md: do not return existing mddevs from mddev_find_or_alloc

Instead of returning an existing mddev, just for it to be discarded
later directly return -EEXIST.  Rename the function to mddev_alloc now
that it doesn't find an existing mddev.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index de6f8e5..af9bdb9 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -782,26 +782,24 @@ static struct mddev *mddev_find(dev_t unit)
        return mddev;
 }
 
-static struct mddev *mddev_find_or_alloc(dev_t unit)
+static struct mddev *mddev_alloc(dev_t unit)
 {
-       struct mddev *mddev = NULL, *new;
+       struct mddev *new;
+       int error;
 
        if (unit && MAJOR(unit) != MD_MAJOR)
                unit &= ~((1 << MdpMinorShift) - 1);
 
        new = kzalloc(sizeof(*new), GFP_KERNEL);
        if (!new)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
        mddev_init(new);
 
        spin_lock(&all_mddevs_lock);
        if (unit) {
-               mddev = mddev_find_locked(unit);
-               if (mddev) {
-                       mddev_get(mddev);
+               error = -EEXIST;
+               if (mddev_find_locked(unit))
                        goto out_free_new;
-               }
-
                new->unit = unit;
                if (MAJOR(unit) == MD_MAJOR)
                        new->md_minor = MINOR(unit);
@@ -809,6 +807,7 @@ static struct mddev *mddev_find_or_alloc(dev_t unit)
                        new->md_minor = MINOR(unit) >> MdpMinorShift;
                new->hold_active = UNTIL_IOCTL;
        } else {
+               error = -ENODEV;
                new->unit = mddev_alloc_unit();
                if (!new->unit)
                        goto out_free_new;
@@ -822,7 +821,7 @@ static struct mddev *mddev_find_or_alloc(dev_t unit)
 out_free_new:
        spin_unlock(&all_mddevs_lock);
        kfree(new);
-       return mddev;
+       return ERR_PTR(error);
 }
 
 static struct attribute_group md_redundancy_group;
@@ -5661,29 +5660,29 @@ static int md_alloc(dev_t dev, char *name)
         * writing to /sys/module/md_mod/parameters/new_array.
         */
        static DEFINE_MUTEX(disks_mutex);
-       struct mddev *mddev = mddev_find_or_alloc(dev);
+       struct mddev *mddev;
        struct gendisk *disk;
        int partitioned;
        int shift;
        int unit;
-       int error;
-
-       if (!mddev)
-               return -ENODEV;
+       int error ;
 
-       partitioned = (MAJOR(mddev->unit) != MD_MAJOR);
-       shift = partitioned ? MdpMinorShift : 0;
-       unit = MINOR(mddev->unit) >> shift;
-
-       /* wait for any previous instance of this device to be
-        * completely removed (mddev_delayed_delete).
+       /*
+        * Wait for any previous instance of this device to be completely
+        * removed (mddev_delayed_delete).
         */
        flush_workqueue(md_misc_wq);
 
        mutex_lock(&disks_mutex);
-       error = -EEXIST;
-       if (mddev->gendisk)
-               goto abort;
+       mddev = mddev_alloc(dev);
+       if (IS_ERR(mddev)) {
+               mutex_unlock(&disks_mutex);
+               return PTR_ERR(mddev);
+       }
+
+       partitioned = (MAJOR(mddev->unit) != MD_MAJOR);
+       shift = partitioned ? MdpMinorShift : 0;
+       unit = MINOR(mddev->unit) >> shift;
 
        if (name && !dev) {
                /* Need to ensure that 'name' is not a duplicate.
@@ -5695,6 +5694,7 @@ static int md_alloc(dev_t dev, char *name)
                        if (mddev2->gendisk &&
                            strcmp(mddev2->gendisk->disk_name, name) == 0) {
                                spin_unlock(&all_mddevs_lock);
+                               error = -EEXIST;
                                goto abort;
                        }
                spin_unlock(&all_mddevs_lock);