io_uring: don't vmalloc rsrc tags

We don't really need vmalloc for keeping tags, it's not a hot path and
is there out of convenience, so replace it with two level tables to not
litter kernel virtual memory mappings.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/241a3422747113a8909e7e1030eb585d4a349e0d.1623634181.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0fbf194..bc4d03b 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -100,6 +100,10 @@
 #define IORING_MAX_RESTRICTIONS        (IORING_RESTRICTION_LAST + \
                                 IORING_REGISTER_LAST + IORING_OP_LAST)
 
+#define IO_RSRC_TAG_TABLE_SHIFT        9
+#define IO_RSRC_TAG_TABLE_MAX  (1U << IO_RSRC_TAG_TABLE_SHIFT)
+#define IO_RSRC_TAG_TABLE_MASK (IO_RSRC_TAG_TABLE_MAX - 1)
+
 #define IORING_MAX_REG_BUFFERS (1U << 14)
 
 #define SQE_VALID_FLAGS        (IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK| \
@@ -243,7 +247,8 @@ typedef void (rsrc_put_fn)(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc);
 struct io_rsrc_data {
        struct io_ring_ctx              *ctx;
 
-       u64                             *tags;
+       u64                             **tags;
+       unsigned int                    nr;
        rsrc_put_fn                     *do_put;
        atomic_t                        refs;
        struct completion               done;
@@ -7177,9 +7182,20 @@ static int io_rsrc_ref_quiesce(struct io_rsrc_data *data, struct io_ring_ctx *ct
        return ret;
 }
 
+static u64 *io_get_tag_slot(struct io_rsrc_data *data, unsigned int idx)
+{
+       unsigned int off = idx & IO_RSRC_TAG_TABLE_MASK;
+       unsigned int table_idx = idx >> IO_RSRC_TAG_TABLE_SHIFT;
+
+       return &data->tags[table_idx][off];
+}
+
 static void io_rsrc_data_free(struct io_rsrc_data *data)
 {
-       kvfree(data->tags);
+       size_t size = data->nr * sizeof(data->tags[0][0]);
+
+       if (data->tags)
+               io_free_page_table((void **)data->tags, size);
        kfree(data);
 }
 
@@ -7188,33 +7204,37 @@ static int io_rsrc_data_alloc(struct io_ring_ctx *ctx, rsrc_put_fn *do_put,
                              struct io_rsrc_data **pdata)
 {
        struct io_rsrc_data *data;
+       int ret = -ENOMEM;
        unsigned i;
 
        data = kzalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;
-
-       data->tags = kvcalloc(nr, sizeof(*data->tags), GFP_KERNEL);
+       data->tags = (u64 **)io_alloc_page_table(nr * sizeof(data->tags[0][0]));
        if (!data->tags) {
                kfree(data);
                return -ENOMEM;
        }
+
+       data->nr = nr;
+       data->ctx = ctx;
+       data->do_put = do_put;
        if (utags) {
+               ret = -EFAULT;
                for (i = 0; i < nr; i++) {
-                       if (copy_from_user(&data->tags[i], &utags[i],
-                                          sizeof(data->tags[i]))) {
-                               io_rsrc_data_free(data);
-                               return -EFAULT;
-                       }
+                       if (copy_from_user(io_get_tag_slot(data, i), &utags[i],
+                                          sizeof(data->tags[i])))
+                               goto fail;
                }
        }
 
        atomic_set(&data->refs, 1);
-       data->ctx = ctx;
-       data->do_put = do_put;
        init_completion(&data->done);
        *pdata = data;
        return 0;
+fail:
+       io_rsrc_data_free(data);
+       return ret;
 }
 
 static bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
@@ -7683,7 +7703,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
                /* allow sparse sets */
                if (fd == -1) {
                        ret = -EINVAL;
-                       if (unlikely(ctx->file_data->tags[i]))
+                       if (unlikely(*io_get_tag_slot(ctx->file_data, i)))
                                goto out_fput;
                        continue;
                }
@@ -7781,7 +7801,7 @@ static int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx,
        if (!prsrc)
                return -ENOMEM;
 
-       prsrc->tag = data->tags[idx];
+       prsrc->tag = *io_get_tag_slot(data, idx);
        prsrc->rsrc = rsrc;
        list_add(&prsrc->list, &node->rsrc_list);
        return 0;
@@ -7851,7 +7871,7 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
                                err = -EBADF;
                                break;
                        }
-                       data->tags[up->offset + done] = tag;
+                       *io_get_tag_slot(data, up->offset + done) = tag;
                        io_fixed_file_set(file_slot, file);
                        err = io_sqe_file_register(ctx, file, i);
                        if (err) {
@@ -8437,7 +8457,7 @@ static int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
                ret = io_buffer_validate(&iov);
                if (ret)
                        break;
-               if (!iov.iov_base && data->tags[i]) {
+               if (!iov.iov_base && *io_get_tag_slot(data, i)) {
                        ret = -EINVAL;
                        break;
                }
@@ -8510,7 +8530,7 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
                }
 
                ctx->user_bufs[i] = imu;
-               ctx->buf_data->tags[offset] = tag;
+               *io_get_tag_slot(ctx->buf_data, offset) = tag;
        }
 
        if (needs_switch)