io-wq: provide IO_WQ_* constants for IORING_REGISTER_IOWQ_MAX_WORKERS arg items

The items passed in the array pointed by the arg parameter
of IORING_REGISTER_IOWQ_MAX_WORKERS io_uring_register operation
carry certain semantics: they refer to different io-wq worker categories;
provide IO_WQ_* constants in the UAPI, so these categories can be referenced
in the user space code.

Suggested-by: Jens Axboe <axboe@kernel.dk>
Complements: 2e480058ddc21ec5 ("io-wq: provide a way to limit max number of workers")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Link: https://lore.kernel.org/r/20210913154415.GA12890@asgard.redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 3d4460d..c2e0e8e 100644 (file)
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -14,6 +14,7 @@
 #include <linux/rculist_nulls.h>
 #include <linux/cpu.h>
 #include <linux/tracehook.h>
+#include <uapi/linux/io_uring.h>
 
 #include "io-wq.h"
 
@@ -1281,6 +1282,10 @@ int io_wq_max_workers(struct io_wq *wq, int *new_count)
 {
        int i, node, prev = 0;
 
+       BUILD_BUG_ON((int) IO_WQ_ACCT_BOUND   != (int) IO_WQ_BOUND);
+       BUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND);
+       BUILD_BUG_ON((int) IO_WQ_ACCT_NR      != 2);
+
        for (i = 0; i < 2; i++) {
                if (new_count[i] > task_rlimit(current, RLIMIT_NPROC))
                        new_count[i] = task_rlimit(current, RLIMIT_NPROC);

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 59ef351..b270a07 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -317,13 +317,19 @@ enum {
        IORING_REGISTER_IOWQ_AFF                = 17,
        IORING_UNREGISTER_IOWQ_AFF              = 18,
 
-       /* set/get max number of workers */
+       /* set/get max number of io-wq workers */
        IORING_REGISTER_IOWQ_MAX_WORKERS        = 19,
 
        /* this goes last */
        IORING_REGISTER_LAST
 };
 
+/* io-wq worker categories */
+enum {
+       IO_WQ_BOUND,
+       IO_WQ_UNBOUND,
+};
+
 /* deprecated, see struct io_uring_rsrc_update */
 struct io_uring_files_update {
        __u32 offset;