From bfc0aa7a512f9a4462a88ca7352b00b83f8d68fd Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Wed, 11 Sep 2024 13:54:32 -0600
Subject: [PATCH] io_uring/rsrc: add reference count to struct io_mapped_ubuf
Currently there's a single ring owner of a mapped buffer, and hence the
reference count will always be 1 when it's torn down and freed. However,
in preparation for being able to link io_mapped_ubuf to different spots,
add a reference count to manage the lifetime of it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
io_uring/rsrc.c | 3 +++
io_uring/rsrc.h | 1 +
2 files changed, 4 insertions(+)
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index d42114845fac6..28f98de3c3042 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -116,6 +116,8 @@ static void io_buffer_unmap(struct io_ring_ctx *ctx, struct io_mapped_ubuf **slo
*slot = NULL;
if (imu != &dummy_ubuf) {
+ if (!refcount_dec_and_test(&imu->refs))
+ return;
for (i = 0; i < imu->nr_bvecs; i++)
unpin_user_page(imu->bvec[i].bv_page);
if (imu->acct_pages)
@@ -990,6 +992,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
imu->folio_shift = data.folio_shift;
imu->folio_mask = ~((1UL << data.folio_shift) - 1);
}
+ refcount_set(&imu->refs, 1);
off = (unsigned long) iov->iov_base & ~imu->folio_mask;
*pimu = imu;
ret = 0;
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 3d0dda3556e6e..98a253172c273 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -47,6 +47,7 @@ struct io_mapped_ubuf {
unsigned int folio_shift;
unsigned long acct_pages;
unsigned long folio_mask;
+ refcount_t refs;
struct bio_vec bvec[] __counted_by(nr_bvecs);
};
--
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