On 1/26/21 12:31 PM, Kurt Garloff wrote:

Hi Denis, Jiri, Jens,

Am 26.01.21 um 09:21 schrieb Denis Efremov:

quoted

On 1/22/21 2:13 PM, Jiri Kosina wrote:

quoted

From: Jiri Kosina <redacted>

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 <redacted>
Tested-by: Wim Osterholt <redacted>
Reported-and-tested-by: Kurt Garloff <redacted>
Fixes: 09954bad4 ("floppy: refactor open() flags handling")
Fixes: f2791e7ead ("Revert "floppy: refactor open() flags handling"")
Signed-off-by: Jiri Kosina <redacted>

Applied. I'll send it to Jens soon with a couple of cleanup patches.

https://github.com/evdenis/linux-floppy/commit/e32f6163c47efbdbad06258560aa00d1c7e5b699

Great, thanks.

Due to libblkid (rightfully) using O_NONBLOCK these days when probing
devices, the floppy driver does spit loads of
[    9.533513] floppy0: disk absent or changed during operation
[    9.534989] blk_update_request: I/O error, dev fd0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[    9.537206] Buffer I/O error on dev fd0, logical block 0, async page read
[    9.546837] floppy0: disk absent or changed during operation
[    9.548389] blk_update_request: I/O error, dev fd0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1
and fails a mount prior to being opened without O_NONBLOCK at least once.
(Reproduction is easy with qemu-kvm.)

The patch addresses it and I would suggest it to also be backported and
applied to the active stable kernel trees.

Yes, it will be backported to all stable trees including v4.4

Thanks,
Denis