dm table: ensure targets are aligned to logical_block_size

Ensure I/O is aligned to the logical block size of target devices.

Rename check_device_area() to device_area_is_valid() for clarity and
establish the device limits including the logical block size prior to
calling it.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index af1ceae..535fdaf 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -383,16 +383,45 @@ static void close_dev(struct dm_dev_internal *d, struct mapped_device *md)
 /*
  * If possible, this checks an area of a destination device is valid.
  */
-static int check_device_area(struct dm_dev_internal *dd, sector_t start,
-                            sector_t len)
+static int device_area_is_valid(struct dm_target *ti, struct block_device *bdev,
+                            sector_t start, sector_t len)
 {
-       sector_t dev_size = i_size_read(dd->dm_dev.bdev->bd_inode) >>
-                           SECTOR_SHIFT;
+       sector_t dev_size = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
+       unsigned short logical_block_size_sectors =
+               ti->limits.logical_block_size >> SECTOR_SHIFT;
+       char b[BDEVNAME_SIZE];
 
        if (!dev_size)
                return 1;
 
-       return ((start < dev_size) && (len <= (dev_size - start)));
+       if ((start >= dev_size) || (start + len > dev_size)) {
+               DMWARN("%s: %s too small for target",
+                      dm_device_name(ti->table->md), bdevname(bdev, b));
+               return 0;
+       }
+
+       if (logical_block_size_sectors <= 1)
+               return 1;
+
+       if (start & (logical_block_size_sectors - 1)) {
+               DMWARN("%s: start=%llu not aligned to h/w "
+                      "logical block size %hu of %s",
+                      dm_device_name(ti->table->md),
+                      (unsigned long long)start,
+                      ti->limits.logical_block_size, bdevname(bdev, b));
+               return 0;
+       }
+
+       if (len & (logical_block_size_sectors - 1)) {
+               DMWARN("%s: len=%llu not aligned to h/w "
+                      "logical block size %hu of %s",
+                      dm_device_name(ti->table->md),
+                      (unsigned long long)len,
+                      ti->limits.logical_block_size, bdevname(bdev, b));
+               return 0;
+       }
+
+       return 1;
 }
 
 /*
@@ -478,14 +507,7 @@ static int __table_get_device(struct dm_table *t, struct dm_target *ti,
        }
        atomic_inc(&dd->count);
 
-       if (!check_device_area(dd, start, len)) {
-               DMWARN("device %s too small for target", path);
-               dm_put_device(ti, &dd->dm_dev);
-               return -EINVAL;
-       }
-
        *result = &dd->dm_dev;
-
        return 0;
 }
 
@@ -554,8 +576,16 @@ int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
        int r = __table_get_device(ti->table, ti, path,
                                   start, len, mode, result);
 
-       if (!r)
-               dm_set_device_limits(ti, (*result)->bdev);
+       if (r)
+               return r;
+
+       dm_set_device_limits(ti, (*result)->bdev);
+
+       if (!device_area_is_valid(ti, (*result)->bdev, start, len)) {
+               dm_put_device(ti, *result);
+               *result = NULL;
+               return -EINVAL;
+       }
 
        return r;
 }