Unverified Commit 9ae7e5a1 authored by Mateusz Guzik's avatar Mateusz Guzik Committed by Christian Brauner
Browse files

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: default avatarMateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250319124923.1838719-1-mjguzik@gmail.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 5a607aa9

fs/file_table.c

+2 −1
Original line number Diff line number Diff line
@@ -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.