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authorJens Axboe <axboe@kernel.dk>2022-05-07 14:18:44 -0600
committerJens Axboe <axboe@kernel.dk>2022-05-09 06:29:53 -0600
commit0db0570a9f51b75693b0e9c7553be004521abceb (patch)
tree7426b81dbacf9a1e69145cc8204f325d3554a0e5
parent26e6b1abf6c6c7e142f183940f754bab69b76a05 (diff)
io_uring: allow allocated fixed files for openat/openat2
If the applications passes in UINT_MAX 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@kernel.dk>
-rw-r--r--fs/io_uring.c32
1 files changed, 29 insertions, 3 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index c671e9e70e42..5faff07a109b 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4702,7 +4702,7 @@ 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;
@@ -4727,6 +4727,32 @@ static int __maybe_unused io_file_bitmap_get(struct io_ring_ctx *ctx)
return -ENFILE;
}
+static int io_fixed_file_install(struct io_kiocb *req, unsigned int issue_flags,
+ struct file *file, unsigned int file_slot)
+{
+ int alloc_slot = file_slot == UINT_MAX;
+ 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;
+ }
+ }
+
+ ret = io_install_fixed_file(req, file, issue_flags, file_slot);
+ if (alloc_slot) {
+ io_ring_submit_unlock(ctx, issue_flags);
+ if (!ret)
+ return file_slot;
+ }
+
+ return ret;
+}
+
static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
{
struct open_flags op;
@@ -4782,8 +4808,8 @@ static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
if (!fixed)
fd_install(ret, file);
else
- ret = io_install_fixed_file(req, file, issue_flags,
- req->open.file_slot - 1);
+ ret = io_fixed_file_install(req, issue_flags, file,
+ req->open.file_slot);
err:
putname(req->open.filename);
req->flags &= ~REQ_F_NEED_CLEANUP;