[PATCH 6.12 162/567] floppy: fix for PAGE_SIZE != 4KB

Greg Kroah-Hartman
2026-01-06T17:23:14Z

From: Rene Rebe <rene@exactco.de>

commit 82d20481024cbae2ea87fe8b86d12961bfda7169 upstream.

For years I wondered why the floppy driver does not just work on
sparc64, e.g:

root@SUNW_375_0066:# disktype /dev/fd0
disktype: Can't open /dev/fd0: No such device or address

[ 525.341906] disktype: attempt to access beyond end of device
fd0: rw=0, sector=0, nr_sectors = 16 limit=8
[ 525.341991] floppy: error 10 while reading block 0

Turns out floppy.c __floppy_read_block_0 tries to read one page for
the first test read to determine the disk size and thus fails if that
is greater than 4k. Adjust minimum MAX_DISK_SIZE to PAGE_SIZE to fix
floppy on sparc64 and likely all other PAGE_SIZE != 4KB configs.

Cc: stable@vger.kernel.org
Signed-off-by: René Rebe <rene@exactco.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/block/floppy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -331,7 +331,7 @@ static bool initialized;
* This default is used whenever the current disk size is unknown.
* [Now it is rather a minimum]
*/
-#define MAX_DISK_SIZE 4 /* 3984 */
+#define MAX_DISK_SIZE (PAGE_SIZE / 1024)

/*
* globals used by 'result()'