在 2022/5/9 下午11:50, Jens Axboe 写道:
If the application passes in IORING_FILE_INDEX_ALLOC as the file_slot,
then that's a hint to allocate a fixed file descriptor rather than have
one be passed in directly.
This can be useful for having io_uring manage the direct descriptor space.
Normal open direct requests will complete with 0 for success, and < 0
in case of error. If io_uring is asked to allocated the direct descriptor,
then the direct descriptor is returned in case of success.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
fs/io_uring.c | 32 +++++++++++++++++++++++++++++---
include/uapi/linux/io_uring.h | 9 +++++++++
2 files changed, 38 insertions(+), 3 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 8c40411a7e78..ef999d0e09de 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4697,7 +4697,7 @@ 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)
+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;
@@ -4722,6 +4722,32 @@ static int __maybe_unused io_file_bitmap_get(struct io_ring_ctx *ctx)
return -ENFILE;
}
+static int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags,
+ struct file *file, unsigned int file_slot)
+{
+ int alloc_slot = file_slot == IORING_FILE_INDEX_ALLOC;
+ struct io_ring_ctx *ctx = req->ctx;
+ int ret;
+
+ if (alloc_slot) {
+ io_ring_submit_lock(ctx, issue_flags);
+ file_slot = io_file_bitmap_get(ctx);
+ if (unlikely(file_slot < 0)) {
+ io_ring_submit_unlock(ctx, issue_flags);
+ return file_slot;
+ }
+ }
if (alloc_slot) {
...
} else {
file_slot -= 1;
}
Otherwise there is off-by-one error.
Others looks good,
Reviewed-by: Hao Xu <howeyxu@xxxxxxxxxxx>
