock);
-                if ((!all && (d->flags & DEVFL_UP))
+                if (specified) {
+                        if (!user_req(buf, cnt, d))
+                                goto skip;
+                } else if ((!all && (d->flags & DEVFL_UP))
                 || (d->flags & (DEVFL_GDALLOC|DEVFL_NEWSIZE))
                 || d->nopen
-                || d->ref) {
-                        spin_unlock(&d->lock);
-                        dd = &d->next;
-                        continue;
-                }
+                || d->ref)
+                        goto skip;
+
                 *dd = d->next;
                 aoedev_downdev(d);
                 d->flags |= DEVFL_TKILL;
                 spin_unlock(&d->lock);
                 d->next = rmd;
                 rmd = d;
+                continue;
+skip:
+                spin_unlock(&d->lock);
+                dd = &d->next;
         }
         spin_unlock_irqrestore(&devlist_lock, flags);
         while ((d = rmd)) {