[PATCH RESEND] floppy: fix open(O_ACCMODE) for ioctl-only open

[Jiri Kosina]

From: Jiri Kosina <jkos...@suse.cz>

Commit 09954bad4 ("floppy: refactor open() flags handling"), as a 
side-effect, causes open(/dev/fdX, O_ACCMODE) to fail. It turns out that 
this is being used setfdprm userspace for ioctl-only open().

Reintroduce back the original behavior wrt !(FMODE_READ|FMODE_WRITE) 
modes, while still keeping the original O_NDELAY bug fixed.

Cc: sta...@vger.kernel.org # v4.5+
Reported-by: Wim Osterholt <w...@djo.tudelft.nl>
Tested-by: Wim Osterholt <w...@djo.tudelft.nl>
Signed-off-by: Jiri Kosina <jkos...@suse.cz>
---

Jens, this should preferably go into 4.7-rcX and to -stable as well.

 drivers/block/floppy.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 84708a5..a1dcf12 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3663,11 +3663,6 @@ static int floppy_open(struct block_device *bdev, 
fmode_t mode)
 
        opened_bdev[drive] = bdev;
 
-       if (!(mode & (FMODE_READ|FMODE_WRITE))) {
-               res = -EINVAL;
-               goto out;
-       }
-
        res = -ENXIO;
 
        if (!floppy_track_buffer) {
@@ -3711,13 +3706,15 @@ static int floppy_open(struct block_device *bdev, 
fmode_t mode)
        if (UFDCS->rawcmd == 1)
                UFDCS->rawcmd = 2;
 
-       UDRS->last_checked = 0;
-       clear_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags);
-       check_disk_change(bdev);
-       if (test_bit(FD_DISK_CHANGED_BIT, &UDRS->flags))
-               goto out;
-       if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags))
-               goto out;
+       if (mode & (FMODE_READ|FMODE_WRITE)) {
+               UDRS->last_checked = 0;
+               clear_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags);
+               check_disk_change(bdev);
+               if (test_bit(FD_DISK_CHANGED_BIT, &UDRS->flags))
+                       goto out;
+               if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags))
+                       goto out;
+       }
 
        res = -EROFS;
 
-- 
Jiri Kosina
SUSE Labs