The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8a0c014cd20516ade9654fc13b51345ec58e7be8 Mon Sep 17 00:00:00 2001

From: Jiri Kosina jkosina@suse.cz Date: Fri, 22 Jan 2021 12:13:20 +0100 Subject: [PATCH] floppy: reintroduce O_NDELAY fix

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

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index dfe1dfc901cc..0b71292d9d5a 100644 --- 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;