[PATCH AUTOSEL 5.5 121/542] nbd: add a flush_workqueue in nbd_start_device

[PATCH AUTOSEL 5.5 121/542] nbd: add a flush_workqueue in nbd_start_device

[Sasha Levin]

From: Sun Ke <sunke32@huawei.com>

[ Upstream commit 5c0dd228b5fc30a3b732c7ae2657e0161ec7ed80 ]

When kzalloc fail, may cause trying to destroy the
workqueue from inside the workqueue.

If num_connections is m (2 < m), and NO.1 ~ NO.n
(1 < n < m) kzalloc are successful. The NO.(n + 1)
failed. Then, nbd_start_device will return ENOMEM
to nbd_start_device_ioctl, and nbd_start_device_ioctl
will return immediately without running flush_workqueue.
However, we still have n recv threads. If nbd_release
run first, recv threads may have to drop the last
config_refs and try to destroy the workqueue from
inside the workqueue.

To fix it, add a flush_workqueue in nbd_start_device.

Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs")
Signed-off-by: Sun Ke <sunke32@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/nbd.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index b4607dd961852..78181908f0df6 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1265,6 +1265,16 @@ static int nbd_start_device(struct nbd_device *nbd)
 		args = kzalloc(sizeof(*args), GFP_KERNEL);
 		if (!args) {
 			sock_shutdown(nbd);
+			/*
+			 * If num_connections is m (2 < m),
+			 * and NO.1 ~ NO.n(1 < n < m) kzallocs are successful.
+			 * But NO.(n + 1) failed. We still have n recv threads.
+			 * So, add flush_workqueue here to prevent recv threads
+			 * dropping the last config_refs and trying to destroy
+			 * the workqueue from inside the workqueue.
+			 */
+			if (i)
+				flush_workqueue(nbd->recv_workq);
 			return -ENOMEM;
 		}
 		sk_set_memalloc(config->socks[i]->sock->sk);
-- 
2.20.1

[PATCH AUTOSEL 5.5 124/542] drivers/block/zram/zram_drv.c: fix error return codes not being returned in writeback_store

[Sasha Levin]

From: Colin Ian King <colin.king@canonical.com>

[ Upstream commit 3b82a051c10143639a378dcd12019f2353cc9054 ]

Currently when an error code -EIO or -ENOSPC in the for-loop of
writeback_store the error code is being overwritten by a ret = len
assignment at the end of the function and the error codes are being
lost.  Fix this by assigning ret = len at the start of the function and
remove the assignment from the end, hence allowing ret to be preserved
when error codes are assigned to it.

Addresses Coverity ("Unused value")

Link: http://lkml.kernel.org/r/20191128122958.178290-1-colin.king@canonical.com
Fixes: a939888ec38b ("zram: support idle/huge page writeback")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/zram/zram_drv.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 4285e75e52c34..1bf4a908a0bd9 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -626,7 +626,7 @@ static ssize_t writeback_store(struct device *dev,
 	struct bio bio;
 	struct bio_vec bio_vec;
 	struct page *page;
-	ssize_t ret;
+	ssize_t ret = len;
 	int mode;
 	unsigned long blk_idx = 0;
 
@@ -762,7 +762,6 @@ static ssize_t writeback_store(struct device *dev,
 
 	if (blk_idx)
 		free_block_bdev(zram, blk_idx);
-	ret = len;
 	__free_page(page);
 release_init_lock:
 	up_read(&zram->init_lock);
-- 
2.20.1

[PATCH AUTOSEL 5.5 127/542] block, bfq: do not plug I/O for bfq_queues with no proc refs

[Sasha Levin]

From: Paolo Valente <paolo.valente@linaro.org>

[ Upstream commit f718b093277df582fbf8775548a4f163e664d282 ]

Commit 478de3380c1c ("block, bfq: deschedule empty bfq_queues not
referred by any process") fixed commit 3726112ec731 ("block, bfq:
re-schedule empty queues if they deserve I/O plugging") by
descheduling an empty bfq_queue when it remains with not process
reference. Yet, this still left a case uncovered: an empty bfq_queue
with not process reference that remains in service. This happens for
an in-service sync bfq_queue that is deemed to deserve I/O-dispatch
plugging when it remains empty. Yet no new requests will arrive for
such a bfq_queue if no process sends requests to it any longer. Even
worse, the bfq_queue may happen to be prematurely freed while still in
service (because there may remain no reference to it any longer).

This commit solves this problem by preventing I/O dispatch from being
plugged for the in-service bfq_queue, if the latter has no process
reference (the bfq_queue is then prevented from remaining in service).

Fixes: 3726112ec731 ("block, bfq: re-schedule empty queues if they deserve I/O plugging")
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Reported-by: Patrick Dung <patdung100@gmail.com>
Tested-by: Patrick Dung <patdung100@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 block/bfq-iosched.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index ad4af4aaf2ced..5c239c540c47a 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -3444,6 +3444,10 @@ static void bfq_dispatch_remove(struct request_queue *q, struct request *rq)
 static bool idling_needed_for_service_guarantees(struct bfq_data *bfqd,
 						 struct bfq_queue *bfqq)
 {
+	/* No point in idling for bfqq if it won't get requests any longer */
+	if (unlikely(!bfqq_process_refs(bfqq)))
+		return false;
+
 	return (bfqq->wr_coeff > 1 &&
 		(bfqd->wr_busy_queues <
 		 bfq_tot_busy_queues(bfqd) ||
@@ -4077,6 +4081,10 @@ static bool idling_boosts_thr_without_issues(struct bfq_data *bfqd,
 		bfqq_sequential_and_IO_bound,
 		idling_boosts_thr;
 
+	/* No point in idling for bfqq if it won't get requests any longer */
+	if (unlikely(!bfqq_process_refs(bfqq)))
+		return false;
+
 	bfqq_sequential_and_IO_bound = !BFQQ_SEEKY(bfqq) &&
 		bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_has_short_ttime(bfqq);
 
@@ -4170,6 +4178,10 @@ static bool bfq_better_to_idle(struct bfq_queue *bfqq)
 	struct bfq_data *bfqd = bfqq->bfqd;
 	bool idling_boosts_thr_with_no_issue, idling_needed_for_service_guar;
 
+	/* No point in idling for bfqq if it won't get requests any longer */
+	if (unlikely(!bfqq_process_refs(bfqq)))
+		return false;
+
 	if (unlikely(bfqd->strict_guarantees))
 		return true;
 
-- 
2.20.1

[PATCH AUTOSEL 5.5 488/542] rbd: work around -Wuninitialized warning

[Sasha Levin]

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit a55e601b2f02df5db7070e9a37bd655c9c576a52 ]

gcc -O3 warns about a dummy variable that is passed
down into rbd_img_fill_nodata without being initialized:

drivers/block/rbd.c: In function 'rbd_img_fill_nodata':
drivers/block/rbd.c:2573:13: error: 'dummy' is used uninitialized in this function [-Werror=uninitialized]
  fctx->iter = *fctx->pos;

Since this is a dummy, I assume the warning is harmless, but
it's better to initialize it anyway and avoid the warning.

Fixes: mmtom ("init/Kconfig: enable -O3 for all arches")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/rbd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 2b184563cd32e..38dcb39051a7f 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2662,7 +2662,7 @@ static int rbd_img_fill_nodata(struct rbd_img_request *img_req,
 			       u64 off, u64 len)
 {
 	struct ceph_file_extent ex = { off, len };
-	union rbd_img_fill_iter dummy;
+	union rbd_img_fill_iter dummy = {};
 	struct rbd_img_fill_ctx fctx = {
 		.pos_type = OBJ_REQUEST_NODATA,
 		.pos = &dummy,
-- 
2.20.1

[PATCH AUTOSEL 5.5 528/542] brd: check and limit max_part par

[Sasha Levin]

From: Zhiqiang Liu <liuzhiqiang26@huawei.com>

[ Upstream commit c8ab422553c81a0eb070329c63725df1cd1425bc ]

In brd_init func, rd_nr num of brd_device are firstly allocated
and add in brd_devices, then brd_devices are traversed to add each
brd_device by calling add_disk func. When allocating brd_device,
the disk->first_minor is set to i * max_part, if rd_nr * max_part
is larger than MINORMASK, two different brd_device may have the same
devt, then only one of them can be successfully added.
when rmmod brd.ko, it will cause oops when calling brd_exit.

Follow those steps:
  # modprobe brd rd_nr=3 rd_size=102400 max_part=1048576
  # rmmod brd
then, the oops will appear.

Oops log:
[  726.613722] Call trace:
[  726.614175]  kernfs_find_ns+0x24/0x130
[  726.614852]  kernfs_find_and_get_ns+0x44/0x68
[  726.615749]  sysfs_remove_group+0x38/0xb0
[  726.616520]  blk_trace_remove_sysfs+0x1c/0x28
[  726.617320]  blk_unregister_queue+0x98/0x100
[  726.618105]  del_gendisk+0x144/0x2b8
[  726.618759]  brd_exit+0x68/0x560 [brd]
[  726.619501]  __arm64_sys_delete_module+0x19c/0x2a0
[  726.620384]  el0_svc_common+0x78/0x130
[  726.621057]  el0_svc_handler+0x38/0x78
[  726.621738]  el0_svc+0x8/0xc
[  726.622259] Code: aa0203f6 aa0103f7 aa1e03e0 d503201f (7940e260)

Here, we add brd_check_and_reset_par func to check and limit max_part par.

--
V5->V6:
 - remove useless code

V4->V5:(suggested by Ming Lei)
 - make sure max_part is not larger than DISK_MAX_PARTS

V3->V4:(suggested by Ming Lei)
 - remove useless change
 - add one limit of max_part

V2->V3: (suggested by Ming Lei)
 - clear .minors when running out of consecutive minor space in brd_alloc
 - remove limit of rd_nr

V1->V2:
 - add more checks in brd_check_par_valid as suggested by Ming Lei.

Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/brd.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index a8730cc4db10e..220c5e18aba0c 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -473,6 +473,25 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data)
 	return kobj;
 }
 
+static inline void brd_check_and_reset_par(void)
+{
+	if (unlikely(!max_part))
+		max_part = 1;
+
+	/*
+	 * make sure 'max_part' can be divided exactly by (1U << MINORBITS),
+	 * otherwise, it is possiable to get same dev_t when adding partitions.
+	 */
+	if ((1U << MINORBITS) % max_part != 0)
+		max_part = 1UL << fls(max_part);
+
+	if (max_part > DISK_MAX_PARTS) {
+		pr_info("brd: max_part can't be larger than %d, reset max_part = %d.\n",
+			DISK_MAX_PARTS, DISK_MAX_PARTS);
+		max_part = DISK_MAX_PARTS;
+	}
+}
+
 static int __init brd_init(void)
 {
 	struct brd_device *brd, *next;
@@ -496,8 +515,7 @@ static int __init brd_init(void)
 	if (register_blkdev(RAMDISK_MAJOR, "ramdisk"))
 		return -EIO;
 
-	if (unlikely(!max_part))
-		max_part = 1;
+	brd_check_and_reset_par();
 
 	for (i = 0; i < rd_nr; i++) {
 		brd = brd_alloc(i);
-- 
2.20.1