block: introduce partition 0

[mirror_ubuntu-bionic-kernel.git] / block / genhd.c

diff --git a/block/genhd.c b/block/genhd.c
index 0a2f16bd54b765b5c9f21a1d78a2923a78a80344..65b7386c26d8b561402e0d4dbd97597a3cf736a7 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -54,10 +54,10 @@ struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
 {
        struct hd_struct *part;
 
-       if (unlikely(partno < 1 || partno > disk_max_parts(disk)))
+       if (unlikely(partno < 0 || partno >= disk_max_parts(disk)))
                return NULL;
        rcu_read_lock();
-       part = rcu_dereference(disk->__part[partno - 1]);
+       part = rcu_dereference(disk->__part[partno]);
        if (part)
                get_device(part_to_dev(part));
        rcu_read_unlock();
@@ -85,8 +85,10 @@ void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 
        if (flags & DISK_PITER_REVERSE)
                piter->idx = disk_max_parts(piter->disk) - 1;
-       else
+       else if (flags & DISK_PITER_INCL_PART0)
                piter->idx = 0;
+       else
+               piter->idx = 1;
 
        piter->flags = flags;
 }
@@ -114,7 +116,10 @@ struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
        /* determine iteration parameters */
        if (piter->flags & DISK_PITER_REVERSE) {
                inc = -1;
-               end = -1;
+               if (piter->flags & DISK_PITER_INCL_PART0)
+                       end = -1;
+               else
+                       end = 0;
        } else {
                inc = 1;
                end = disk_max_parts(piter->disk);
@@ -177,7 +182,7 @@ struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
 {
        int i;
 
-       for (i = 0; i < disk_max_parts(disk); i++) {
+       for (i = 1; i < disk_max_parts(disk); i++) {
                struct hd_struct *part = rcu_dereference(disk->__part[i]);
 
                if (part && part->start_sect <= sector &&
@@ -669,7 +674,7 @@ static int show_partition(struct seq_file *seqf, void *v)
        char buf[BDEVNAME_SIZE];
 
        /* Don't show non-partitionable removeable devices or empty devices */
-       if (!get_capacity(sgp) || (!disk_max_parts(sgp) &&
+       if (!get_capacity(sgp) || (!disk_partitionable(sgp) &&
                                   (sgp->flags & GENHD_FL_REMOVABLE)))
                return 0;
        if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
@@ -742,7 +747,7 @@ static ssize_t disk_ext_range_show(struct device *dev,
 {
        struct gendisk *disk = dev_to_disk(dev);
 
-       return sprintf(buf, "%d\n", disk_max_parts(disk) + 1);
+       return sprintf(buf, "%d\n", disk_max_parts(disk));
 }
 
 static ssize_t disk_removable_show(struct device *dev,
@@ -998,7 +1003,7 @@ dev_t blk_lookup_devt(const char *name, int partno)
 
                if (strcmp(dev->bus_id, name))
                        continue;
-               if (partno < 0 || partno > disk_max_parts(disk))
+               if (partno < 0 || partno >= disk_max_parts(disk))
                        continue;
 
                if (partno == 0)
@@ -1045,21 +1050,22 @@ struct gendisk *alloc_disk_ext_node(int minors, int ext_minors, int node_id)
                                GFP_KERNEL | __GFP_ZERO, node_id);
        if (disk) {
                int tot_minors = minors + ext_minors;
+               int size = tot_minors * sizeof(struct hd_struct *);
 
                if (!init_disk_stats(disk)) {
                        kfree(disk);
                        return NULL;
                }
-               if (tot_minors > 1) {
-                       int size = (tot_minors - 1) * sizeof(struct hd_struct *);
-                       disk->__part = kmalloc_node(size,
-                               GFP_KERNEL | __GFP_ZERO, node_id);
-                       if (!disk->__part) {
-                               free_disk_stats(disk);
-                               kfree(disk);
-                               return NULL;
-                       }
+
+               disk->__part = kmalloc_node(size, GFP_KERNEL | __GFP_ZERO,
+                                           node_id);
+               if (!disk->__part) {
+                       free_disk_stats(disk);
+                       kfree(disk);
+                       return NULL;
                }
+               disk->__part[0] = &disk->part0;
+
                disk->minors = minors;
                disk->ext_minors = ext_minors;
                rand_initialize_disk(disk);