6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christoph Hellwig <hch@xxxxxx>
[ Upstream commit 43c9835b144c7ce29efe142d662529662a9eb376 ]
Currently the write_cache attribute allows enabling the QUEUE_FLAG_WC
flag on devices that never claimed the capability.
Fix that by adding a QUEUE_FLAG_HW_WC flag that is set by
blk_queue_write_cache and guards re-enabling the cache through sysfs.
Note that any rescan that calls blk_queue_write_cache will still
re-enable the write cache as in the current code.
Fixes: 93e9d8e836cb ("block: add ability to flag write back caching on a device")
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/20230707094239.107968-3-hch@xxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
block/blk-settings.c | 7 +++++--
block/blk-sysfs.c | 11 +++++++----
include/linux/blkdev.h | 1 +
3 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 291cf9df7fc29..86ff375c00ce4 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -824,10 +824,13 @@ EXPORT_SYMBOL(blk_set_queue_depth);
*/
void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua)
{
- if (wc)
+ if (wc) {
+ blk_queue_flag_set(QUEUE_FLAG_HW_WC, q);
blk_queue_flag_set(QUEUE_FLAG_WC, q);
- else
+ } else {
+ blk_queue_flag_clear(QUEUE_FLAG_HW_WC, q);
blk_queue_flag_clear(QUEUE_FLAG_WC, q);
+ }
if (fua)
blk_queue_flag_set(QUEUE_FLAG_FUA, q);
else
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 4f34525bafac7..a582ea0da74f5 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -528,13 +528,16 @@ static ssize_t queue_wc_show(struct request_queue *q, char *page)
static ssize_t queue_wc_store(struct request_queue *q, const char *page,
size_t count)
{
- if (!strncmp(page, "write back", 10))
+ if (!strncmp(page, "write back", 10)) {
+ if (!test_bit(QUEUE_FLAG_HW_WC, &q->queue_flags))
+ return -EINVAL;
blk_queue_flag_set(QUEUE_FLAG_WC, q);
- else if (!strncmp(page, "write through", 13) ||
- !strncmp(page, "none", 4))
+ } else if (!strncmp(page, "write through", 13) ||
+ !strncmp(page, "none", 4)) {
blk_queue_flag_clear(QUEUE_FLAG_WC, q);
- else
+ } else {
return -EINVAL;
+ }
return count;
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 427e79ac72194..57674b3c58774 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -565,6 +565,7 @@ struct request_queue {
#define QUEUE_FLAG_NOXMERGES 9 /* No extended merges */
#define QUEUE_FLAG_ADD_RANDOM 10 /* Contributes to random pool */
#define QUEUE_FLAG_SAME_FORCE 12 /* force complete on same CPU */
+#define QUEUE_FLAG_HW_WC 18 /* Write back caching supported */
#define QUEUE_FLAG_INIT_DONE 14 /* queue is initialized */
#define QUEUE_FLAG_STABLE_WRITES 15 /* don't modify blks until WB is done */
#define QUEUE_FLAG_POLL 16 /* IO polling enabled if set */
--
2.40.1
