floppy: reintroduce O_NDELAY fix

commit 8a0c014cd20516ade9654fc13b51345ec58e7be8 upstream.

This issue was originally fixed in 09954bad4 ("floppy: refactor open()
flags handling").

The fix as a side-effect, however, introduce issue for open(O_ACCMODE)
that is being used for ioctl-only open. I wrote a fix for that, but
instead of it being merged, full revert of 09954bad4 was performed,
re-introducing the O_NDELAY / O_NONBLOCK issue, and it strikes again.

This is a forward-port of the original fix to current codebase; the
original submission had the changelog below:

====
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.

Link: https://lore.kernel.org/r/nycvar.YFH.7.76.2101221209060.5622@cbobk.fhfr.pm
Cc: stable@vger.kernel.org
Reported-by: Wim Osterholt <wim@djo.tudelft.nl>
Tested-by: Wim Osterholt <wim@djo.tudelft.nl>
Reported-and-tested-by: Kurt Garloff <kurt@garloff.de>
Fixes: 09954bad4 ("floppy: refactor open() flags handling")
Fixes: f2791e7ead ("Revert "floppy: refactor open() flags handling"")
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index dfe1dfc901ccc2ae5876437f735220d1e1b6d41f..0b71292d9d5abdb659bba48301087b10887c9035 100644 (file)
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4121,23 +4121,23 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
        if (fdc_state[FDC(drive)].rawcmd == 1)
                fdc_state[FDC(drive)].rawcmd = 2;
 
-       if (!(mode & FMODE_NDELAY)) {
-               if (mode & (FMODE_READ|FMODE_WRITE)) {
-                       drive_state[drive].last_checked = 0;
-                       clear_bit(FD_OPEN_SHOULD_FAIL_BIT,
-                                 &drive_state[drive].flags);
-                       if (bdev_check_media_change(bdev))
-                               floppy_revalidate(bdev->bd_disk);
-                       if (test_bit(FD_DISK_CHANGED_BIT, &drive_state[drive].flags))
-                               goto out;
-                       if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &drive_state[drive].flags))
-                               goto out;
-               }
-               res = -EROFS;
-               if ((mode & FMODE_WRITE) &&
-                   !test_bit(FD_DISK_WRITABLE_BIT, &drive_state[drive].flags))
+       if (mode & (FMODE_READ|FMODE_WRITE)) {
+               drive_state[drive].last_checked = 0;
+               clear_bit(FD_OPEN_SHOULD_FAIL_BIT, &drive_state[drive].flags);
+               if (bdev_check_media_change(bdev))
+                       floppy_revalidate(bdev->bd_disk);
+               if (test_bit(FD_DISK_CHANGED_BIT, &drive_state[drive].flags))
+                       goto out;
+               if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &drive_state[drive].flags))
                        goto out;
        }
+
+       res = -EROFS;
+
+       if ((mode & FMODE_WRITE) &&
+                       !test_bit(FD_DISK_WRITABLE_BIT, &drive_state[drive].flags))
+               goto out;
+
        mutex_unlock(&open_lock);
        mutex_unlock(&floppy_mutex);
        return 0;