From ed480f2b9e86102b5d57fcd708915ae4f34add5b Mon Sep 17 00:00:00 2001 From: "Maciej S. Szmigiero" Date: Wed, 15 Aug 2018 23:56:45 +0200 Subject: [PATCH] block, bfq: return nbytes and not zero from struct cftype .write() method commit fc8ebd01deeb12728c83381f6ec923e4a192ffd3 upstream. The value that struct cftype .write() method returns is then directly returned to userspace as the value returned by write() syscall, so it should be the number of bytes actually written (or consumed) and not zero. Returning zero from write() syscall makes programs like /bin/echo or bash spin. Signed-off-by: Maciej S. Szmigiero Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/bfq-cgroup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 5d53e50..4b571f3 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -887,7 +887,8 @@ static ssize_t bfq_io_set_weight(struct kernfs_open_file *of, if (ret) return ret; - return bfq_io_set_weight_legacy(of_css(of), NULL, weight); + ret = bfq_io_set_weight_legacy(of_css(of), NULL, weight); + return ret ?: nbytes; } static int bfqg_print_stat(struct seq_file *sf, void *v) -- 2.7.4