From 43c9835b144c7ce29efe142d662529662a9eb376 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 7 Jul 2023 11:42:39 +0200 Subject: block: don't allow enabling a cache on devices that don't support it 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 Link: https://lore.kernel.org/r/20230707094239.107968-3-hch@lst.de Signed-off-by: Jens Axboe --- block/blk-sysfs.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'block/blk-sysfs.c') diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 0cde6598fb2f..63e481262336 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -449,13 +449,16 @@ 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; } -- cgit v1.2.3