[SCSI] scsi_debug: fix logical block provisioning support

provisioning map (map_storep) is a bitmap accessed by bitops.

So the allocation size should be a multiple of sizeof(unsigned long) and
also the bitmap should be cleared by using bitmap_clear() instead of
memset().

Otherwise it will cause problem on big-endian architecture if the number of
bits is not a multiple of BITS_PER_LONG.

I tried testing the logical block provisioning support in scsi_debug,
but it didn't work as I expected.

For example, load scsi_debug module with UNMAP command supported
and fill the storage with random data.

        # modprobe scsi_debug lbpu=1
        # dd if=/dev/urandom of=/dev/sdb

Then, try to unmap LBA 0, but Get LBA status reports:

        # sg_unmap --lba=0 --num=1 /dev/sdb
        # sg_get_lba_status --lba=0 /dev/sdb
        descriptor LBA: 0x0000000000000000  blocks: 16384  mapped

This is unexpected result.  Because UNMAP command to LBA 0 finished
without any errors, but Get LBA status shows that LBA 0 is still mapped.

This problem is due to the wrong translation between LBA and index of
provisioning map.  Fix it by using correct translation functions.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 41 insertions, 40 deletions

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 4b5d3887ff47..154d9870dc5a 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -1997,24 +1997,39 @@ out:
         return ret;
 }
 
-static unsigned int map_state(sector_t lba, unsigned int *num)
+static unsigned long lba_to_map_index(sector_t lba)
+{
+        if (scsi_debug_unmap_alignment) {
+                lba += scsi_debug_unmap_granularity -
+                        scsi_debug_unmap_alignment;
+        }
+        do_div(lba, scsi_debug_unmap_granularity);
+
+        return lba;
+}
+
+static sector_t map_index_to_lba(unsigned long index)
 {
-        unsigned int granularity, alignment, mapped;
-        sector_t block, next, end;
+        return index * scsi_debug_unmap_granularity -
+                scsi_debug_unmap_alignment;
+}
 
-        granularity = scsi_debug_unmap_granularity;
-        alignment = granularity - scsi_debug_unmap_alignment;
-        block = lba + alignment;
-        do_div(block, granularity);
+static unsigned int map_state(sector_t lba, unsigned int *num)
+{
+        sector_t end;
+        unsigned int mapped;
+        unsigned long index;
+        unsigned long next;
 
-        mapped = test_bit(block, map_storep);
+        index = lba_to_map_index(lba);
+        mapped = test_bit(index, map_storep);
 
         if (mapped)
-                next = find_next_zero_bit(map_storep, map_size, block);
+                next = find_next_zero_bit(map_storep, map_size, index);
         else
-                next = find_next_bit(map_storep, map_size, block);
+                next = find_next_bit(map_storep, map_size, index);
 
-        end = next * granularity - scsi_debug_unmap_alignment;
+        end = min_t(sector_t, sdebug_store_sectors,  map_index_to_lba(next));
         *num = end - lba;
 
         return mapped;
@@ -2022,48 +2037,37 @@ static unsigned int map_state(sector_t lba, unsigned int *num)
 
 static void map_region(sector_t lba, unsigned int len)
 {
-        unsigned int granularity, alignment;
         sector_t end = lba + len;
 
-        granularity = scsi_debug_unmap_granularity;
-        alignment = granularity - scsi_debug_unmap_alignment;
-
         while (lba < end) {
-                sector_t block, rem;
-
-                block = lba + alignment;
-                rem = do_div(block, granularity);
+                unsigned long index = lba_to_map_index(lba);
 
-                if (block < map_size)
-                        set_bit(block, map_storep);
+                if (index < map_size)
+                        set_bit(index, map_storep);
 
-                lba += granularity - rem;
+                lba = map_index_to_lba(index + 1);
         }
 }
 
 static void unmap_region(sector_t lba, unsigned int len)
 {
-        unsigned int granularity, alignment;
         sector_t end = lba + len;
 
-        granularity = scsi_debug_unmap_granularity;
-        alignment = granularity - scsi_debug_unmap_alignment;
-
         while (lba < end) {
-                sector_t block, rem;
-
-                block = lba + alignment;
-                rem = do_div(block, granularity);
+                unsigned long index = lba_to_map_index(lba);
 
-                if (rem == 0 && lba + granularity < end && block < map_size) {
-                        clear_bit(block, map_storep);
-                        if (scsi_debug_lbprz)
+                if (lba == map_index_to_lba(index) &&
+                    lba + scsi_debug_unmap_granularity <= end &&
+                    index < map_size) {
+                        clear_bit(index, map_storep);
+                        if (scsi_debug_lbprz) {
                                 memset(fake_storep +
                                        lba * scsi_debug_sector_size, 0,
                                        scsi_debug_sector_size *
                                        scsi_debug_unmap_granularity);
+                        }
                 }
-                lba += granularity - rem;
+                lba = map_index_to_lba(index + 1);
         }
 }
 
@@ -3402,8 +3406,6 @@ static int __init scsi_debug_init(void)
 
         /* Logical Block Provisioning */
         if (scsi_debug_lbp()) {
-                unsigned int map_bytes;
-
                 scsi_debug_unmap_max_blocks =
                         clamp(scsi_debug_unmap_max_blocks, 0U, 0xffffffffU);
 
@@ -3422,9 +3424,8 @@ static int __init scsi_debug_init(void)
                         return -EINVAL;
                 }
 
-                map_size = (sdebug_store_sectors / scsi_debug_unmap_granularity);
-                map_bytes = map_size >> 3;
-                map_storep = vmalloc(map_bytes);
+                map_size = lba_to_map_index(sdebug_store_sectors - 1) + 1;
+                map_storep = vmalloc(BITS_TO_LONGS(map_size) * sizeof(long));
 
                 printk(KERN_INFO "scsi_debug_init: %lu provisioning blocks\n",
                        map_size);
@@ -3435,7 +3436,7 @@ static int __init scsi_debug_init(void)
                         goto free_vm;
                 }
 
-                memset(map_storep, 0x0, map_bytes);
+                bitmap_zero(map_storep, map_size);
 
                 /* Map first 1KB for partition table */
                 if (scsi_debug_num_parts)