public inbox for [email protected]
 help / color / mirror / Atom feed
From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH v3 07/17] io_uring: ctx-wide rsrc nodes
Date: Thu, 25 Mar 2021 13:07:56 +0000	[thread overview]
Message-ID: <51c5e836791a3faf46d996e403f9ca4241d7951b.1616677487.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>

If we're going to ever support multiple types of resources we need
shared rsrc nodes to not bloat requests, that is implemented in this
patch. It also gives a nicer API and saves one pointer dereference
in io_req_set_rsrc_node().

We may say that all requests bound to a resource belong to one and only
one rsrc node, and considering that nodes are removed and recycled
strictly in-order, this separates requests into generations, where
generation are changed on each node switch (i.e. io_rsrc_node_switch()).

The API is simple, io_rsrc_node_switch() switches to a new generation if
needed, and also optionally kills a passed in io_rsrc_data. Each call to
io_rsrc_node_switch() have to be preceded with
io_rsrc_node_switch_start(). The start function is idempotent and should
not necessarily be followed by switch.

One difference is that once a node was set it will always retain a valid
rsrc node, even on unregister. It may be a nuisance at the moment, but
makes much sense for multiple types of resources. Another thing changed
is that nodes are bound to/associated with a io_rsrc_data later just
before killing (i.e. switching).

Signed-off-by: Pavel Begunkov <[email protected]>
---
 fs/io_uring.c | 73 ++++++++++++++++++++++++++-------------------------
 1 file changed, 37 insertions(+), 36 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6d2e3a3c202e..1328ff24d557 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -231,7 +231,6 @@ struct io_rsrc_data {
 	struct io_ring_ctx		*ctx;
 
 	rsrc_put_fn			*do_put;
-	struct io_rsrc_node		*node;
 	struct percpu_ref		refs;
 	struct completion		done;
 	bool				quiesce;
@@ -444,6 +443,7 @@ struct io_ring_ctx {
 	struct llist_head		rsrc_put_llist;
 	struct list_head		rsrc_ref_list;
 	spinlock_t			rsrc_ref_lock;
+	struct io_rsrc_node		*rsrc_node;
 	struct io_rsrc_node		*rsrc_backup_node;
 
 	struct io_restriction		restrictions;
@@ -1064,7 +1064,7 @@ static inline void io_req_set_rsrc_node(struct io_kiocb *req)
 	struct io_ring_ctx *ctx = req->ctx;
 
 	if (!req->fixed_rsrc_refs) {
-		req->fixed_rsrc_refs = &ctx->file_data->node->refs;
+		req->fixed_rsrc_refs = &ctx->rsrc_node->refs;
 		percpu_ref_get(req->fixed_rsrc_refs);
 	}
 }
@@ -6963,36 +6963,32 @@ static inline void io_rsrc_ref_unlock(struct io_ring_ctx *ctx)
 	spin_unlock_bh(&ctx->rsrc_ref_lock);
 }
 
-static void io_rsrc_node_set(struct io_ring_ctx *ctx,
-			     struct io_rsrc_data *rsrc_data)
+static void io_rsrc_node_switch(struct io_ring_ctx *ctx,
+				struct io_rsrc_data *data_to_kill)
 {
-	struct io_rsrc_node *rsrc_node = ctx->rsrc_backup_node;
+	WARN_ON_ONCE(!ctx->rsrc_backup_node);
+	WARN_ON_ONCE(data_to_kill && !ctx->rsrc_node);
 
-	WARN_ON_ONCE(!rsrc_node);
+	if (data_to_kill) {
+		struct io_rsrc_node *rsrc_node = ctx->rsrc_node;
 
-	ctx->rsrc_backup_node = NULL;
-	rsrc_node->rsrc_data = rsrc_data;
+		rsrc_node->rsrc_data = data_to_kill;
+		io_rsrc_ref_lock(ctx);
+		list_add_tail(&rsrc_node->node, &ctx->rsrc_ref_list);
+		io_rsrc_ref_unlock(ctx);
 
-	io_rsrc_ref_lock(ctx);
-	rsrc_data->node = rsrc_node;
-	list_add_tail(&rsrc_node->node, &ctx->rsrc_ref_list);
-	io_rsrc_ref_unlock(ctx);
-	percpu_ref_get(&rsrc_data->refs);
-}
-
-static void io_rsrc_node_kill(struct io_ring_ctx *ctx, struct io_rsrc_data *data)
-{
-	struct io_rsrc_node *ref_node = NULL;
+		percpu_ref_get(&data_to_kill->refs);
+		percpu_ref_kill(&rsrc_node->refs);
+		ctx->rsrc_node = NULL;
+	}
 
-	io_rsrc_ref_lock(ctx);
-	ref_node = data->node;
-	data->node = NULL;
-	io_rsrc_ref_unlock(ctx);
-	if (ref_node)
-		percpu_ref_kill(&ref_node->refs);
+	if (!ctx->rsrc_node) {
+		ctx->rsrc_node = ctx->rsrc_backup_node;
+		ctx->rsrc_backup_node = NULL;
+	}
 }
 
-static int io_rsrc_node_prealloc(struct io_ring_ctx *ctx)
+static int io_rsrc_node_switch_start(struct io_ring_ctx *ctx)
 {
 	if (ctx->rsrc_backup_node)
 		return 0;
@@ -7009,10 +7005,11 @@ static int io_rsrc_ref_quiesce(struct io_rsrc_data *data, struct io_ring_ctx *ct
 
 	data->quiesce = true;
 	do {
-		ret = io_rsrc_node_prealloc(ctx);
+		ret = io_rsrc_node_switch_start(ctx);
 		if (ret)
 			break;
-		io_rsrc_node_kill(ctx, data);
+		io_rsrc_node_switch(ctx, data);
+
 		percpu_ref_kill(&data->refs);
 		flush_delayed_work(&ctx->rsrc_put_work);
 
@@ -7021,7 +7018,6 @@ static int io_rsrc_ref_quiesce(struct io_rsrc_data *data, struct io_ring_ctx *ct
 			break;
 
 		percpu_ref_resurrect(&data->refs);
-		io_rsrc_node_set(ctx, data);
 		reinit_completion(&data->done);
 
 		mutex_unlock(&ctx->uring_lock);
@@ -7502,7 +7498,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 		return -EINVAL;
 	if (nr_args > IORING_MAX_FIXED_FILES)
 		return -EMFILE;
-	ret = io_rsrc_node_prealloc(ctx);
+	ret = io_rsrc_node_switch_start(ctx);
 	if (ret)
 		return ret;
 
@@ -7564,7 +7560,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 		return ret;
 	}
 
-	io_rsrc_node_set(ctx, file_data);
+	io_rsrc_node_switch(ctx, NULL);
 	return ret;
 out_fput:
 	for (i = 0; i < ctx->nr_user_files; i++) {
@@ -7653,7 +7649,7 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 		return -EOVERFLOW;
 	if (done > ctx->nr_user_files)
 		return -EINVAL;
-	err = io_rsrc_node_prealloc(ctx);
+	err = io_rsrc_node_switch_start(ctx);
 	if (err)
 		return err;
 
@@ -7672,7 +7668,7 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 
 		if (*file_slot) {
 			file = (struct file *) ((unsigned long) *file_slot & FFS_MASK);
-			err = io_queue_rsrc_removal(data, data->node, file);
+			err = io_queue_rsrc_removal(data, ctx->rsrc_node, file);
 			if (err)
 				break;
 			*file_slot = NULL;
@@ -7707,10 +7703,8 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 		}
 	}
 
-	if (needs_switch) {
-		percpu_ref_kill(&data->node->refs);
-		io_rsrc_node_set(ctx, data);
-	}
+	if (needs_switch)
+		io_rsrc_node_switch(ctx, data);
 	return done ? done : err;
 }
 
@@ -8386,8 +8380,15 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	io_eventfd_unregister(ctx);
 	io_destroy_buffers(ctx);
 
+	/* there are no registered resources left, nobody uses it */
+	if (ctx->rsrc_node)
+		io_rsrc_node_destroy(ctx->rsrc_node);
 	if (ctx->rsrc_backup_node)
 		io_rsrc_node_destroy(ctx->rsrc_backup_node);
+	flush_delayed_work(&ctx->rsrc_put_work);
+
+	WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list));
+	WARN_ON_ONCE(!llist_empty(&ctx->rsrc_put_llist));
 
 #if defined(CONFIG_UNIX)
 	if (ctx->ring_sock) {
-- 
2.24.0


  parent reply	other threads:[~2021-03-25 13:13 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-25 13:07 [PATCH v3 for-5.13 00/17] ctx wide rsrc nodes + other stuff Pavel Begunkov
2021-03-25 13:07 ` [PATCH v3 01/17] io_uring: name rsrc bits consistently Pavel Begunkov
2021-03-25 13:07 ` [PATCH v3 02/17] io_uring: simplify io_rsrc_node_ref_zero Pavel Begunkov
2021-03-25 13:07 ` [PATCH v3 03/17] io_uring: use rsrc prealloc infra for files reg Pavel Begunkov
2021-03-25 13:07 ` [PATCH v3 04/17] io_uring: encapsulate rsrc node manipulations Pavel Begunkov
2021-03-25 13:07 ` [PATCH v3 05/17] io_uring: move rsrc_put callback into io_rsrc_data Pavel Begunkov
2021-03-25 13:07 ` [PATCH v3 06/17] io_uring: refactor io_queue_rsrc_removal() Pavel Begunkov
2021-03-25 13:07 ` Pavel Begunkov [this message]
2021-03-25 13:07 ` [PATCH v3 08/17] io_uring: reuse io_rsrc_node_destroy() Pavel Begunkov
2021-03-25 13:07 ` [PATCH v3 09/17] io_uring: remove useless is_dying check on quiesce Pavel Begunkov
2021-03-25 13:07 ` [PATCH v3 10/17] io_uring: refactor rw reissue Pavel Begunkov
2021-03-25 13:08 ` [PATCH v3 11/17] io_uring: combine lock/unlock sections on exit Pavel Begunkov
2021-03-25 13:08 ` [PATCH v3 12/17] io_uring: better ref handling in poll_remove_one Pavel Begunkov
2021-03-25 13:08 ` [PATCH v3 13/17] io_uring: remove unused hash_wait Pavel Begunkov
2021-03-25 13:08 ` [PATCH v3 14/17] io_uring: refactor io_async_cancel() Pavel Begunkov
2021-03-25 13:08 ` [PATCH v3 15/17] io_uring: improve import_fixed overflow checks Pavel Begunkov
2021-03-25 13:08 ` [PATCH v3 16/17] io_uring: store reg buffer end instead of length Pavel Begunkov
2021-03-25 13:08 ` [PATCH v3 17/17] io_uring: kill unused forward decls Pavel Begunkov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=51c5e836791a3faf46d996e403f9ca4241d7951b.1616677487.git.asml.silence@gmail.com \
    [email protected] \
    [email protected] \
    [email protected] \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox