From 9ae7e5a1cd17b271e1b3339a23883d3d64724dcc Mon Sep 17 00:00:00 2001 From: Mateusz Guzik Date: Wed, 19 Mar 2025 13:49:23 +0100 Subject: [PATCH] fs: predict not reaching the limit in alloc_empty_file() Eliminates a jump over a call to capable() in the common case. By default the limit is not even set, in which case the check can't even fail to begin with. It remains unset at least on Debian and Ubuntu. For this cases this can probably become a static branch instead. In the meantime tidy it up. I note the check separate from the bump makes the entire thing racy. Signed-off-by: Mateusz Guzik Link: https://lore.kernel.org/r/20250319124923.1838719-1-mjguzik@gmail.com Signed-off-by: Christian Brauner --- fs/file_table.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/file_table.c b/fs/file_table.c index f0291a66f9db4..4d9f723350fb5 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -216,7 +216,8 @@ struct file *alloc_empty_file(int flags, const struct cred *cred) /* * Privileged users can go above max_files */ - if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) { + if (unlikely(get_nr_files() >= files_stat.max_files) && + !capable(CAP_SYS_ADMIN)) { /* * percpu_counters are inaccurate. Do an expensive check before * we go and fail. -- 2.50.1