[PATCH AUTOSEL 4.14 159/170] block/swim3: Fix -EBUSY error when re-opening device after unmount

Sasha Levin
2019-01-28T16:19:13Z

From: Finn Thain <fthain@telegraphics.com.au>

[ Upstream commit 296dcc40f2f2e402facf7cd26cf3f2c8f4b17d47 ]

When the block device is opened with FMODE_EXCL, ref_count is set to -1.
This value doesn't get reset when the device is closed which means the
device cannot be opened again. Fix this by checking for refcount <= 0
in the release method.

Reported-and-tested-by: Stan Johnson <userm57@yahoo.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/swim3.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/block/swim3.c b/drivers/block/swim3.c
index 0d7527c6825a..2f7acdb830c3 100644
--- a/drivers/block/swim3.c
+++ b/drivers/block/swim3.c
@@ -1027,7 +1027,11 @@ static void floppy_release(struct gendisk *disk, fmode_t mode)
struct swim3 __iomem *sw = fs->swim3;

mutex_lock(&swim3_mutex);
- if (fs->ref_count > 0 && --fs->ref_count == 0) {
+ if (fs->ref_count > 0)
+ --fs->ref_count;
+ else if (fs->ref_count == -1)
+ fs->ref_count = 0;
+ if (fs->ref_count == 0) {
swim3_action(fs, MOTOR_OFF);
out_8(&sw->control_bic, 0xff);
swim3_select(fs, RELAX);
--
2.19.1