Merge branch 'stable/xen-pcifront-0.8.2' of git://git.kernel.org/pub/scm/linux/kernel...

[karo-tx-linux.git] / drivers / block / xen-blkfront.c

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index c4e9d817caaa68b8a30ffccf5d9b77a113c6719a..06e2812ba12405dc0a63eea531943b53c4aa067b 100644 (file)
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -41,7 +41,7 @@
 #include <linux/cdrom.h>
 #include <linux/module.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
+#include <linux/mutex.h>
 #include <linux/scatterlist.h>
 
 #include <xen/xen.h>
@@ -69,6 +69,7 @@ struct blk_shadow {
        unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 };
 
+static DEFINE_MUTEX(blkfront_mutex);
 static const struct block_device_operations xlvbd_block_fops;
 
 #define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
@@ -95,7 +96,7 @@ struct blkfront_info
        struct gnttab_free_callback callback;
        struct blk_shadow shadow[BLK_RING_SIZE];
        unsigned long shadow_free;
-       int feature_barrier;
+       unsigned int feature_flush;
        int is_ready;
 };
 
@@ -418,26 +419,12 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
 }
 
 
-static int xlvbd_barrier(struct blkfront_info *info)
+static void xlvbd_flush(struct blkfront_info *info)
 {
-       int err;
-       const char *barrier;
-
-       switch (info->feature_barrier) {
-       case QUEUE_ORDERED_DRAIN:       barrier = "enabled (drain)"; break;
-       case QUEUE_ORDERED_TAG:         barrier = "enabled (tag)"; break;
-       case QUEUE_ORDERED_NONE:        barrier = "disabled"; break;
-       default:                        return -EINVAL;
-       }
-
-       err = blk_queue_ordered(info->rq, info->feature_barrier);
-
-       if (err)
-               return err;
-
+       blk_queue_flush(info->rq, info->feature_flush);
        printk(KERN_INFO "blkfront: %s: barriers %s\n",
-              info->gd->disk_name, barrier);
-       return 0;
+              info->gd->disk_name,
+              info->feature_flush ? "enabled" : "disabled");
 }
 
 
@@ -516,7 +503,7 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
        info->rq = gd->queue;
        info->gd = gd;
 
-       xlvbd_barrier(info);
+       xlvbd_flush(info);
 
        if (vdisk_info & VDISK_READONLY)
                set_disk_ro(gd, 1);
@@ -662,8 +649,8 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
                                printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
                                       info->gd->disk_name);
                                error = -EOPNOTSUPP;
-                               info->feature_barrier = QUEUE_ORDERED_NONE;
-                               xlvbd_barrier(info);
+                               info->feature_flush = 0;
+                               xlvbd_flush(info);
                        }
                        /* fall through */
                case BLKIF_OP_READ:
@@ -1076,20 +1063,20 @@ static void blkfront_connect(struct blkfront_info *info)
        /*
         * If there's no "feature-barrier" defined, then it means
         * we're dealing with a very old backend which writes
-        * synchronously; draining will do what needs to get done.
+        * synchronously; nothing to do.
         *
-        * If there are barriers, then we can do full queued writes
-        * with tagged barriers.
-        *
-        * If barriers are not supported, then there's no much we can
-        * do, so just set ordering to NONE.
+        * If there are barriers, then we use flush.
         */
-       if (err)
-               info->feature_barrier = QUEUE_ORDERED_DRAIN;
-       else if (barrier)
-               info->feature_barrier = QUEUE_ORDERED_TAG;
-       else
-               info->feature_barrier = QUEUE_ORDERED_NONE;
+       info->feature_flush = 0;
+
+       /*
+        * The driver doesn't properly handled empty flushes, so
+        * lets disable barrier support for now.
+        */
+#if 0
+       if (!err && barrier)
+               info->feature_flush = REQ_FLUSH;
+#endif
 
        err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
        if (err) {
@@ -1203,7 +1190,7 @@ static int blkif_open(struct block_device *bdev, fmode_t mode)
        struct blkfront_info *info;
        int err = 0;
 
-       lock_kernel();
+       mutex_lock(&blkfront_mutex);
 
        info = disk->private_data;
        if (!info) {
@@ -1221,7 +1208,7 @@ static int blkif_open(struct block_device *bdev, fmode_t mode)
        mutex_unlock(&info->mutex);
 
 out:
-       unlock_kernel();
+       mutex_unlock(&blkfront_mutex);
        return err;
 }
 
@@ -1231,7 +1218,7 @@ static int blkif_release(struct gendisk *disk, fmode_t mode)
        struct block_device *bdev;
        struct xenbus_device *xbdev;
 
-       lock_kernel();
+       mutex_lock(&blkfront_mutex);
 
        bdev = bdget_disk(disk, 0);
        bdput(bdev);
@@ -1265,7 +1252,7 @@ static int blkif_release(struct gendisk *disk, fmode_t mode)
        }
 
 out:
-       unlock_kernel();
+       mutex_unlock(&blkfront_mutex);
        return 0;
 }