[PATCH 4/5] io_uring/dma-buf: switch to tag file filtering

[Pavel Begunkov]

Instead of enforcing that a dma-buf-io ctx is used only with the
registered file, allow sharing using tags.

Fixes: 62e4bf5b25d44 ("io_uring/rsrc: add dmabuf backed registered buffers")
Signed-off-by: Pavel Begunkov <asml.sile...@gmail.com>
---
 io_uring/dma-buf.c | 3 +--
 io_uring/dma-buf.h | 6 ++----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/io_uring/dma-buf.c b/io_uring/dma-buf.c
index 6f1d21c0f558..f25749f7da22 100644
--- a/io_uring/dma-buf.c
+++ b/io_uring/dma-buf.c
@@ -4,7 +4,6 @@ static inline void io_release_dmabuf(void *priv)
 {
        struct io_buf_dma *bd = io_priv_to_dmabuf(priv);
 
-       fput(bd->target_file);
        dma_buf_io_ctx_release(bd->ctx);
        kfree(bd);
 }
@@ -52,13 +51,13 @@ int __io_register_dmabuf(struct io_ring_ctx *ctx,
        if (ret)
                goto err;
 
-       bd->target_file = target_file;
        imu->len = dmabuf->size;
        imu->release = io_release_dmabuf;
        imu->priv = bd;
        imu->flags = IO_REGBUF_F_DMABUF;
        imu->dir = IO_BUF_DEST | IO_BUF_SOURCE;
        dma_buf_put(dmabuf);
+       fput(target_file);
        return 0;
 err:
        kfree(bd);
diff --git a/io_uring/dma-buf.h b/io_uring/dma-buf.h
index a97412ebbb3f..9bd7c8c64397 100644
--- a/io_uring/dma-buf.h
+++ b/io_uring/dma-buf.h
@@ -9,7 +9,6 @@
 
 struct io_buf_dma {
        struct dma_buf_io_ctx           *ctx;
-       struct file                     *target_file;
 };
 
 static inline struct io_buf_dma *io_priv_to_dmabuf(void *data)
@@ -63,11 +62,10 @@ static inline int io_import_dmabuf_map(struct io_kiocb *req,
                                struct io_mapped_ubuf *imu,
                                size_t len, size_t offset)
 {
-       struct io_buf_dma *bd = io_buf_to_dmabuf(imu);
-
        if (!IS_ENABLED(CONFIG_DMA_SHARED_BUFFER))
                return -EOPNOTSUPP;
-       if (req->file != bd->target_file)
+       if (unlikely(!dma_buf_io_file_compatible(io_buf_to_dmabuf(imu)->ctx,
+                                                req->file)))
                return -EBADF;
        req->flags |= REQ_F_DMABUF;
        iov_iter_dmabuf_map(iter, ddir, NULL, offset, len);
-- 
2.54.0