io_uring: remove any grabbing of context

The async workers are siblings of the task itself, so by definition we
have all the state that we need. Remove any of the state grabbing that
we have, and requests flagging what they need.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io-wq.h b/fs/io-wq.h
index 83d56ad..bbe05dd 100644 (file)
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -11,13 +11,6 @@ enum {
        IO_WQ_WORK_UNBOUND      = 4,
        IO_WQ_WORK_CONCURRENT   = 16,
 
-       IO_WQ_WORK_FILES        = 32,
-       IO_WQ_WORK_FS           = 64,
-       IO_WQ_WORK_MM           = 128,
-       IO_WQ_WORK_CREDS        = 256,
-       IO_WQ_WORK_BLKCG        = 512,
-       IO_WQ_WORK_FSIZE        = 1024,
-
        IO_WQ_HASH_SHIFT        = 24,   /* upper 8 bits are used for hash key */
 };
 

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 9d22ec9..6e88295 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -838,7 +838,6 @@ struct io_op_def {
        unsigned                plug : 1;
        /* size of async data needed, if any */
        unsigned short          async_size;
-       unsigned                work_flags;
 };
 
 static const struct io_op_def io_op_defs[] = {
@@ -851,7 +850,6 @@ static const struct io_op_def io_op_defs[] = {
                .needs_async_data       = 1,
                .plug                   = 1,
                .async_size             = sizeof(struct io_async_rw),
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
        },
        [IORING_OP_WRITEV] = {
                .needs_file             = 1,
@@ -861,12 +859,9 @@ static const struct io_op_def io_op_defs[] = {
                .needs_async_data       = 1,
                .plug                   = 1,
                .async_size             = sizeof(struct io_async_rw),
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG |
-                                               IO_WQ_WORK_FSIZE,
        },
        [IORING_OP_FSYNC] = {
                .needs_file             = 1,
-               .work_flags             = IO_WQ_WORK_BLKCG,
        },
        [IORING_OP_READ_FIXED] = {
                .needs_file             = 1,
@@ -874,7 +869,6 @@ static const struct io_op_def io_op_defs[] = {
                .pollin                 = 1,
                .plug                   = 1,
                .async_size             = sizeof(struct io_async_rw),
-               .work_flags             = IO_WQ_WORK_BLKCG | IO_WQ_WORK_MM,
        },
        [IORING_OP_WRITE_FIXED] = {
                .needs_file             = 1,
@@ -883,8 +877,6 @@ static const struct io_op_def io_op_defs[] = {
                .pollout                = 1,
                .plug                   = 1,
                .async_size             = sizeof(struct io_async_rw),
-               .work_flags             = IO_WQ_WORK_BLKCG | IO_WQ_WORK_FSIZE |
-                                               IO_WQ_WORK_MM,
        },
        [IORING_OP_POLL_ADD] = {
                .needs_file             = 1,
@@ -893,7 +885,6 @@ static const struct io_op_def io_op_defs[] = {
        [IORING_OP_POLL_REMOVE] = {},
        [IORING_OP_SYNC_FILE_RANGE] = {
                .needs_file             = 1,
-               .work_flags             = IO_WQ_WORK_BLKCG,
        },
        [IORING_OP_SENDMSG] = {
                .needs_file             = 1,
@@ -901,8 +892,6 @@ static const struct io_op_def io_op_defs[] = {
                .pollout                = 1,
                .needs_async_data       = 1,
                .async_size             = sizeof(struct io_async_msghdr),
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG |
-                                               IO_WQ_WORK_FS,
        },
        [IORING_OP_RECVMSG] = {
                .needs_file             = 1,
@@ -911,29 +900,23 @@ static const struct io_op_def io_op_defs[] = {
                .buffer_select          = 1,
                .needs_async_data       = 1,
                .async_size             = sizeof(struct io_async_msghdr),
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG |
-                                               IO_WQ_WORK_FS,
        },
        [IORING_OP_TIMEOUT] = {
                .needs_async_data       = 1,
                .async_size             = sizeof(struct io_timeout_data),
-               .work_flags             = IO_WQ_WORK_MM,
        },
        [IORING_OP_TIMEOUT_REMOVE] = {
                /* used by timeout updates' prep() */
-               .work_flags             = IO_WQ_WORK_MM,
        },
        [IORING_OP_ACCEPT] = {
                .needs_file             = 1,
                .unbound_nonreg_file    = 1,
                .pollin                 = 1,
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_FILES,
        },
        [IORING_OP_ASYNC_CANCEL] = {},
        [IORING_OP_LINK_TIMEOUT] = {
                .needs_async_data       = 1,
                .async_size             = sizeof(struct io_timeout_data),
-               .work_flags             = IO_WQ_WORK_MM,
        },
        [IORING_OP_CONNECT] = {
                .needs_file             = 1,
@@ -941,26 +924,14 @@ static const struct io_op_def io_op_defs[] = {
                .pollout                = 1,
                .needs_async_data       = 1,
                .async_size             = sizeof(struct io_async_connect),
-               .work_flags             = IO_WQ_WORK_MM,
        },
        [IORING_OP_FALLOCATE] = {
                .needs_file             = 1,
-               .work_flags             = IO_WQ_WORK_BLKCG | IO_WQ_WORK_FSIZE,
-       },
-       [IORING_OP_OPENAT] = {
-               .work_flags             = IO_WQ_WORK_FILES | IO_WQ_WORK_BLKCG |
-                                               IO_WQ_WORK_FS | IO_WQ_WORK_MM,
-       },
-       [IORING_OP_CLOSE] = {
-               .work_flags             = IO_WQ_WORK_FILES | IO_WQ_WORK_BLKCG,
-       },
-       [IORING_OP_FILES_UPDATE] = {
-               .work_flags             = IO_WQ_WORK_FILES | IO_WQ_WORK_MM,
-       },
-       [IORING_OP_STATX] = {
-               .work_flags             = IO_WQ_WORK_FILES | IO_WQ_WORK_MM |
-                                               IO_WQ_WORK_FS | IO_WQ_WORK_BLKCG,
        },
+       [IORING_OP_OPENAT] = {},
+       [IORING_OP_CLOSE] = {},
+       [IORING_OP_FILES_UPDATE] = {},
+       [IORING_OP_STATX] = {},
        [IORING_OP_READ] = {
                .needs_file             = 1,
                .unbound_nonreg_file    = 1,
@@ -968,7 +939,6 @@ static const struct io_op_def io_op_defs[] = {
                .buffer_select          = 1,
                .plug                   = 1,
                .async_size             = sizeof(struct io_async_rw),
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
        },
        [IORING_OP_WRITE] = {
                .needs_file             = 1,
@@ -976,42 +946,31 @@ static const struct io_op_def io_op_defs[] = {
                .pollout                = 1,
                .plug                   = 1,
                .async_size             = sizeof(struct io_async_rw),
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG |
-                                               IO_WQ_WORK_FSIZE,
        },
        [IORING_OP_FADVISE] = {
                .needs_file             = 1,
-               .work_flags             = IO_WQ_WORK_BLKCG,
-       },
-       [IORING_OP_MADVISE] = {
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
        },
+       [IORING_OP_MADVISE] = {},
        [IORING_OP_SEND] = {
                .needs_file             = 1,
                .unbound_nonreg_file    = 1,
                .pollout                = 1,
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
        },
        [IORING_OP_RECV] = {
                .needs_file             = 1,
                .unbound_nonreg_file    = 1,
                .pollin                 = 1,
                .buffer_select          = 1,
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
        },
        [IORING_OP_OPENAT2] = {
-               .work_flags             = IO_WQ_WORK_FILES | IO_WQ_WORK_FS |
-                                               IO_WQ_WORK_BLKCG | IO_WQ_WORK_MM,
        },
        [IORING_OP_EPOLL_CTL] = {
                .unbound_nonreg_file    = 1,
-               .work_flags             = IO_WQ_WORK_FILES,
        },
        [IORING_OP_SPLICE] = {
                .needs_file             = 1,
                .hash_reg_file          = 1,
                .unbound_nonreg_file    = 1,
-               .work_flags             = IO_WQ_WORK_BLKCG,
        },
        [IORING_OP_PROVIDE_BUFFERS] = {},
        [IORING_OP_REMOVE_BUFFERS] = {},
@@ -1023,14 +982,8 @@ static const struct io_op_def io_op_defs[] = {
        [IORING_OP_SHUTDOWN] = {
                .needs_file             = 1,
        },
-       [IORING_OP_RENAMEAT] = {
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_FILES |
-                                               IO_WQ_WORK_FS | IO_WQ_WORK_BLKCG,
-       },
-       [IORING_OP_UNLINKAT] = {
-               .work_flags             = IO_WQ_WORK_MM | IO_WQ_WORK_FILES |
-                                               IO_WQ_WORK_FS | IO_WQ_WORK_BLKCG,
-       },
+       [IORING_OP_RENAMEAT] = {},
+       [IORING_OP_UNLINKAT] = {},
 };
 
 static void io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
@@ -1141,8 +1094,7 @@ static bool io_match_task(struct io_kiocb *head,
                        continue;
                if (req->file && req->file->f_op == &io_uring_fops)
                        return true;
-               if ((req->work.flags & IO_WQ_WORK_FILES) &&
-                   req->work.identity->files == files)
+               if (req->work.identity->files == files)
                        return true;
        }
        return false;
@@ -1219,20 +1171,15 @@ static int __io_sq_thread_acquire_mm(struct io_ring_ctx *ctx)
 static int __io_sq_thread_acquire_mm_files(struct io_ring_ctx *ctx,
                                           struct io_kiocb *req)
 {
-       const struct io_op_def *def = &io_op_defs[req->opcode];
        int ret;
 
-       if (def->work_flags & IO_WQ_WORK_MM) {
-               ret = __io_sq_thread_acquire_mm(ctx);
-               if (unlikely(ret))
-                       return ret;
-       }
+       ret = __io_sq_thread_acquire_mm(ctx);
+       if (unlikely(ret))
+               return ret;
 
-       if (def->needs_file || (def->work_flags & IO_WQ_WORK_FILES)) {
-               ret = __io_sq_thread_acquire_files(ctx);
-               if (unlikely(ret))
-                       return ret;
-       }
+       ret = __io_sq_thread_acquire_files(ctx);
+       if (unlikely(ret))
+               return ret;
 
        return 0;
 }
@@ -1416,28 +1363,6 @@ static void io_req_clean_work(struct io_kiocb *req)
        if (!(req->flags & REQ_F_WORK_INITIALIZED))
                return;
 
-       if (req->work.flags & IO_WQ_WORK_MM)
-               mmdrop(req->work.identity->mm);
-#ifdef CONFIG_BLK_CGROUP
-       if (req->work.flags & IO_WQ_WORK_BLKCG)
-               css_put(req->work.identity->blkcg_css);
-#endif
-       if (req->work.flags & IO_WQ_WORK_CREDS)
-               put_cred(req->work.identity->creds);
-       if (req->work.flags & IO_WQ_WORK_FS) {
-               struct fs_struct *fs = req->work.identity->fs;
-
-               spin_lock(&req->work.identity->fs->lock);
-               if (--fs->users)
-                       fs = NULL;
-               spin_unlock(&req->work.identity->fs->lock);
-               if (fs)
-                       free_fs_struct(fs);
-       }
-       if (req->work.flags & IO_WQ_WORK_FILES) {
-               put_files_struct(req->work.identity->files);
-               put_nsproxy(req->work.identity->nsproxy);
-       }
        if (req->flags & REQ_F_INFLIGHT) {
                struct io_ring_ctx *ctx = req->ctx;
                struct io_uring_task *tctx = req->task->io_uring;
@@ -1452,56 +1377,9 @@ static void io_req_clean_work(struct io_kiocb *req)
        }
 
        req->flags &= ~REQ_F_WORK_INITIALIZED;
-       req->work.flags &= ~(IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG | IO_WQ_WORK_FS |
-                            IO_WQ_WORK_CREDS | IO_WQ_WORK_FILES);
        io_put_identity(req->task->io_uring, req);
 }
 
-/*
- * Create a private copy of io_identity, since some fields don't match
- * the current context.
- */
-static bool io_identity_cow(struct io_kiocb *req)
-{
-       struct io_uring_task *tctx = current->io_uring;
-       const struct cred *creds = NULL;
-       struct io_identity *id;
-
-       if (req->work.flags & IO_WQ_WORK_CREDS)
-               creds = req->work.identity->creds;
-
-       id = kmemdup(req->work.identity, sizeof(*id), GFP_KERNEL);
-       if (unlikely(!id)) {
-               req->work.flags |= IO_WQ_WORK_CANCEL;
-               return false;
-       }
-
-       /*
-        * We can safely just re-init the creds we copied  Either the field
-        * matches the current one, or we haven't grabbed it yet. The only
-        * exception is ->creds, through registered personalities, so handle
-        * that one separately.
-        */
-       io_init_identity(id);
-       if (creds)
-               id->creds = creds;
-
-       /* add one for this request */
-       refcount_inc(&id->count);
-
-       /* drop tctx and req identity references, if needed */
-       if (tctx->identity != &tctx->__identity &&
-           refcount_dec_and_test(&tctx->identity->count))
-               kfree(tctx->identity);
-       if (req->work.identity != &tctx->__identity &&
-           refcount_dec_and_test(&req->work.identity->count))
-               kfree(req->work.identity);
-
-       req->work.identity = id;
-       tctx->identity = id;
-       return true;
-}
-
 static void io_req_track_inflight(struct io_kiocb *req)
 {
        struct io_ring_ctx *ctx = req->ctx;
@@ -1516,79 +1394,6 @@ static void io_req_track_inflight(struct io_kiocb *req)
        }
 }
 
-static bool io_grab_identity(struct io_kiocb *req)
-{
-       const struct io_op_def *def = &io_op_defs[req->opcode];
-       struct io_identity *id = req->work.identity;
-
-       if (def->work_flags & IO_WQ_WORK_FSIZE) {
-               if (id->fsize != rlimit(RLIMIT_FSIZE))
-                       return false;
-               req->work.flags |= IO_WQ_WORK_FSIZE;
-       }
-#ifdef CONFIG_BLK_CGROUP
-       if (!(req->work.flags & IO_WQ_WORK_BLKCG) &&
-           (def->work_flags & IO_WQ_WORK_BLKCG)) {
-               rcu_read_lock();
-               if (id->blkcg_css != blkcg_css()) {
-                       rcu_read_unlock();
-                       return false;
-               }
-               /*
-                * This should be rare, either the cgroup is dying or the task
-                * is moving cgroups. Just punt to root for the handful of ios.
-                */
-               if (css_tryget_online(id->blkcg_css))
-                       req->work.flags |= IO_WQ_WORK_BLKCG;
-               rcu_read_unlock();
-       }
-#endif
-       if (!(req->work.flags & IO_WQ_WORK_CREDS)) {
-               if (id->creds != current_cred())
-                       return false;
-               get_cred(id->creds);
-               req->work.flags |= IO_WQ_WORK_CREDS;
-       }
-#ifdef CONFIG_AUDIT
-       if (!uid_eq(current->loginuid, id->loginuid) ||
-           current->sessionid != id->sessionid)
-               return false;
-#endif
-       if (!(req->work.flags & IO_WQ_WORK_FS) &&
-           (def->work_flags & IO_WQ_WORK_FS)) {
-               if (current->fs != id->fs)
-                       return false;
-               spin_lock(&id->fs->lock);
-               if (!id->fs->in_exec) {
-                       id->fs->users++;
-                       req->work.flags |= IO_WQ_WORK_FS;
-               } else {
-                       req->work.flags |= IO_WQ_WORK_CANCEL;
-               }
-               spin_unlock(&current->fs->lock);
-       }
-       if (!(req->work.flags & IO_WQ_WORK_FILES) &&
-           (def->work_flags & IO_WQ_WORK_FILES) &&
-           !(req->flags & REQ_F_NO_FILE_TABLE)) {
-               if (id->files != current->files ||
-                   id->nsproxy != current->nsproxy)
-                       return false;
-               atomic_inc(&id->files->count);
-               get_nsproxy(id->nsproxy);
-               req->work.flags |= IO_WQ_WORK_FILES;
-               io_req_track_inflight(req);
-       }
-       if (!(req->work.flags & IO_WQ_WORK_MM) &&
-           (def->work_flags & IO_WQ_WORK_MM)) {
-               if (id->mm != current->mm)
-                       return false;
-               mmgrab(id->mm);
-               req->work.flags |= IO_WQ_WORK_MM;
-       }
-
-       return true;
-}
-
 static void io_prep_async_work(struct io_kiocb *req)
 {
        const struct io_op_def *def = &io_op_defs[req->opcode];
@@ -1606,17 +1411,6 @@ static void io_prep_async_work(struct io_kiocb *req)
                if (def->unbound_nonreg_file)
                        req->work.flags |= IO_WQ_WORK_UNBOUND;
        }
-
-       /* if we fail grabbing identity, we must COW, regrab, and retry */
-       if (io_grab_identity(req))
-               return;
-
-       if (!io_identity_cow(req))
-               return;
-
-       /* can't fail at this point */
-       if (!io_grab_identity(req))
-               WARN_ON(1);
 }
 
 static void io_prep_async_link(struct io_kiocb *req)
@@ -6583,7 +6377,6 @@ static void __io_queue_sqe(struct io_kiocb *req)
        int ret;
 
        if ((req->flags & REQ_F_WORK_INITIALIZED) &&
-           (req->work.flags & IO_WQ_WORK_CREDS) &&
            req->work.identity->creds != current_cred())
                old_creds = override_creds(req->work.identity->creds);
 
@@ -6725,7 +6518,6 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
                __io_req_init_async(req);
                get_cred(iod->creds);
                req->work.identity = iod;
-               req->work.flags |= IO_WQ_WORK_CREDS;
        }
 
        state = &ctx->submit_state;