From 6e73dffbb93cb8797cd4e42e98d837edf0f1a967 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Sat, 25 Jun 2022 11:55:38 +0100 Subject: [PATCH] io_uring: let to set a range for file slot allocation From recently io_uring provides an option to allocate a file index for operation registering fixed files. However, it's utterly unusable with mixed approaches when for a part of files the userspace knows better where to place it, as it may race and users don't have any sane way to pick a slot and hoping it will not be taken. Let the userspace to register a range of fixed file slots in which the auto-allocation happens. The use case is splittting the fixed table in two parts, where on of them is used for auto-allocation and another for slot-specified operations. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/66ab0394e436f38437cf7c44676e1920d09687ad.1656154403.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- include/linux/io_uring_types.h | 3 +++ include/uapi/linux/io_uring.h | 13 +++++++++++++ io_uring/filetable.c | 24 ++++++++++++++++++++---- io_uring/filetable.h | 20 +++++++++++++++++--- io_uring/io_uring.c | 6 ++++++ io_uring/rsrc.c | 2 ++ 6 files changed, 61 insertions(+), 7 deletions(-) diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index 3ca8f363f504..26ef11e978d4 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -233,6 +233,9 @@ struct io_ring_ctx { unsigned long check_cq; + unsigned int file_alloc_start; + unsigned int file_alloc_end; + struct { /* * We cache a range of free CQEs we can use, once exhausted it diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h index f378eabbff21..cf95354198a3 100644 --- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -449,6 +449,9 @@ enum { /* sync cancelation API */ IORING_REGISTER_SYNC_CANCEL = 24, + /* register a range of fixed file slots for automatic slot allocation */ + IORING_REGISTER_FILE_ALLOC_RANGE = 25, + /* this goes last */ IORING_REGISTER_LAST }; @@ -595,4 +598,14 @@ struct io_uring_sync_cancel_reg { __u64 pad[4]; }; +/* + * Argument for IORING_REGISTER_FILE_ALLOC_RANGE + * The range is specified as [off, off + len) + */ +struct io_uring_file_index_range { + __u32 off; + __u32 len; + __u64 resv; +}; + #endif diff --git a/io_uring/filetable.c b/io_uring/filetable.c index abaa5ba7f655..7b473259f3f4 100644 --- a/io_uring/filetable.c +++ b/io_uring/filetable.c @@ -16,7 +16,7 @@ static int io_file_bitmap_get(struct io_ring_ctx *ctx) { struct io_file_table *table = &ctx->file_table; - unsigned long nr = ctx->nr_user_files; + unsigned long nr = ctx->file_alloc_end; int ret; do { @@ -24,11 +24,10 @@ static int io_file_bitmap_get(struct io_ring_ctx *ctx) if (ret != nr) return ret; - if (!table->alloc_hint) + if (table->alloc_hint == ctx->file_alloc_start) break; - nr = table->alloc_hint; - table->alloc_hint = 0; + table->alloc_hint = ctx->file_alloc_start; } while (1); return -ENFILE; @@ -175,3 +174,20 @@ int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset) io_rsrc_node_switch(ctx, ctx->file_data); return 0; } + +int io_register_file_alloc_range(struct io_ring_ctx *ctx, + struct io_uring_file_index_range __user *arg) +{ + struct io_uring_file_index_range range; + u32 end; + + if (copy_from_user(&range, arg, sizeof(range))) + return -EFAULT; + if (check_add_overflow(range.off, range.len, &end)) + return -EOVERFLOW; + if (range.resv || end > ctx->nr_user_files) + return -EINVAL; + + io_file_table_set_alloc_range(ctx, range.off, range.len); + return 0; +} diff --git a/io_uring/filetable.h b/io_uring/filetable.h index 79eb50c1980e..ff3a712e11bf 100644 --- a/io_uring/filetable.h +++ b/io_uring/filetable.h @@ -3,9 +3,7 @@ #define IOU_FILE_TABLE_H #include - -struct io_ring_ctx; -struct io_kiocb; +#include /* * FFS_SCM is only available on 64-bit archs, for 32-bit we just define it as 0 @@ -33,6 +31,9 @@ int __io_fixed_fd_install(struct io_ring_ctx *ctx, struct file *file, unsigned int file_slot); int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset); +int io_register_file_alloc_range(struct io_ring_ctx *ctx, + struct io_uring_file_index_range __user *arg); + unsigned int io_file_get_flags(struct file *file); static inline void io_file_bitmap_clear(struct io_file_table *table, int bit) @@ -71,4 +72,17 @@ static inline void io_fixed_file_set(struct io_fixed_file *file_slot, file_slot->file_ptr = file_ptr; } +static inline void io_reset_alloc_hint(struct io_ring_ctx *ctx) +{ + ctx->file_table.alloc_hint = ctx->file_alloc_start; +} + +static inline void io_file_table_set_alloc_range(struct io_ring_ctx *ctx, + unsigned off, unsigned len) +{ + ctx->file_alloc_start = off; + ctx->file_alloc_end = off + len; + io_reset_alloc_hint(ctx); +} + #endif diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 070ee9ec9ee7..745264938a48 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3866,6 +3866,12 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, break; ret = io_sync_cancel(ctx, arg); break; + case IORING_REGISTER_FILE_ALLOC_RANGE: + ret = -EINVAL; + if (!arg || nr_args) + break; + ret = io_register_file_alloc_range(ctx, arg); + break; default: ret = -EINVAL; break; diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index 706fa020505b..d2e589c703d0 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -1012,6 +1012,8 @@ int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg, io_file_bitmap_set(&ctx->file_table, i); } + /* default it to the whole table */ + io_file_table_set_alloc_range(ctx, 0, ctx->nr_user_files); io_rsrc_node_switch(ctx, NULL); return 0; fail: