[PATCH 2/7] aoe: retain static block device numbers for backwards compatibility

[Ed Cashin]

The old mapping between AoE target shelf and slot addresses and
the block device minor number is retained as a
backwards-compatible feature, with a new "aoe_dyndevs" module
parameter available for enabling dynamic block device minor
numbers.

Signed-off-by: Ed Cashin <ecas...@coraid.com>
---
 drivers/block/aoe/aoedev.c |   54 +++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/drivers/block/aoe/aoedev.c b/drivers/block/aoe/aoedev.c
index 68a7a5a..3d494fd 100644
--- a/drivers/block/aoe/aoedev.c
+++ b/drivers/block/aoe/aoedev.c
@@ -11,6 +11,7 @@
 #include <linux/slab.h>
 #include <linux/bitmap.h>
 #include <linux/kdev_t.h>
+#include <linux/moduleparam.h>
 #include "aoe.h"
 
 static void dummy_timer(ulong);
@@ -18,6 +19,10 @@ static void aoedev_freedev(struct aoedev *);
 static void freetgt(struct aoedev *d, struct aoetgt *t);
 static void skbpoolfree(struct aoedev *d);
 
+static int aoe_dyndevs;
+module_param(aoe_dyndevs, int, 0644);
+MODULE_PARM_DESC(aoe_dyndevs, "Use dynamic minor numbers for devices.");
+
 static struct aoedev *devlist;
 static DEFINE_SPINLOCK(devlist_lock);
 
@@ -34,7 +39,7 @@ static DEFINE_SPINLOCK(used_minors_lock);
 static DECLARE_BITMAP(used_minors, N_DEVS);
 
 static int
-minor_get(ulong *minor)
+minor_get_dyn(ulong *sysminor)
 {
        ulong flags;
        ulong n;
@@ -48,10 +53,53 @@ minor_get(ulong *minor)
                error = -1;
        spin_unlock_irqrestore(&used_minors_lock, flags);
 
-       *minor = n * AOE_PARTITIONS;
+       *sysminor = n * AOE_PARTITIONS;
        return error;
 }
 
+static int
+minor_get_static(ulong *sysminor, ulong aoemaj, int aoemin)
+{
+       ulong flags;
+       ulong n;
+       int error = 0;
+       enum {
+               /* for backwards compatibility when !aoe_dyndevs,
+                * a static number of supported slots per shelf */
+               NPERSHELF = 16,
+       };
+
+       n = aoemaj * NPERSHELF + aoemin;
+       if (aoemin >= NPERSHELF || n >= N_DEVS) {
+               pr_err("aoe: %s with e%ld.%d\n",
+                       "cannot use static minor device numbers",
+                       aoemaj, aoemin);
+               error = -1;
+       } else {
+               spin_lock_irqsave(&used_minors_lock, flags);
+               if (test_bit(n, used_minors)) {
+                       pr_err("aoe: %s %lu\n",
+                               "existing device already has static minor 
number",
+                               n);
+                       error = -1;
+               } else
+                       set_bit(n, used_minors);
+               spin_unlock_irqrestore(&used_minors_lock, flags);
+       }
+
+       *sysminor = n;
+       return error;
+}
+
+static int
+minor_get(ulong *sysminor, ulong aoemaj, int aoemin)
+{
+       if (aoe_dyndevs)
+               return minor_get_dyn(sysminor);
+       else
+               return minor_get_static(sysminor, aoemaj, aoemin);
+}
+
 static void
 minor_free(ulong minor)
 {
@@ -293,7 +341,7 @@ aoedev_by_aoeaddr(ulong maj, int min, int do_alloc)
                        d->ref++;
                        break;
                }
-       if (d || !do_alloc || minor_get(&sysminor) < 0)
+       if (d || !do_alloc || minor_get(&sysminor, maj, min) < 0)
                goto out;
        d = kcalloc(1, sizeof *d, GFP_ATOMIC);
        if (!d)
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/