bdev: use bdev_io_min() for statx block size

JIRA: https://issues.redhat.com/browse/RHEL-88002

commit 425fbcd
Author: Luis Chamberlain <mcgrof@kernel.org>
Date:   Fri Feb 21 14:38:23 2025 -0800

    bdev: use bdev_io_min() for statx block size

    You can use lsblk to query for a block device block device block size:

    lsblk -o MIN-IO /dev/nvme0n1
    MIN-IO
     4096

    The min-io is the minimum IO the block device prefers for optimal
    performance. In turn we map this to the block device block size.
    The current block size exposed even for block devices with an
    LBA format of 16k is 4k. Likewise devices which support 4k LBA format
    but have a larger Indirection Unit of 16k have an exposed block size
    of 4k.

    This incurs read-modify-writes on direct IO against devices with a
    min-io larger than the page size. To fix this, use the block device
    min io, which is the minimal optimal IO the device prefers.

    With this we now get:

    lsblk -o MIN-IO /dev/nvme0n1
    MIN-IO
     16384

    And so userspace gets the appropriate information it needs for optimal
    performance. This is verified with blkalgn against mkfs against a
    device with LBA format of 4k but an NPWG of 16k (min io size)

    mkfs.xfs -f -b size=16k  /dev/nvme3n1
    blkalgn -d nvme3n1 --ops Write

         Block size          : count     distribution
             0 -> 1          : 0        |                                        |
             2 -> 3          : 0        |                                        |
             4 -> 7          : 0        |                                        |
             8 -> 15         : 0        |                                        |
            16 -> 31         : 0        |                                        |
            32 -> 63         : 0        |                                        |
            64 -> 127        : 0        |                                        |
           128 -> 255        : 0        |                                        |
           256 -> 511        : 0        |                                        |
           512 -> 1023       : 0        |                                        |
          1024 -> 2047       : 0        |                                        |
          2048 -> 4095       : 0        |                                        |
          4096 -> 8191       : 0        |                                        |
          8192 -> 16383      : 0        |                                        |
         16384 -> 32767      : 66       |****************************************|
         32768 -> 65535      : 0        |                                        |
         65536 -> 131071     : 0        |                                        |
        131072 -> 262143     : 2        |*                                       |
    Block size: 14 - 66
    Block size: 17 - 2

         Algn size           : count     distribution
             0 -> 1          : 0        |                                        |
             2 -> 3          : 0        |                                        |
             4 -> 7          : 0        |                                        |
             8 -> 15         : 0        |                                        |
            16 -> 31         : 0        |                                        |
            32 -> 63         : 0        |                                        |
            64 -> 127        : 0        |                                        |
           128 -> 255        : 0        |                                        |
           256 -> 511        : 0        |                                        |
           512 -> 1023       : 0        |                                        |
          1024 -> 2047       : 0        |                                        |
          2048 -> 4095       : 0        |                                        |
          4096 -> 8191       : 0        |                                        |
          8192 -> 16383      : 0        |                                        |
         16384 -> 32767      : 66       |****************************************|
         32768 -> 65535      : 0        |                                        |
         65536 -> 131071     : 0        |                                        |
        131072 -> 262143     : 2        |*                                       |
    Algn size: 14 - 66
    Algn size: 17 - 2

    Reviewed-by: Hannes Reinecke <hare@suse.de>
    Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
    Link: https://lore.kernel.org/r/20250221223823.1680616-9-mcgrof@kernel.org
    Reviewed-by: John Garry <john.g.garry@oracle.com>
    Signed-off-by: Christian Brauner <brauner@kernel.org>

Signed-off-by: Ming Lei <ming.lei@redhat.com>

Author: Ming Lei

block/bdev.c

@@ -1246,9 +1246,6 @@ void bdev_statx(struct inode *backing_inode, struct kstat *stat,
 {
 	struct block_device *bdev;
 
-	if (!(request_mask & (STATX_DIOALIGN | STATX_WRITE_ATOMIC)))
-		return;
-
 	/*
 	 * Note that backing_inode is the inode of a block device node file,
 	 * not the block device's internal inode.  Therefore it is *not* valid
@@ -1273,6 +1270,8 @@ void bdev_statx(struct inode *backing_inode, struct kstat *stat,
 			queue_atomic_write_unit_max_bytes(bd_queue));
 	}
 
+	stat->blksize = bdev_io_min(bdev);
+
 	blkdev_put_no_open(bdev);
 }