Merge tag 'io_uring-6.0-2022-09-02' of git://git.kernel.dk/linux-block

Pull io_uring fixes from Jens Axboe:

 - A single fix for over-eager retries for networking (Pavel)

 - Revert the notification slot support for zerocopy sends.

   It turns out that even after more than a year or development and
   testing, there's not full agreement on whether just using plain
   ordered notifications is Good Enough to avoid the complexity of using
   the notifications slots. Because of that, we decided that it's best
   left to a future final decision.

   We can always bring back this feature, but we can't really change it
   or remove it once we've released 6.0 with it enabled. The reverts
   leave the usual CQE notifications as the primary interface for
   knowing when data was sent, and when it was acked. (Pavel)

* tag 'io_uring-6.0-2022-09-02' of git://git.kernel.dk/linux-block:
  selftests/net: return back io_uring zc send tests
  io_uring/net: simplify zerocopy send user API
  io_uring/notif: remove notif registration
  Revert "io_uring: rename IORING_OP_FILES_UPDATE"
  Revert "io_uring: add zc notification flush requests"
  selftests/net: temporarily disable io_uring zc test
  io_uring/net: fix overexcessive retries

8 files changed, 52 insertions, 230 deletions

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 77616279000b..f9be9b7eb654 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2640,7 +2640,6 @@ static __cold void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 		io_unregister_personality(ctx, index);
 	if (ctx->rings)
 		io_poll_remove_all(ctx, NULL, true);
-	io_notif_unregister(ctx);
 	mutex_unlock(&ctx->uring_lock);
 
 	/* failed during ring init, it couldn't have issued any requests */
@@ -3839,15 +3838,6 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 			break;
 		ret = io_register_file_alloc_range(ctx, arg);
 		break;
-	case IORING_REGISTER_NOTIFIERS:
-		ret = io_notif_register(ctx, arg, nr_args);
-		break;
-	case IORING_UNREGISTER_NOTIFIERS:
-		ret = -EINVAL;
-		if (arg || nr_args)
-			break;
-		ret = io_notif_unregister(ctx);
-		break;
 	default:
 		ret = -EINVAL;
 		break;
@@ -3933,8 +3923,8 @@ static int __init io_uring_init(void)
 	BUILD_BUG_SQE_ELEM(42, __u16,  personality);
 	BUILD_BUG_SQE_ELEM(44, __s32,  splice_fd_in);
 	BUILD_BUG_SQE_ELEM(44, __u32,  file_index);
-	BUILD_BUG_SQE_ELEM(44, __u16,  notification_idx);
-	BUILD_BUG_SQE_ELEM(46, __u16,  addr_len);
+	BUILD_BUG_SQE_ELEM(44, __u16,  addr_len);
+	BUILD_BUG_SQE_ELEM(46, __u16,  __pad3[0]);
 	BUILD_BUG_SQE_ELEM(48, __u64,  addr3);
 	BUILD_BUG_SQE_ELEM_SIZE(48, 0, cmd);
 	BUILD_BUG_SQE_ELEM(56, __u64,  __pad2);
diff --git a/io_uring/net.c b/io_uring/net.c
index 0af8a02df580..7047c1342541 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -65,12 +65,12 @@ struct io_sendzc {
 	struct file			*file;
 	void __user			*buf;
 	size_t				len;
-	u16				slot_idx;
 	unsigned			msg_flags;
 	unsigned			flags;
 	unsigned			addr_len;
 	void __user			*addr;
 	size_t				done_io;
+	struct io_kiocb 		*notif;
 };
 
 #define IO_APOLL_MULTI_POLLED (REQ_F_APOLL_MULTISHOT | REQ_F_POLLED)
@@ -879,17 +879,31 @@ out_free:
 	return ret;
 }
 
+void io_sendzc_cleanup(struct io_kiocb *req)
+{
+	struct io_sendzc *zc = io_kiocb_to_cmd(req, struct io_sendzc);
+
+	zc->notif->flags |= REQ_F_CQE_SKIP;
+	io_notif_flush(zc->notif);
+	zc->notif = NULL;
+}
+
 int io_sendzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_sendzc *zc = io_kiocb_to_cmd(req, struct io_sendzc);
 	struct io_ring_ctx *ctx = req->ctx;
+	struct io_kiocb *notif;
 
-	if (READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3))
+	if (READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3) ||
+	    READ_ONCE(sqe->__pad3[0]))
+		return -EINVAL;
+	/* we don't support IOSQE_CQE_SKIP_SUCCESS just yet */
+	if (req->flags & REQ_F_CQE_SKIP)
 		return -EINVAL;
 
 	zc->flags = READ_ONCE(sqe->ioprio);
 	if (zc->flags & ~(IORING_RECVSEND_POLL_FIRST |
-			  IORING_RECVSEND_FIXED_BUF | IORING_RECVSEND_NOTIF_FLUSH))
+			  IORING_RECVSEND_FIXED_BUF))
 		return -EINVAL;
 	if (zc->flags & IORING_RECVSEND_FIXED_BUF) {
 		unsigned idx = READ_ONCE(sqe->buf_index);
@@ -900,11 +914,17 @@ int io_sendzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		req->imu = READ_ONCE(ctx->user_bufs[idx]);
 		io_req_set_rsrc_node(req, ctx, 0);
 	}
+	notif = zc->notif = io_alloc_notif(ctx);
+	if (!notif)
+		return -ENOMEM;
+	notif->cqe.user_data = req->cqe.user_data;
+	notif->cqe.res = 0;
+	notif->cqe.flags = IORING_CQE_F_NOTIF;
+	req->flags |= REQ_F_NEED_CLEANUP;
 
 	zc->buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
 	zc->len = READ_ONCE(sqe->len);
 	zc->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL;
-	zc->slot_idx = READ_ONCE(sqe->notification_idx);
 	if (zc->msg_flags & MSG_DONTWAIT)
 		req->flags |= REQ_F_NOWAIT;
 
@@ -956,7 +976,7 @@ static int io_sg_from_iter(struct sock *sk, struct sk_buff *skb,
 	shinfo->nr_frags = frag;
 	from->bvec += bi.bi_idx;
 	from->nr_segs -= bi.bi_idx;
-	from->count = bi.bi_size;
+	from->count -= copied;
 	from->iov_offset = bi.bi_bvec_done;
 
 	skb->data_len += copied;
@@ -976,33 +996,20 @@ static int io_sg_from_iter(struct sock *sk, struct sk_buff *skb,
 int io_sendzc(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct sockaddr_storage __address, *addr = NULL;
-	struct io_ring_ctx *ctx = req->ctx;
 	struct io_sendzc *zc = io_kiocb_to_cmd(req, struct io_sendzc);
-	struct io_notif_slot *notif_slot;
-	struct io_kiocb *notif;
 	struct msghdr msg;
 	struct iovec iov;
 	struct socket *sock;
-	unsigned msg_flags;
+	unsigned msg_flags, cflags;
 	int ret, min_ret = 0;
 
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (zc->flags & IORING_RECVSEND_POLL_FIRST))
 		return -EAGAIN;
-
-	if (issue_flags & IO_URING_F_UNLOCKED)
-		return -EAGAIN;
 	sock = sock_from_file(req->file);
 	if (unlikely(!sock))
 		return -ENOTSOCK;
 
-	notif_slot = io_get_notif_slot(ctx, zc->slot_idx);
-	if (!notif_slot)
-		return -EINVAL;
-	notif = io_get_notif(ctx, notif_slot);
-	if (!notif)
-		return -ENOMEM;
-
 	msg.msg_name = NULL;
 	msg.msg_control = NULL;
 	msg.msg_controllen = 0;
@@ -1033,7 +1040,7 @@ int io_sendzc(struct io_kiocb *req, unsigned int issue_flags)
 					  &msg.msg_iter);
 		if (unlikely(ret))
 			return ret;
-		ret = io_notif_account_mem(notif, zc->len);
+		ret = io_notif_account_mem(zc->notif, zc->len);
 		if (unlikely(ret))
 			return ret;
 	}
@@ -1045,7 +1052,7 @@ int io_sendzc(struct io_kiocb *req, unsigned int issue_flags)
 		min_ret = iov_iter_count(&msg.msg_iter);
 
 	msg.msg_flags = msg_flags;
-	msg.msg_ubuf = &io_notif_to_data(notif)->uarg;
+	msg.msg_ubuf = &io_notif_to_data(zc->notif)->uarg;
 	msg.sg_from_iter = io_sg_from_iter;
 	ret = sock_sendmsg(sock, &msg);
 
@@ -1060,18 +1067,22 @@ int io_sendzc(struct io_kiocb *req, unsigned int issue_flags)
 			req->flags |= REQ_F_PARTIAL_IO;
 			return io_setup_async_addr(req, addr, issue_flags);
 		}
+		if (ret < 0 && !zc->done_io)
+			zc->notif->flags |= REQ_F_CQE_SKIP;
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
 		req_set_fail(req);
-	} else if (zc->flags & IORING_RECVSEND_NOTIF_FLUSH) {
-		io_notif_slot_flush_submit(notif_slot, 0);
 	}
 
 	if (ret >= 0)
 		ret += zc->done_io;
 	else if (zc->done_io)
 		ret = zc->done_io;
-	io_req_set_res(req, ret, 0);
+
+	io_notif_flush(zc->notif);
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	cflags = ret >= 0 ? IORING_CQE_F_MORE : 0;
+	io_req_set_res(req, ret, cflags);
 	return IOU_OK;
 }
 
diff --git a/io_uring/net.h b/io_uring/net.h
index f91f56c6eeac..d744a0a874e7 100644
--- a/io_uring/net.h
+++ b/io_uring/net.h
@@ -55,6 +55,7 @@ int io_connect(struct io_kiocb *req, unsigned int issue_flags);
 
 int io_sendzc(struct io_kiocb *req, unsigned int issue_flags);
 int io_sendzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+void io_sendzc_cleanup(struct io_kiocb *req);
 
 void io_netmsg_cache_free(struct io_cache_entry *entry);
 #else
diff --git a/io_uring/notif.c b/io_uring/notif.c
index 96f076b175e0..38d77165edc3 100644
--- a/io_uring/notif.c
+++ b/io_uring/notif.c
@@ -42,8 +42,7 @@ static void io_uring_tx_zerocopy_callback(struct sk_buff *skb,
 	}
 }
 
-struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx,
-				struct io_notif_slot *slot)
+struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx)
 	__must_hold(&ctx->uring_lock)
 {
 	struct io_kiocb *notif;
@@ -59,101 +58,23 @@ struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx,
 	io_get_task_refs(1);
 	notif->rsrc_node = NULL;
 	io_req_set_rsrc_node(notif, ctx, 0);
-	notif->cqe.user_data = slot->tag;
-	notif->cqe.flags = slot->seq++;
-	notif->cqe.res = 0;
 
 	nd = io_notif_to_data(notif);
 	nd->account_pages = 0;
 	nd->uarg.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
 	nd->uarg.callback = io_uring_tx_zerocopy_callback;
-	/* master ref owned by io_notif_slot, will be dropped on flush */
 	refcount_set(&nd->uarg.refcnt, 1);
 	return notif;
 }
 
-void io_notif_slot_flush(struct io_notif_slot *slot)
+void io_notif_flush(struct io_kiocb *notif)
 	__must_hold(&slot->notif->ctx->uring_lock)
 {
-	struct io_kiocb *notif = slot->notif;
 	struct io_notif_data *nd = io_notif_to_data(notif);
 
-	slot->notif = NULL;
-
 	/* drop slot's master ref */
 	if (refcount_dec_and_test(&nd->uarg.refcnt)) {
 		notif->io_task_work.func = __io_notif_complete_tw;
 		io_req_task_work_add(notif);
 	}
 }
-
-__cold int io_notif_unregister(struct io_ring_ctx *ctx)
-	__must_hold(&ctx->uring_lock)
-{
-	int i;
-
-	if (!ctx->notif_slots)
-		return -ENXIO;
-
-	for (i = 0; i < ctx->nr_notif_slots; i++) {
-		struct io_notif_slot *slot = &ctx->notif_slots[i];
-		struct io_kiocb *notif = slot->notif;
-		struct io_notif_data *nd;
-
-		if (!notif)
-			continue;
-		nd = io_notif_to_data(notif);
-		slot->notif = NULL;
-		if (!refcount_dec_and_test(&nd->uarg.refcnt))
-			continue;
-		notif->io_task_work.func = __io_notif_complete_tw;
-		io_req_task_work_add(notif);
-	}
-
-	kvfree(ctx->notif_slots);
-	ctx->notif_slots = NULL;
-	ctx->nr_notif_slots = 0;
-	return 0;
-}
-
-__cold int io_notif_register(struct io_ring_ctx *ctx,
-			     void __user *arg, unsigned int size)
-	__must_hold(&ctx->uring_lock)
-{
-	struct io_uring_notification_slot __user *slots;
-	struct io_uring_notification_slot slot;
-	struct io_uring_notification_register reg;
-	unsigned i;
-
-	if (ctx->nr_notif_slots)
-		return -EBUSY;
-	if (size != sizeof(reg))
-		return -EINVAL;
-	if (copy_from_user(&reg, arg, sizeof(reg)))
-		return -EFAULT;
-	if (!reg.nr_slots || reg.nr_slots > IORING_MAX_NOTIF_SLOTS)
-		return -EINVAL;
-	if (reg.resv || reg.resv2 || reg.resv3)
-		return -EINVAL;
-
-	slots = u64_to_user_ptr(reg.data);
-	ctx->notif_slots = kvcalloc(reg.nr_slots, sizeof(ctx->notif_slots[0]),
-				GFP_KERNEL_ACCOUNT);
-	if (!ctx->notif_slots)
-		return -ENOMEM;
-
-	for (i = 0; i < reg.nr_slots; i++, ctx->nr_notif_slots++) {
-		struct io_notif_slot *notif_slot = &ctx->notif_slots[i];
-
-		if (copy_from_user(&slot, &slots[i], sizeof(slot))) {
-			io_notif_unregister(ctx);
-			return -EFAULT;
-		}
-		if (slot.resv[0] | slot.resv[1] | slot.resv[2]) {
-			io_notif_unregister(ctx);
-			return -EINVAL;
-		}
-		notif_slot->tag = slot.tag;
-	}
-	return 0;
-}
diff --git a/io_uring/notif.h b/io_uring/notif.h
index 80f6445e0c2b..5b4d710c8ca5 100644
--- a/io_uring/notif.h
+++ b/io_uring/notif.h
@@ -8,7 +8,6 @@
 #include "rsrc.h"
 
 #define IO_NOTIF_SPLICE_BATCH	32
-#define IORING_MAX_NOTIF_SLOTS	(1U << 15)
 
 struct io_notif_data {
 	struct file		*file;
@@ -16,63 +15,14 @@ struct io_notif_data {
 	unsigned long		account_pages;
 };
 
-struct io_notif_slot {
-	/*
-	 * Current/active notifier. A slot holds only one active notifier at a
-	 * time and keeps one reference to it. Flush releases the reference and
-	 * lazily replaces it with a new notifier.
-	 */
-	struct io_kiocb		*notif;
-
-	/*
-	 * Default ->user_data for this slot notifiers CQEs
-	 */
-	u64			tag;
-	/*
-	 * Notifiers of a slot live in generations, we create a new notifier
-	 * only after flushing the previous one. Track the sequential number
-	 * for all notifiers and copy it into notifiers's cqe->cflags
-	 */
-	u32			seq;
-};
-
-int io_notif_register(struct io_ring_ctx *ctx,
-		      void __user *arg, unsigned int size);
-int io_notif_unregister(struct io_ring_ctx *ctx);
-
-void io_notif_slot_flush(struct io_notif_slot *slot);
-struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx,
-				struct io_notif_slot *slot);
+void io_notif_flush(struct io_kiocb *notif);
+struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx);
 
 static inline struct io_notif_data *io_notif_to_data(struct io_kiocb *notif)
 {
 	return io_kiocb_to_cmd(notif, struct io_notif_data);
 }
 
-static inline struct io_kiocb *io_get_notif(struct io_ring_ctx *ctx,
-					    struct io_notif_slot *slot)
-{
-	if (!slot->notif)
-		slot->notif = io_alloc_notif(ctx, slot);
-	return slot->notif;
-}
-
-static inline struct io_notif_slot *io_get_notif_slot(struct io_ring_ctx *ctx,
-						      unsigned idx)
-	__must_hold(&ctx->uring_lock)
-{
-	if (idx >= ctx->nr_notif_slots)
-		return NULL;
-	idx = array_index_nospec(idx, ctx->nr_notif_slots);
-	return &ctx->notif_slots[idx];
-}
-
-static inline void io_notif_slot_flush_submit(struct io_notif_slot *slot,
-					      unsigned int issue_flags)
-{
-	io_notif_slot_flush(slot);
-}
-
 static inline int io_notif_account_mem(struct io_kiocb *notif, unsigned len)
 {
 	struct io_ring_ctx *ctx = notif->ctx;
diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index 41410126c1c6..c61494e0a602 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -246,13 +246,12 @@ const struct io_op_def io_op_defs[] = {
 		.prep			= io_close_prep,
 		.issue			= io_close,
 	},
-	[IORING_OP_RSRC_UPDATE] = {
+	[IORING_OP_FILES_UPDATE] = {
 		.audit_skip		= 1,
 		.iopoll			= 1,
-		.name			= "RSRC_UPDATE",
-		.prep			= io_rsrc_update_prep,
-		.issue			= io_rsrc_update,
-		.ioprio			= 1,
+		.name			= "FILES_UPDATE",
+		.prep			= io_files_update_prep,
+		.issue			= io_files_update,
 	},
 	[IORING_OP_STATX] = {
 		.audit_skip		= 1,
@@ -471,7 +470,7 @@ const struct io_op_def io_op_defs[] = {
 		.issue			= io_uring_cmd,
 		.prep_async		= io_uring_cmd_prep_async,
 	},
-	[IORING_OP_SENDZC_NOTIF] = {
+	[IORING_OP_SEND_ZC] = {
 		.name			= "SENDZC_NOTIF",
 		.needs_file		= 1,
 		.unbound_nonreg_file	= 1,
@@ -484,6 +483,7 @@ const struct io_op_def io_op_defs[] = {
 		.prep			= io_sendzc_prep,
 		.issue			= io_sendzc,
 		.prep_async		= io_sendzc_prep_async,
+		.cleanup		= io_sendzc_cleanup,
 #else
 		.prep			= io_eopnotsupp_prep,
 #endif
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 71359a4d0bd4..cf3272113214 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -15,14 +15,12 @@
 #include "io_uring.h"
 #include "openclose.h"
 #include "rsrc.h"
-#include "notif.h"
 
 struct io_rsrc_update {
 	struct file			*file;
 	u64				arg;
 	u32				nr_args;
 	u32				offset;
-	int				type;
 };
 
 static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
@@ -655,7 +653,7 @@ __cold int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg,
 	return -EINVAL;
 }
 
-int io_rsrc_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+int io_files_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 
@@ -669,7 +667,6 @@ int io_rsrc_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (!up->nr_args)
 		return -EINVAL;
 	up->arg = READ_ONCE(sqe->addr);
-	up->type = READ_ONCE(sqe->ioprio);
 	return 0;
 }
 
@@ -712,7 +709,7 @@ static int io_files_update_with_index_alloc(struct io_kiocb *req,
 	return ret;
 }
 
-static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
+int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 	struct io_ring_ctx *ctx = req->ctx;
@@ -741,54 +738,6 @@ static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 	return IOU_OK;
 }
 
-static int io_notif_update(struct io_kiocb *req, unsigned int issue_flags)
-{
-	struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
-	struct io_ring_ctx *ctx = req->ctx;
-	unsigned len = up->nr_args;
-	unsigned idx_end, idx = up->offset;
-	int ret = 0;
-
-	io_ring_submit_lock(ctx, issue_flags);
-	if (unlikely(check_add_overflow(idx, len, &idx_end))) {
-		ret = -EOVERFLOW;
-		goto out;
-	}
-	if (unlikely(idx_end > ctx->nr_notif_slots)) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	for (; idx < idx_end; idx++) {
-		struct io_notif_slot *slot = &ctx->notif_slots[idx];
-
-		if (!slot->notif)
-			continue;
-		if (up->arg)
-			slot->tag = up->arg;
-		io_notif_slot_flush_submit(slot, issue_flags);
-	}
-out:
-	io_ring_submit_unlock(ctx, issue_flags);
-	if (ret < 0)
-		req_set_fail(req);
-	io_req_set_res(req, ret, 0);
-	return IOU_OK;
-}
-
-int io_rsrc_update(struct io_kiocb *req, unsigned int issue_flags)
-{
-	struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
-
-	switch (up->type) {
-	case IORING_RSRC_UPDATE_FILES:
-		return io_files_update(req, issue_flags);
-	case IORING_RSRC_UPDATE_NOTIF:
-		return io_notif_update(req, issue_flags);
-	}
-	return -EINVAL;
-}
-
 int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx,
 			  struct io_rsrc_node *node, void *rsrc)
 {
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index f3a9a177941f..9bce15665444 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -167,8 +167,8 @@ static inline u64 *io_get_tag_slot(struct io_rsrc_data *data, unsigned int idx)
 	return &data->tags[table_idx][off];
 }
 
-int io_rsrc_update(struct io_kiocb *req, unsigned int issue_flags);
-int io_rsrc_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_files_update(struct io_kiocb *req, unsigned int issue_flags);
+int io_files_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 
 int __io_account_mem(struct user_struct *user, unsigned long nr_pages);