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io_uring/rsrc: allow cloning at an offset

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Right now buffer cloning is an all-or-nothing kind of thing - either the
whole table is cloned from a source to a destination ring, or nothing at
all.

However, it's not always desired to clone the whole thing. Allow for
the application to specify a source and destination offset, and a
number of buffers to clone. If the destination offset is non-zero, then
allocate sparse nodes upfront.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2024-10-28 18:43:13 -06:00
parent d50f94d761
commit b16e920a19
2 changed files with 30 additions and 7 deletions
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5
include/uapi/linux/io_uring.h
View File

@ -719,7 +719,10 @@ enum {
struct io_uring_clone_buffers {
__u32 src_fd;
__u32 flags;
__u32 pad[6];
__u32 src_off;
__u32 dst_off;
__u32 nr;
__u32 pad[3];
};
struct io_uring_buf {

32
io_uring/rsrc.c
View File

@ -927,10 +927,11 @@ int io_import_fixed(int ddir, struct iov_iter *iter,
return 0;
}
static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx)
static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx,
struct io_uring_clone_buffers *arg)
{
int i, ret, nbufs, off, nr;
struct io_rsrc_data data;
int i, ret, nbufs;
/*
* Drop our own lock here. We'll setup the data we need and reference
@ -943,11 +944,29 @@ static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx
nbufs = src_ctx->buf_table.nr;
if (!nbufs)
goto out_unlock;
ret = io_rsrc_data_alloc(&data, nbufs);
ret = -EINVAL;
if (!arg->nr)
arg->nr = nbufs;
else if (arg->nr > nbufs)
goto out_unlock;
ret = -EOVERFLOW;
if (check_add_overflow(arg->nr, arg->src_off, &off))
goto out_unlock;
if (off > nbufs)
goto out_unlock;
if (check_add_overflow(arg->nr, arg->dst_off, &off))
goto out_unlock;
ret = -EINVAL;
if (off > IORING_MAX_REG_BUFFERS)
goto out_unlock;
ret = io_rsrc_data_alloc(&data, off);
if (ret)
goto out_unlock;
for (i = 0; i < nbufs; i++) {
off = arg->dst_off;
i = arg->src_off;
nr = arg->nr;
while (nr--) {
struct io_rsrc_node *dst_node, *src_node;
src_node = io_rsrc_node_lookup(&src_ctx->buf_table, i);
@ -963,7 +982,8 @@ static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx
refcount_inc(&src_node->buf->refs);
dst_node->buf = src_node->buf;
}
data.nodes[i] = dst_node;
data.nodes[off++] = dst_node;
i++;
}
/* Have a ref on the bufs now, drop src lock and re-grab our own lock */
@ -1018,7 +1038,7 @@ int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg)
file = io_uring_register_get_file(buf.src_fd, registered_src);
if (IS_ERR(file))
return PTR_ERR(file);
ret = io_clone_buffers(ctx, file->private_data);
ret = io_clone_buffers(ctx, file->private_data, &buf);
if (!registered_src)
fput(file);
return ret;