From b70b8e3331d8134ab993368a6e0eb18c1acb1b1d Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Sat, 7 May 2022 14:20:40 -0600
Subject: [PATCH] io_uring: add basic fixed file allocator
Git-commit: b70b8e3331d8134ab993368a6e0eb18c1acb1b1d
Patch-mainline: v5.19-rc1
References: bsc#1205205
Applications currently always pick where they want fixed files to go.
In preparation for allowing these types of commands with multishot
support, add a basic allocator in the fixed file table.
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
fs/io_uring.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index f8a685cc0363..8c40411a7e78 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -258,6 +258,7 @@ struct io_rsrc_put {
struct io_file_table {
struct io_fixed_file *files;
unsigned long *bitmap;
+ unsigned int alloc_hint;
};
struct io_rsrc_node {
@@ -4696,6 +4697,31 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
return __io_openat_prep(req, sqe);
}
+static int __maybe_unused io_file_bitmap_get(struct io_ring_ctx *ctx)
+{
+ struct io_file_table *table = &ctx->file_table;
+ unsigned long nr = ctx->nr_user_files;
+ int ret;
+
+ if (table->alloc_hint >= nr)
+ table->alloc_hint = 0;
+
+ do {
+ ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint);
+ if (ret != nr) {
+ table->alloc_hint = ret + 1;
+ return ret;
+ }
+ if (!table->alloc_hint)
+ break;
+
+ nr = table->alloc_hint;
+ table->alloc_hint = 0;
+ } while (1);
+
+ return -ENFILE;
+}
+
static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
{
struct open_flags op;
@@ -8664,11 +8690,14 @@ static inline void io_file_bitmap_set(struct io_file_table *table, int bit)
{
WARN_ON_ONCE(test_bit(bit, table->bitmap));
__set_bit(bit, table->bitmap);
+ if (bit == table->alloc_hint)
+ table->alloc_hint++;
}
static inline void io_file_bitmap_clear(struct io_file_table *table, int bit)
{
__clear_bit(bit, table->bitmap);
+ table->alloc_hint = bit;
}
static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
--
2.35.3