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From: Matt Mullins <mmullins@fb.com>
To: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-aio@kvack.org" <linux-aio@kvack.org>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
	"axboe@kernel.dk" <axboe@kernel.dk>
Cc: "hch@lst.de" <hch@lst.de>, "jannh@google.com" <jannh@google.com>,
	"viro@ZenIV.linux.org.uk" <viro@ZenIV.linux.org.uk>,
	"avi@scylladb.com" <avi@scylladb.com>,
	"jmoyer@redhat.com" <jmoyer@redhat.com>
Subject: Re: [PATCH 14/19] io_uring: add file set registration
Date: Sat, 9 Feb 2019 23:52:24 +0000
Message-ID: <f722cc1a73bd7615d71fb020e87e5439f59947d7.camel@fb.com> (raw)
In-Reply-To: <20190209211346.26060-15-axboe@kernel.dk>

On Sat, 2019-02-09 at 14:13 -0700, Jens Axboe wrote:
> We normally have to fget/fput for each IO we do on a file. Even with
> the batching we do, the cost of the atomic inc/dec of the file usage
> count adds up.
> 
> This adds IORING_REGISTER_FILES, and IORING_UNREGISTER_FILES opcodes
> for the io_uring_register(2) system call. The arguments passed in must
> be an array of __s32 holding file descriptors, and nr_args should hold
> the number of file descriptors the application wishes to pin for the
> duration of the io_uring instance (or until IORING_UNREGISTER_FILES is
> called).
> 
> When used, the application must set IOSQE_FIXED_FILE in the sqe->flags
> member. Then, instead of setting sqe->fd to the real fd, it sets sqe->fd
> to the index in the array passed in to IORING_REGISTER_FILES.
> 
> Files are automatically unregistered when the io_uring instance is torn
> down. An application need only unregister if it wishes to register a new
> set of fds.
> 
> Reviewed-by: Hannes Reinecke <hare@suse.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  fs/io_uring.c                 | 269 ++++++++++++++++++++++++++++++----
>  include/uapi/linux/io_uring.h |   9 +-
>  2 files changed, 245 insertions(+), 33 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 09a3122b3b6c..c40a7ed2edd5 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -29,6 +29,7 @@
>  #include <linux/net.h>
>  #include <net/sock.h>
>  #include <net/af_unix.h>
> +#include <net/scm.h>
>  #include <linux/anon_inodes.h>
>  #include <linux/sched/mm.h>
>  #include <linux/uaccess.h>
> @@ -41,6 +42,7 @@
>  #include "internal.h"
>  
>  #define IORING_MAX_ENTRIES	4096
> +#define IORING_MAX_FIXED_FILES	1024
>  
>  struct io_uring {
>  	u32 head ____cacheline_aligned_in_smp;
> @@ -103,6 +105,14 @@ struct io_ring_ctx {
>  		struct fasync_struct	*cq_fasync;
>  	} ____cacheline_aligned_in_smp;
>  
> +	/*
> +	 * If used, fixed file set. Writers must ensure that ->refs is dead,
> +	 * readers must ensure that ->refs is alive as long as the file* is
> +	 * used. Only updated through io_uring_register(2).
> +	 */
> +	struct file		**user_files;
> +	unsigned		nr_user_files;
> +
>  	/* if used, fixed mapped user buffers */
>  	unsigned		nr_user_bufs;
>  	struct io_mapped_ubuf	*user_bufs;
> @@ -150,6 +160,7 @@ struct io_kiocb {
>  	unsigned int		flags;
>  #define REQ_F_FORCE_NONBLOCK	1	/* inline submission attempt */
>  #define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
> +#define REQ_F_FIXED_FILE	4	/* ctx owns file */
>  	u64			user_data;
>  	u64			error;
>  
> @@ -380,15 +391,17 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
>  		 * Batched puts of the same file, to avoid dirtying the
>  		 * file usage count multiple times, if avoidable.
>  		 */
> -		if (!file) {
> -			file = req->rw.ki_filp;
> -			file_count = 1;
> -		} else if (file == req->rw.ki_filp) {
> -			file_count++;
> -		} else {
> -			fput_many(file, file_count);
> -			file = req->rw.ki_filp;
> -			file_count = 1;
> +		if (!(req->flags & REQ_F_FIXED_FILE)) {
> +			if (!file) {
> +				file = req->rw.ki_filp;
> +				file_count = 1;
> +			} else if (file == req->rw.ki_filp) {
> +				file_count++;
> +			} else {
> +				fput_many(file, file_count);
> +				file = req->rw.ki_filp;
> +				file_count = 1;
> +			}
>  		}
>  
>  		if (to_free == ARRAY_SIZE(reqs))
> @@ -520,13 +533,19 @@ static void kiocb_end_write(struct kiocb *kiocb)
>  	}
>  }
>  
> +static void io_fput(struct io_kiocb *req)
> +{
> +	if (!(req->flags & REQ_F_FIXED_FILE))
> +		fput(req->rw.ki_filp);
> +}
> +
>  static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
>  {
>  	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
>  
>  	kiocb_end_write(kiocb);
>  
> -	fput(kiocb->ki_filp);
> +	io_fput(req);
>  	io_cqring_add_event(req->ctx, req->user_data, res, 0);
>  	io_free_req(req);
>  }
> @@ -642,19 +661,29 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
>  {
>  	struct io_ring_ctx *ctx = req->ctx;
>  	struct kiocb *kiocb = &req->rw;
> -	unsigned ioprio;
> +	unsigned ioprio, flags;
>  	int fd, ret;
>  
>  	/* For -EAGAIN retry, everything is already prepped */
>  	if (kiocb->ki_filp)
>  		return 0;
>  
> +	flags = READ_ONCE(sqe->flags);
>  	fd = READ_ONCE(sqe->fd);
> -	kiocb->ki_filp = io_file_get(state, fd);
> -	if (unlikely(!kiocb->ki_filp))
> -		return -EBADF;
> -	if (force_nonblock && !io_file_supports_async(kiocb->ki_filp))
> -		force_nonblock = false;
> +
> +	if (flags & IOSQE_FIXED_FILE) {
> +		if (unlikely(!ctx->user_files ||
> +		    (unsigned) fd >= ctx->nr_user_files))
> +			return -EBADF;
> +		kiocb->ki_filp = ctx->user_files[fd];
> +		req->flags |= REQ_F_FIXED_FILE;
> +	} else {
> +		kiocb->ki_filp = io_file_get(state, fd);
> +		if (unlikely(!kiocb->ki_filp))
> +			return -EBADF;
> +		if (force_nonblock && !io_file_supports_async(kiocb->ki_filp))
> +			force_nonblock = false;
> +	}
>  	kiocb->ki_pos = READ_ONCE(sqe->off);
>  	kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
>  	kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
> @@ -694,10 +723,14 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
>  	}
>  	return 0;
>  out_fput:
> -	/* in case of error, we didn't use this file reference. drop it. */
> -	if (state)
> -		state->used_refs--;
> -	io_file_put(state, kiocb->ki_filp);
> +	if (!(flags & IOSQE_FIXED_FILE)) {
> +		/*
> +		 * in case of error, we didn't use this file reference. drop it.
> +		 */
> +		if (state)
> +			state->used_refs--;
> +		io_file_put(state, kiocb->ki_filp);
> +	}
>  	return ret;
>  }
>  
> @@ -837,7 +870,7 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
>  out_fput:
>  	/* Hold on to the file for -EAGAIN */
>  	if (unlikely(ret && ret != -EAGAIN))
> -		fput(file);
> +		io_fput(req);
>  	return ret;
>  }
>  
> @@ -891,7 +924,7 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
>  	kfree(iovec);
>  out_fput:
>  	if (unlikely(ret))
> -		fput(file);
> +		io_fput(req);
>  	return ret;
>  }
>  
> @@ -914,7 +947,8 @@ static int io_nop(struct io_kiocb *req, u64 user_data)
>  	 */
>  	if (req->rw.ki_filp) {
>  		err = -EBADF;
> -		fput(req->rw.ki_filp);
> +		if (!(req->flags & REQ_F_FIXED_FILE))
> +			fput(req->rw.ki_filp);
>  	}
>  	io_cqring_add_event(ctx, user_data, err, 0);
>  	io_free_req(req);
> @@ -923,21 +957,32 @@ static int io_nop(struct io_kiocb *req, u64 user_data)
>  
>  static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  {
> +	struct io_ring_ctx *ctx = req->ctx;
> +	unsigned flags;
>  	int fd;
>  
>  	/* Prep already done */
>  	if (req->rw.ki_filp)
>  		return 0;
>  
> -	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
> +	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
>  		return -EINVAL;
>  	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
>  		return -EINVAL;
>  
>  	fd = READ_ONCE(sqe->fd);
> -	req->rw.ki_filp = fget(fd);
> -	if (unlikely(!req->rw.ki_filp))
> -		return -EBADF;
> +	flags = READ_ONCE(sqe->flags);
> +
> +	if (flags & IOSQE_FIXED_FILE) {
> +		if (unlikely(!ctx->user_files || fd >= ctx->nr_user_files))
> +			return -EBADF;
> +		req->rw.ki_filp = ctx->user_files[fd];
> +		req->flags |= REQ_F_FIXED_FILE;
> +	} else {
> +		req->rw.ki_filp = fget(fd);
> +		if (unlikely(!req->rw.ki_filp))
> +			return -EBADF;
> +	}
>  
>  	return 0;
>  }
> @@ -967,7 +1012,8 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
>  				end > 0 ? end : LLONG_MAX,
>  				fsync_flags & IORING_FSYNC_DATASYNC);
>  
> -	fput(req->rw.ki_filp);
> +	if (!(req->flags & REQ_F_FIXED_FILE))
> +		fput(req->rw.ki_filp);
>  	io_cqring_add_event(req->ctx, sqe->user_data, ret, 0);
>  	io_free_req(req);
>  	return 0;
> @@ -1104,7 +1150,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s,
>  	ssize_t ret;
>  
>  	/* enforce forwards compatibility on users */
> -	if (unlikely(s->sqe->flags))
> +	if (unlikely(s->sqe->flags & ~IOSQE_FIXED_FILE))
>  		return -EINVAL;
>  
>  	req = io_get_req(ctx, state);
> @@ -1292,6 +1338,154 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
>  	return READ_ONCE(ring->r.head) == READ_ONCE(ring->r.tail) ? ret : 0;
>  }
>  
> +static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
> +{
> +#if defined(CONFIG_UNIX)
> +	if (ctx->ring_sock) {
> +		struct sock *sock = ctx->ring_sock->sk;
> +		struct sk_buff *skb;
> +
> +		while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)

Something's still a bit messy with destruction.  I get a traceback here
while running

  int main() {
    struct io_uring_params uring_params = {
        .flags = IORING_SETUP_SQPOLL | IORING_SETUP_IOPOLL,
    };
    int uring_fd = 
        syscall(425 /* io_uring_setup */, 16, &uring_params);
    
    const __s32 fds[] = {1};
    
    syscall(427 /* io_uring_register */, uring_fd,
            IORING_REGISTER_FILES, fds, sizeof(fds) / sizeof(*fds));
  }

I end up with the following spew:

[  195.983322] WARNING: CPU: 1 PID: 1938 at ../net/unix/af_unix.c:500 unix_sock_destructor+0x97/0xc0
[  195.989556] Modules linked in:
[  195.992738] CPU: 1 PID: 1938 Comm: aio_buffered Tainted: G        W         5.0.0-rc5+ #379
[  196.000926] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[  196.008316] RIP: 0010:unix_sock_destructor+0x97/0xc0
[  196.010912] Code: 3f 37 f3 ff 5b 5d be 00 02 00 00 48 c7 c7 6c 5b 9a 81 e9 8c 2a 71 ff 48 89 ef e8 c4 dc 87 ff eb be 0f 0b 48 83 7b 70 00 74 8b <0f> 0b 48 83 bb 68 02 00 00 00 74 89 0f 0b eb 85 48 89 de 48 c7 c7
[  196.018887] RSP: 0018:ffffc900008a7d40 EFLAGS: 00010282
[  196.020754] RAX: 0000000000000000 RBX: ffff8881351dd000 RCX: 0000000000000000
[  196.022811] RDX: 0000000000000001 RSI: 0000000000000282 RDI: 00000000ffffffff
[  196.024901] RBP: ffff8881351dd000 R08: 0000000000024120 R09: ffffffff819a97fe
[  196.026977] R10: ffffea0004cf6800 R11: 00000000005b8d80 R12: ffffffff81294ec2
[  196.029119] R13: ffff888134e27b40 R14: ffff88813bb307a0 R15: ffff888133d59910
[  196.031071] FS:  00007f1a8a8c3740(0000) GS:ffff88813bb00000(0000) knlGS:0000000000000000
[  196.033069] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  196.034438] CR2: 00007f1a8aba5920 CR3: 000000000260e004 CR4: 00000000003606a0
[  196.036310] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  196.038399] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  196.039794] Call Trace:
[  196.040259]  __sk_destruct+0x1c/0x150
[  196.040964]  ? io_sqe_files_unregister+0x32/0x70
[  196.041841]  unix_destruct_scm+0x76/0xa0
[  196.042587]  skb_release_head_state+0x38/0x60
[  196.043401]  skb_release_all+0x9/0x20
[  196.044034]  kfree_skb+0x2d/0xb0
[  196.044603]  io_sqe_files_unregister+0x32/0x70
[  196.045385]  io_ring_ctx_wait_and_kill+0xf6/0x1a0
[  196.046220]  io_uring_release+0x17/0x20
[  196.046881]  __fput+0x9d/0x1d0
[  196.047421]  task_work_run+0x7a/0x90
[  196.048045]  do_exit+0x301/0xc20
[  196.048626]  ? handle_mm_fault+0xf3/0x230
[  196.049321]  do_group_exit+0x35/0xa0
[  196.049944]  __x64_sys_exit_group+0xf/0x10
[  196.050658]  do_syscall_64+0x3d/0xf0
[  196.051317]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  196.052217] RIP: 0033:0x7f1a8aba5956
[  196.052859] Code: Bad RIP value.
[  196.053488] RSP: 002b:00007fffbdbcad38 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[  196.054902] RAX: ffffffffffffffda RBX: 00007f1a8ac975c0 RCX: 00007f1a8aba5956
[  196.056124] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
[  196.057348] RBP: 0000000000000000 R08: 00000000000000e7 R09: ffffffffffffff78
[  196.058573] R10: 00007fffbdbcabf8 R11: 0000000000000246 R12: 00007f1a8ac975c0
[  196.059459] R13: 0000000000000001 R14: 00007f1a8aca0288 R15: 0000000000000000
[  196.060731] ---[ end trace 8a7e42f9199e5f92 ]---
[  196.062671] WARNING: CPU: 1 PID: 1938 at ../net/unix/af_unix.c:501 unix_sock_destructor+0xa3/0xc0
[  196.064372] Modules linked in:
[  196.064966] CPU: 1 PID: 1938 Comm: aio_buffered Tainted: G        W         5.0.0-rc5+ #379
[  196.066546] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[  196.068234] RIP: 0010:unix_sock_destructor+0xa3/0xc0
[  196.068999] Code: c7 c7 6c 5b 9a 81 e9 8c 2a 71 ff 48 89 ef e8 c4 dc 87 ff eb be 0f 0b 48 83 7b 70 00 74 8b 0f 0b 48 83 bb 68 02 00 00 00 74 89 <0f> 0b eb 85 48 89 de 48 c7 c7 a0 c8 42 82 5b 5d e9 31 8c 75 ff 0f
[  196.072577] RSP: 0018:ffffc900008a7d40 EFLAGS: 00010282
[  196.073595] RAX: 0000000000000000 RBX: ffff8881351dd000 RCX: 0000000000000000
[  196.074973] RDX: 0000000000000001 RSI: 0000000000000282 RDI: 00000000ffffffff
[  196.076348] RBP: ffff8881351dd000 R08: 0000000000024120 R09: ffffffff819a97fe
[  196.077709] R10: ffffea0004cf6800 R11: 00000000005b8d80 R12: ffffffff81294ec2
[  196.079072] R13: ffff888134e27b40 R14: ffff88813bb307a0 R15: ffff888133d59910
[  196.080441] FS:  00007f1a8a8c3740(0000) GS:ffff88813bb00000(0000) knlGS:0000000000000000
[  196.082026] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  196.083131] CR2: 00007fbc19f96550 CR3: 0000000138d1e003 CR4: 00000000003606a0
[  196.084505] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  196.085823] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  196.087185] Call Trace:
[  196.087662]  __sk_destruct+0x1c/0x150
[  196.088376]  ? io_sqe_files_unregister+0x32/0x70
[  196.089299]  unix_destruct_scm+0x76/0xa0
[  196.090059]  skb_release_head_state+0x38/0x60
[  196.090929]  skb_release_all+0x9/0x20
[  196.091550]  kfree_skb+0x2d/0xb0
[  196.092745]  io_sqe_files_unregister+0x32/0x70
[  196.093535]  io_ring_ctx_wait_and_kill+0xf6/0x1a0
[  196.094358]  io_uring_release+0x17/0x20
[  196.095029]  __fput+0x9d/0x1d0
[  196.095660]  task_work_run+0x7a/0x90
[  196.096307]  do_exit+0x301/0xc20
[  196.096808]  ? handle_mm_fault+0xf3/0x230
[  196.097504]  do_group_exit+0x35/0xa0
[  196.098126]  __x64_sys_exit_group+0xf/0x10
[  196.098836]  do_syscall_64+0x3d/0xf0
[  196.099460]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  196.100334] RIP: 0033:0x7f1a8aba5956
[  196.100958] Code: Bad RIP value.
[  196.101293] RSP: 002b:00007fffbdbcad38 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
[  196.101933] RAX: ffffffffffffffda RBX: 00007f1a8ac975c0 RCX: 00007f1a8aba5956
[  196.102535] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
[  196.103137] RBP: 0000000000000000 R08: 00000000000000e7 R09: ffffffffffffff78
[  196.103739] R10: 00007fffbdbcabf8 R11: 0000000000000246 R12: 00007f1a8ac975c0
[  196.104526] R13: 0000000000000001 R14: 00007f1a8aca0288 R15: 0000000000000000
[  196.105777] ---[ end trace 8a7e42f9199e5f93 ]---
[  196.107535] unix: Attempt to release alive unix socket: 000000003b3c1a34

which corresponds to the WARN_ONs:

	WARN_ON(!sk_unhashed(sk));
	WARN_ON(sk->sk_socket);

This doesn't seem to happen if I omit the call to io_uring_register.

> +			kfree_skb(skb);
> +	}
> +#else
> +	int i;
> +
> +	for (i = 0; i < ctx->nr_user_files; i++)
> +		fput(ctx->user_files[i]);
> +#endif
> +}
> +
> +static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
> +{
> +	if (!ctx->user_files)
> +		return -ENXIO;
> +
> +	__io_sqe_files_unregister(ctx);
> +	kfree(ctx->user_files);
> +	ctx->user_files = NULL;
> +	return 0;
> +}
> +
> +#if defined(CONFIG_UNIX)
> +static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
> +{
> +	struct scm_fp_list *fpl;
> +	struct sk_buff *skb;
> +	int i;
> +
> +	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
> +	if (!fpl)
> +		return -ENOMEM;
> +
> +	skb = alloc_skb(0, GFP_KERNEL);
> +	if (!skb) {
> +		kfree(fpl);
> +		return -ENOMEM;
> +	}
> +
> +	skb->sk = ctx->ring_sock->sk;
> +	skb->destructor = unix_destruct_scm;
> +
> +	fpl->user = get_uid(ctx->user);
> +	for (i = 0; i < nr; i++) {
> +		fpl->fp[i] = get_file(ctx->user_files[i + offset]);
> +		unix_inflight(fpl->user, fpl->fp[i]);
> +	}
> +
> +	fpl->max = fpl->count = nr;
> +	UNIXCB(skb).fp = fpl;
> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
> +
> +	for (i = 0; i < nr; i++)
> +		fput(fpl->fp[i]);
> +
> +	return 0;
> +}
> +
> +/*
> + * If UNIX sockets are enabled, fd passing can cause a reference cycle which
> + * causes regular reference counting to break down. We rely on the UNIX
> + * garbage collection to take care of this problem for us.
> + */
> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
> +{
> +	unsigned left, total;
> +	int ret = 0;
> +
> +	total = 0;
> +	left = ctx->nr_user_files;
> +	while (left) {
> +		unsigned this_files = min_t(unsigned, left, SCM_MAX_FD);
> +		int ret;
> +
> +		ret = __io_sqe_files_scm(ctx, this_files, total);
> +		if (ret)
> +			break;
> +		left -= this_files;
> +		total += this_files;
> +	}
> +
> +	return ret;
> +}
> +#else
> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
> +{
> +	return 0;
> +}
> +#endif
> +
> +static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
> +				 unsigned nr_args)
> +{
> +	__s32 __user *fds = (__s32 __user *) arg;
> +	int fd, ret = 0;
> +	unsigned i;
> +
> +	if (ctx->user_files)
> +		return -EBUSY;
> +	if (!nr_args)
> +		return -EINVAL;
> +	if (nr_args > IORING_MAX_FIXED_FILES)
> +		return -EMFILE;
> +
> +	ctx->user_files = kcalloc(nr_args, sizeof(struct file *), GFP_KERNEL);
> +	if (!ctx->user_files)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < nr_args; i++) {
> +		ret = -EFAULT;
> +		if (copy_from_user(&fd, &fds[i], sizeof(fd)))
> +			break;
> +
> +		ctx->user_files[i] = fget(fd);
> +
> +		ret = -EBADF;
> +		if (!ctx->user_files[i])
> +			break;
> +		/*
> +		 * Don't allow io_uring instances to be registered. If UNIX
> +		 * isn't enabled, then this causes a reference cycle and this
> +		 * instance can never get freed. If UNIX is enabled we'll
> +		 * handle it just fine, but there's still no point in allowing
> +		 * a ring fd as it doesn't support regular read/write anyway.
> +		 */
> +		if (ctx->user_files[i]->f_op == &io_uring_fops) {
> +			fput(ctx->user_files[i]);
> +			break;
> +		}
> +		ctx->nr_user_files++;
> +		ret = 0;
> +	}
> +
> +	if (!ret)
> +		ret = io_sqe_files_scm(ctx);
> +	if (ret)
> +		io_sqe_files_unregister(ctx);
> +
> +	return ret;
> +}
> +
>  static int io_sq_offload_start(struct io_ring_ctx *ctx)
>  {
>  	int ret;
> @@ -1560,14 +1754,16 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
>  		destroy_workqueue(ctx->sqo_wq);
>  	if (ctx->sqo_mm)
>  		mmdrop(ctx->sqo_mm);
> +
> +	io_iopoll_reap_events(ctx);
> +	io_sqe_buffer_unregister(ctx);
> +	io_sqe_files_unregister(ctx);
> +
>  #if defined(CONFIG_UNIX)
>  	if (ctx->ring_sock)
>  		sock_release(ctx->ring_sock);
>  #endif
>  
> -	io_iopoll_reap_events(ctx);
> -	io_sqe_buffer_unregister(ctx);
> -
>  	io_mem_free(ctx->sq_ring);
>  	io_mem_free(ctx->sq_sqes);
>  	io_mem_free(ctx->cq_ring);
> @@ -1934,6 +2130,15 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
>  			break;
>  		ret = io_sqe_buffer_unregister(ctx);
>  		break;
> +	case IORING_REGISTER_FILES:
> +		ret = io_sqe_files_register(ctx, arg, nr_args);
> +		break;
> +	case IORING_UNREGISTER_FILES:
> +		ret = -EINVAL;
> +		if (arg || nr_args)
> +			break;
> +		ret = io_sqe_files_unregister(ctx);
> +		break;
>  	default:
>  		ret = -EINVAL;
>  		break;
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index cf28f7a11f12..6257478d55e9 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -16,7 +16,7 @@
>   */
>  struct io_uring_sqe {
>  	__u8	opcode;		/* type of operation for this sqe */
> -	__u8	flags;		/* as of now unused */
> +	__u8	flags;		/* IOSQE_ flags */
>  	__u16	ioprio;		/* ioprio for the request */
>  	__s32	fd;		/* file descriptor to do IO on */
>  	__u64	off;		/* offset into file */
> @@ -33,6 +33,11 @@ struct io_uring_sqe {
>  	};
>  };
>  
> +/*
> + * sqe->flags
> + */
> +#define IOSQE_FIXED_FILE	(1U << 0)	/* use fixed fileset */
> +
>  /*
>   * io_uring_setup() flags
>   */
> @@ -113,5 +118,7 @@ struct io_uring_params {
>   */
>  #define IORING_REGISTER_BUFFERS		0
>  #define IORING_UNREGISTER_BUFFERS	1
> +#define IORING_REGISTER_FILES		2
> +#define IORING_UNREGISTER_FILES		3
>  
>  #endif

  reply index

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-09 21:13 [PATCHSET v14] io_uring IO interface Jens Axboe
2019-02-09 21:13 ` [PATCH 01/19] fs: add an iopoll method to struct file_operations Jens Axboe
2019-02-09 21:13 ` [PATCH 02/19] block: wire up block device iopoll method Jens Axboe
2019-02-09 21:13 ` [PATCH 03/19] block: add bio_set_polled() helper Jens Axboe
2019-02-09 21:13 ` [PATCH 04/19] iomap: wire up the iopoll method Jens Axboe
2019-02-09 21:13 ` [PATCH 05/19] Add io_uring IO interface Jens Axboe
2019-02-10 12:03   ` Thomas Gleixner
2019-02-10 14:19     ` Jens Axboe
2019-02-09 21:13 ` [PATCH 06/19] io_uring: add fsync support Jens Axboe
2019-02-09 21:13 ` [PATCH 07/19] io_uring: support for IO polling Jens Axboe
2019-02-09 21:13 ` [PATCH 08/19] fs: add fget_many() and fput_many() Jens Axboe
2019-02-09 21:13 ` [PATCH 09/19] io_uring: use fget/fput_many() for file references Jens Axboe
2019-02-09 21:13 ` [PATCH 10/19] io_uring: batch io_kiocb allocation Jens Axboe
2019-02-09 21:13 ` [PATCH 11/19] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-02-09 21:13 ` [PATCH 12/19] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-02-09 21:13 ` [PATCH 13/19] net: split out functions related to registering inflight socket files Jens Axboe
2019-02-09 21:13 ` [PATCH 14/19] io_uring: add file set registration Jens Axboe
2019-02-09 23:52   ` Matt Mullins [this message]
2019-02-10  0:47     ` Jens Axboe
     [not found]       ` <60e4c6a489549daad1fb2c5e8eee5496c668d79a.camel@fb.com>
2019-02-10  2:34         ` Jens Axboe
2019-02-10  2:57           ` Jens Axboe
2019-02-10 19:55             ` Matt Mullins
2019-02-09 21:13 ` [PATCH 15/19] io_uring: add submission polling Jens Axboe
2019-02-09 21:13 ` [PATCH 16/19] io_uring: add io_kiocb ref count Jens Axboe
2019-02-10  9:19   ` Hannes Reinecke
2019-02-09 21:13 ` [PATCH 17/19] io_uring: add support for IORING_OP_POLL Jens Axboe
2019-02-10  9:28   ` Hannes Reinecke
2019-02-09 21:13 ` [PATCH 18/19] io_uring: allow workqueue item to handle multiple buffered requests Jens Axboe
2019-02-10  9:31   ` Hannes Reinecke
2019-02-09 21:13 ` [PATCH 19/19] io_uring: add io_uring_event cache hit information Jens Axboe
2019-02-10  9:36   ` Hannes Reinecke
2019-02-10 13:39     ` Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2019-02-11 19:00 [PATCHSET v15] io_uring IO interface Jens Axboe
2019-02-11 19:00 ` [PATCH 14/19] io_uring: add file set registration Jens Axboe
2019-02-19 16:12   ` Jann Horn
2019-02-22 22:29     ` Jens Axboe
2019-02-08 17:34 [PATCHSET v13] io_uring IO interface Jens Axboe
2019-02-08 17:34 ` [PATCH 14/19] io_uring: add file set registration Jens Axboe
2019-02-08 20:26   ` Jann Horn
2019-02-09  0:16     ` Jens Axboe
2019-02-09  9:50   ` Hannes Reinecke

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