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From:   Denis Efremov <efremov@linux.com>
To:     linux-block@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, regressions@lists.linux.dev,
        Denis Efremov <efremov@linux.com>,
        Mark Hounschell <markh@compro.net>,
        Jiri Kosina <jkosina@suse.cz>,
        Wim Osterholt <wim@djo.tudelft.nl>,
        Kurt Garloff <kurt@garloff.de>, stable@vger.kernel.org
Subject: [PATCH] Revert "floppy: reintroduce O_NDELAY fix"
Date:   Sun,  8 Aug 2021 10:42:46 +0300
Message-Id: <20210808074246.33449-1-efremov@linux.com>
In-Reply-To: <de10cb47-34d1-5a88-7751-225ca380f735@compro.net>
References: <de10cb47-34d1-5a88-7751-225ca380f735@compro.net>
MIME-Version: 1.0
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The patch breaks userspace implementations (e.g. fdutils) and introduces
regressions in behaviour. Previously, it was possible to O_NDELAY open a
floppy device with no media inserted or with write protected media without
an error. Some userspace tools use this particular behavior for probing.

It's not the first time when we revert this patch. Previous revert is in
commit f2791e7eadf4 (Revert "floppy: refactor open() flags handling").

This reverts commit 8a0c014cd20516ade9654fc13b51345ec58e7be8.

Link: https://lore.kernel.org/linux-block/de10cb47-34d1-5a88-7751-225ca380f735@compro.net/
Reported-by: Mark Hounschell <markh@compro.net>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Wim Osterholt <wim@djo.tudelft.nl>
Cc: Kurt Garloff <kurt@garloff.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Denis Efremov <efremov@linux.com>
---
 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 87460e0e5c72..fef79ea52e3e 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4029,23 +4029,23 @@ 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_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))
+	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))
 			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;
-- 
2.31.1