Btrfs: Force stripesize to the value of sectorsize

Btrfs code currently assumes stripesize to be same as
sectorsize. However Btrfs-progs (until commit
df05c7ed455f519e6e15e46196392e4757257305) has been setting
btrfs_super_block->stripesize to a value of 4096.

This commit makes sure that the value of btrfs_super_block->stripesize
is a power of 2. Later, it unconditionally sets btrfs_root->stripesize
to sectorsize.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

fs/btrfs/disk-io.c

@@ -2806,7 +2806,7 @@ int open_ctree(struct super_block *sb,
 
 	nodesize = btrfs_super_nodesize(disk_super);
 	sectorsize = btrfs_super_sectorsize(disk_super);
-	stripesize = btrfs_super_stripesize(disk_super);
+	stripesize = sectorsize;
 	fs_info->dirty_metadata_batch = nodesize * (1 + ilog2(nr_cpu_ids));
 	fs_info->delalloc_batch = sectorsize * 512 * (1 + ilog2(nr_cpu_ids));
 
@@ -4133,9 +4133,7 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info,
 		       btrfs_super_bytes_used(sb));
 		ret = -EINVAL;
 	}
-	if (!is_power_of_2(btrfs_super_stripesize(sb)) ||
-		((btrfs_super_stripesize(sb) != sectorsize) &&
-			(btrfs_super_stripesize(sb) != 4096))) {
+	if (!is_power_of_2(btrfs_super_stripesize(sb))) {
 		btrfs_err(fs_info, "invalid stripesize %u",
 		       btrfs_super_stripesize(sb));
 		ret = -EINVAL;

fs/btrfs/volumes.c

@@ -4694,12 +4694,12 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 
 	if (type & BTRFS_BLOCK_GROUP_RAID5) {
 		raid_stripe_len = find_raid56_stripe_len(ndevs - 1,
-				 btrfs_super_stripesize(info->super_copy));
+						extent_root->stripesize);
 		data_stripes = num_stripes - 1;
 	}
 	if (type & BTRFS_BLOCK_GROUP_RAID6) {
 		raid_stripe_len = find_raid56_stripe_len(ndevs - 2,
-				 btrfs_super_stripesize(info->super_copy));
+						extent_root->stripesize);
 		data_stripes = num_stripes - 2;
 	}