io_uring: change registration/upd/rsrc tagging ABI

There are ABI moments about recently added rsrc registration/update and
tagging that might become a nuisance in the future. First,
IORING_REGISTER_RSRC[_UPD] hide different types of resources under it,
so breaks fine control over them by restrictions. It works for now, but
once those are wanted under restrictions it would require a rework.

It was also inconvenient trying to fit a new resource not supporting
all the features (e.g. dynamic update) into the interface, so better
to return to IORING_REGISTER_* top level dispatching.

Second, register/update were considered to accept a type of resource,
however that's not a good idea because there might be several ways of
registration of a single resource type, e.g. we may want to add
non-contig buffers or anything more exquisite as dma mapped memory.
So, remove IORING_RSRC_[FILE,BUFFER] out of the ABI, and place them
internally for now to limit changes.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9b554897a7c17ad6e3becc48dfed2f7af9f423d5.1623339162.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 42380ed..663fef3 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -783,6 +783,11 @@ struct io_task_work {
        task_work_func_t        func;
 };
 
+enum {
+       IORING_RSRC_FILE                = 0,
+       IORING_RSRC_BUFFER              = 1,
+};
+
 /*
  * NOTE! Each of the iocb union members has the file pointer
  * as the first entry in their struct definition. So you can
@@ -9911,7 +9916,7 @@ static int io_register_files_update(struct io_ring_ctx *ctx, void __user *arg,
 }
 
 static int io_register_rsrc_update(struct io_ring_ctx *ctx, void __user *arg,
-                                  unsigned size)
+                                  unsigned size, unsigned type)
 {
        struct io_uring_rsrc_update2 up;
 
@@ -9919,13 +9924,13 @@ static int io_register_rsrc_update(struct io_ring_ctx *ctx, void __user *arg,
                return -EINVAL;
        if (copy_from_user(&up, arg, sizeof(up)))
                return -EFAULT;
-       if (!up.nr)
+       if (!up.nr || up.resv)
                return -EINVAL;
-       return __io_register_rsrc_update(ctx, up.type, &up, up.nr);
+       return __io_register_rsrc_update(ctx, type, &up, up.nr);
 }
 
 static int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg,
-                           unsigned int size)
+                           unsigned int size, unsigned int type)
 {
        struct io_uring_rsrc_register rr;
 
@@ -9936,10 +9941,10 @@ static int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg,
        memset(&rr, 0, sizeof(rr));
        if (copy_from_user(&rr, arg, size))
                return -EFAULT;
-       if (!rr.nr)
+       if (!rr.nr || rr.resv || rr.resv2)
                return -EINVAL;
 
-       switch (rr.type) {
+       switch (type) {
        case IORING_RSRC_FILE:
                return io_sqe_files_register(ctx, u64_to_user_ptr(rr.data),
                                             rr.nr, u64_to_user_ptr(rr.tags));
@@ -9961,8 +9966,10 @@ static bool io_register_op_must_quiesce(int op)
        case IORING_REGISTER_PROBE:
        case IORING_REGISTER_PERSONALITY:
        case IORING_UNREGISTER_PERSONALITY:
-       case IORING_REGISTER_RSRC:
-       case IORING_REGISTER_RSRC_UPDATE:
+       case IORING_REGISTER_FILES2:
+       case IORING_REGISTER_FILES_UPDATE2:
+       case IORING_REGISTER_BUFFERS2:
+       case IORING_REGISTER_BUFFERS_UPDATE:
                return false;
        default:
                return true;
@@ -10088,11 +10095,19 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
        case IORING_REGISTER_RESTRICTIONS:
                ret = io_register_restrictions(ctx, arg, nr_args);
                break;
-       case IORING_REGISTER_RSRC:
-               ret = io_register_rsrc(ctx, arg, nr_args);
+       case IORING_REGISTER_FILES2:
+               ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_FILE);
+               break;
+       case IORING_REGISTER_FILES_UPDATE2:
+               ret = io_register_rsrc_update(ctx, arg, nr_args,
+                                             IORING_RSRC_FILE);
+               break;
+       case IORING_REGISTER_BUFFERS2:
+               ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_BUFFER);
                break;
-       case IORING_REGISTER_RSRC_UPDATE:
-               ret = io_register_rsrc_update(ctx, arg, nr_args);
+       case IORING_REGISTER_BUFFERS_UPDATE:
+               ret = io_register_rsrc_update(ctx, arg, nr_args,
+                                             IORING_RSRC_BUFFER);
                break;
        default:
                ret = -EINVAL;

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index e1ae466..48b4ddc 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -298,8 +298,12 @@ enum {
        IORING_UNREGISTER_PERSONALITY           = 10,
        IORING_REGISTER_RESTRICTIONS            = 11,
        IORING_REGISTER_ENABLE_RINGS            = 12,
-       IORING_REGISTER_RSRC                    = 13,
-       IORING_REGISTER_RSRC_UPDATE             = 14,
+
+       /* extended with tagging */
+       IORING_REGISTER_FILES2                  = 13,
+       IORING_REGISTER_FILES_UPDATE2           = 14,
+       IORING_REGISTER_BUFFERS2                = 15,
+       IORING_REGISTER_BUFFERS_UPDATE          = 16,
 
        /* this goes last */
        IORING_REGISTER_LAST
@@ -312,14 +316,10 @@ struct io_uring_files_update {
        __aligned_u64 /* __s32 * */ fds;
 };
 
-enum {
-       IORING_RSRC_FILE                = 0,
-       IORING_RSRC_BUFFER              = 1,
-};
-
 struct io_uring_rsrc_register {
-       __u32 type;
        __u32 nr;
+       __u32 resv;
+       __u64 resv2;
        __aligned_u64 data;
        __aligned_u64 tags;
 };
@@ -335,8 +335,8 @@ struct io_uring_rsrc_update2 {
        __u32 resv;
        __aligned_u64 data;
        __aligned_u64 tags;
-       __u32 type;
        __u32 nr;
+       __u32 resv2;
 };
 
 /* Skip updating fd indexes set to this value in the fd table */