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io_uring: add lookup table for various opcode needs
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We currently have various switch statements that check if an opcode needs
a file, mm, etc. These are hard to keep in sync as opcodes are added. Add
a struct io_op_def that holds all of this information, so we have just
one spot to update when opcodes are added.

This also enables us to NOT allocate req->io if a deferred command
doesn't need it, and corrects some mistakes we had in terms of what
commands need mm context.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Jens Axboe committed Jan 21, 2020
1 parent add7b6b commit d365634
Showing 1 changed file with 155 additions and 53 deletions.
208 changes: 155 additions & 53 deletions fs/io_uring.c
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Original file line number Diff line number Diff line change
Expand Up @@ -516,6 +516,135 @@ struct io_submit_state {
unsigned int ios_left;
};

struct io_op_def {
/* needs req->io allocated for deferral/async */
unsigned async_ctx : 1;
/* needs current->mm setup, does mm access */
unsigned needs_mm : 1;
/* needs req->file assigned */
unsigned needs_file : 1;
/* needs req->file assigned IFF fd is >= 0 */
unsigned fd_non_neg : 1;
/* hash wq insertion if file is a regular file */
unsigned hash_reg_file : 1;
/* unbound wq insertion if file is a non-regular file */
unsigned unbound_nonreg_file : 1;
};

static const struct io_op_def io_op_defs[] = {
{
/* IORING_OP_NOP */
},
{
/* IORING_OP_READV */
.async_ctx = 1,
.needs_mm = 1,
.needs_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_WRITEV */
.async_ctx = 1,
.needs_mm = 1,
.needs_file = 1,
.hash_reg_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_FSYNC */
.needs_file = 1,
},
{
/* IORING_OP_READ_FIXED */
.needs_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_WRITE_FIXED */
.needs_file = 1,
.hash_reg_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_POLL_ADD */
.needs_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_POLL_REMOVE */
},
{
/* IORING_OP_SYNC_FILE_RANGE */
.needs_file = 1,
},
{
/* IORING_OP_SENDMSG */
.async_ctx = 1,
.needs_mm = 1,
.needs_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_RECVMSG */
.async_ctx = 1,
.needs_mm = 1,
.needs_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_TIMEOUT */
.async_ctx = 1,
.needs_mm = 1,
},
{
/* IORING_OP_TIMEOUT_REMOVE */
},
{
/* IORING_OP_ACCEPT */
.needs_mm = 1,
.needs_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_ASYNC_CANCEL */
},
{
/* IORING_OP_LINK_TIMEOUT */
.async_ctx = 1,
.needs_mm = 1,
},
{
/* IORING_OP_CONNECT */
.async_ctx = 1,
.needs_mm = 1,
.needs_file = 1,
.unbound_nonreg_file = 1,
},
{
/* IORING_OP_FALLOCATE */
.needs_file = 1,
},
{
/* IORING_OP_OPENAT */
.needs_file = 1,
.fd_non_neg = 1,
},
{
/* IORING_OP_CLOSE */
.needs_file = 1,
},
{
/* IORING_OP_FILES_UPDATE */
.needs_mm = 1,
},
{
/* IORING_OP_STATX */
.needs_mm = 1,
.needs_file = 1,
.fd_non_neg = 1,
},
};

static void io_wq_submit_work(struct io_wq_work **workptr);
static void io_cqring_fill_event(struct io_kiocb *req, long res);
static void io_put_req(struct io_kiocb *req);
Expand Down Expand Up @@ -671,41 +800,20 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx)
}
}

static inline bool io_req_needs_user(struct io_kiocb *req)
{
return !(req->opcode == IORING_OP_READ_FIXED ||
req->opcode == IORING_OP_WRITE_FIXED);
}

static inline bool io_prep_async_work(struct io_kiocb *req,
struct io_kiocb **link)
{
const struct io_op_def *def = &io_op_defs[req->opcode];
bool do_hashed = false;

switch (req->opcode) {
case IORING_OP_WRITEV:
case IORING_OP_WRITE_FIXED:
/* only regular files should be hashed for writes */
if (req->flags & REQ_F_ISREG)
if (req->flags & REQ_F_ISREG) {
if (def->hash_reg_file)
do_hashed = true;
/* fall-through */
case IORING_OP_READV:
case IORING_OP_READ_FIXED:
case IORING_OP_SENDMSG:
case IORING_OP_RECVMSG:
case IORING_OP_ACCEPT:
case IORING_OP_POLL_ADD:
case IORING_OP_CONNECT:
/*
* We know REQ_F_ISREG is not set on some of these
* opcodes, but this enables us to keep the check in
* just one place.
*/
if (!(req->flags & REQ_F_ISREG))
} else {
if (def->unbound_nonreg_file)
req->work.flags |= IO_WQ_WORK_UNBOUND;
break;
}
if (io_req_needs_user(req))
if (def->needs_mm)
req->work.flags |= IO_WQ_WORK_NEEDS_USER;

*link = io_prep_linked_timeout(req);
Expand Down Expand Up @@ -1826,6 +1934,8 @@ static void io_req_map_rw(struct io_kiocb *req, ssize_t io_size,

static int io_alloc_async_ctx(struct io_kiocb *req)
{
if (!io_op_defs[req->opcode].async_ctx)
return 0;
req->io = kmalloc(sizeof(*req->io), GFP_KERNEL);
return req->io == NULL;
}
Expand Down Expand Up @@ -3765,29 +3875,13 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
io_wq_assign_next(workptr, nxt);
}

static bool io_req_op_valid(int op)
{
return op >= IORING_OP_NOP && op < IORING_OP_LAST;
}

static int io_req_needs_file(struct io_kiocb *req, int fd)
{
switch (req->opcode) {
case IORING_OP_NOP:
case IORING_OP_POLL_REMOVE:
case IORING_OP_TIMEOUT:
case IORING_OP_TIMEOUT_REMOVE:
case IORING_OP_ASYNC_CANCEL:
case IORING_OP_LINK_TIMEOUT:
if (!io_op_defs[req->opcode].needs_file)
return 0;
case IORING_OP_OPENAT:
case IORING_OP_STATX:
return fd != -1;
default:
if (io_req_op_valid(req->opcode))
return 1;
return -EINVAL;
}
if (fd == -1 && io_op_defs[req->opcode].fd_non_neg)
return 0;
return 1;
}

static inline struct file *io_file_from_index(struct io_ring_ctx *ctx,
Expand All @@ -3804,17 +3898,16 @@ static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,
{
struct io_ring_ctx *ctx = req->ctx;
unsigned flags;
int fd, ret;
int fd;

flags = READ_ONCE(sqe->flags);
fd = READ_ONCE(sqe->fd);

if (flags & IOSQE_IO_DRAIN)
req->flags |= REQ_F_IO_DRAIN;

ret = io_req_needs_file(req, fd);
if (ret <= 0)
return ret;
if (!io_req_needs_file(req, fd))
return 0;

if (flags & IOSQE_FIXED_FILE) {
if (unlikely(!ctx->file_data ||
Expand Down Expand Up @@ -4240,15 +4333,23 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
break;
}

if (io_req_needs_user(req) && !*mm) {
/* will complete beyond this point, count as submitted */
submitted++;

if (unlikely(req->opcode >= IORING_OP_LAST)) {
io_cqring_add_event(req, -EINVAL);
io_double_put_req(req);
break;
}

if (io_op_defs[req->opcode].needs_mm && !*mm) {
mm_fault = mm_fault || !mmget_not_zero(ctx->sqo_mm);
if (!mm_fault) {
use_mm(ctx->sqo_mm);
*mm = ctx->sqo_mm;
}
}

submitted++;
req->ring_file = ring_file;
req->ring_fd = ring_fd;
req->has_user = *mm != NULL;
Expand Down Expand Up @@ -6104,6 +6205,7 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,

static int __init io_uring_init(void)
{
BUILD_BUG_ON(ARRAY_SIZE(io_op_defs) != IORING_OP_LAST);
req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
return 0;
};
Expand Down

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