[PATCH] floppy: reintroduce O_NDELAY fix

Jiri Kosina
2021-01-22T11:21:21Z

From: Jiri Kosina <jkosina@suse.cz>

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.

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>
---
drivers/block/floppy.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)

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;

--
Jiri Kosina
SUSE Labs