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rw.c
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// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/blk-mq.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/fsnotify.h>
#include <linux/poll.h>
#include <linux/nospec.h>
#include <linux/compat.h>
#include <linux/io_uring/cmd.h>
#include <uapi/linux/io_uring.h>
#include "io_uring.h"
#include "opdef.h"
#include "kbuf.h"
#include "rsrc.h"
#include "rw.h"
struct io_rw {
/* NOTE: kiocb has the file as the first member, so don't do it here */
struct kiocb kiocb;
u64 addr;
u32 len;
rwf_t flags;
};
static inline bool io_file_supports_nowait(struct io_kiocb *req)
{
return req->flags & REQ_F_SUPPORT_NOWAIT;
}
#ifdef CONFIG_COMPAT
static int io_iov_compat_buffer_select_prep(struct io_rw *rw)
{
struct compat_iovec __user *uiov;
compat_ssize_t clen;
uiov = u64_to_user_ptr(rw->addr);
if (!access_ok(uiov, sizeof(*uiov)))
return -EFAULT;
if (__get_user(clen, &uiov->iov_len))
return -EFAULT;
if (clen < 0)
return -EINVAL;
rw->len = clen;
return 0;
}
#endif
static int io_iov_buffer_select_prep(struct io_kiocb *req)
{
struct iovec __user *uiov;
struct iovec iov;
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
if (rw->len != 1)
return -EINVAL;
#ifdef CONFIG_COMPAT
if (req->ctx->compat)
return io_iov_compat_buffer_select_prep(rw);
#endif
uiov = u64_to_user_ptr(rw->addr);
if (copy_from_user(&iov, uiov, sizeof(*uiov)))
return -EFAULT;
rw->len = iov.iov_len;
return 0;
}
int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
unsigned ioprio;
int ret;
rw->kiocb.ki_pos = READ_ONCE(sqe->off);
/* used for fixed read/write too - just read unconditionally */
req->buf_index = READ_ONCE(sqe->buf_index);
ioprio = READ_ONCE(sqe->ioprio);
if (ioprio) {
ret = ioprio_check_cap(ioprio);
if (ret)
return ret;
rw->kiocb.ki_ioprio = ioprio;
} else {
rw->kiocb.ki_ioprio = get_current_ioprio();
}
rw->kiocb.dio_complete = NULL;
rw->addr = READ_ONCE(sqe->addr);
rw->len = READ_ONCE(sqe->len);
rw->flags = READ_ONCE(sqe->rw_flags);
return 0;
}
int io_prep_rwv(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
int ret;
ret = io_prep_rw(req, sqe);
if (unlikely(ret))
return ret;
/*
* Have to do this validation here, as this is in io_read() rw->len
* might have chanaged due to buffer selection
*/
if (req->flags & REQ_F_BUFFER_SELECT)
return io_iov_buffer_select_prep(req);
return 0;
}
int io_prep_rw_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_ring_ctx *ctx = req->ctx;
u16 index;
int ret;
ret = io_prep_rw(req, sqe);
if (unlikely(ret))
return ret;
if (unlikely(req->buf_index >= ctx->nr_user_bufs))
return -EFAULT;
index = array_index_nospec(req->buf_index, ctx->nr_user_bufs);
req->imu = ctx->user_bufs[index];
io_req_set_rsrc_node(req, ctx, 0);
return 0;
}
/*
* Multishot read is prepared just like a normal read/write request, only
* difference is that we set the MULTISHOT flag.
*/
int io_read_mshot_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
int ret;
/* must be used with provided buffers */
if (!(req->flags & REQ_F_BUFFER_SELECT))
return -EINVAL;
ret = io_prep_rw(req, sqe);
if (unlikely(ret))
return ret;
if (rw->addr || rw->len)
return -EINVAL;
req->flags |= REQ_F_APOLL_MULTISHOT;
return 0;
}
void io_readv_writev_cleanup(struct io_kiocb *req)
{
struct io_async_rw *io = req->async_data;
kfree(io->free_iovec);
}
static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
if (rw->kiocb.ki_pos != -1)
return &rw->kiocb.ki_pos;
if (!(req->file->f_mode & FMODE_STREAM)) {
req->flags |= REQ_F_CUR_POS;
rw->kiocb.ki_pos = req->file->f_pos;
return &rw->kiocb.ki_pos;
}
rw->kiocb.ki_pos = 0;
return NULL;
}
static void io_req_task_queue_reissue(struct io_kiocb *req)
{
req->io_task_work.func = io_queue_iowq;
io_req_task_work_add(req);
}
#ifdef CONFIG_BLOCK
static bool io_resubmit_prep(struct io_kiocb *req)
{
struct io_async_rw *io = req->async_data;
if (!req_has_async_data(req))
return !io_req_prep_async(req);
iov_iter_restore(&io->s.iter, &io->s.iter_state);
return true;
}
static bool io_rw_should_reissue(struct io_kiocb *req)
{
umode_t mode = file_inode(req->file)->i_mode;
struct io_ring_ctx *ctx = req->ctx;
if (!S_ISBLK(mode) && !S_ISREG(mode))
return false;
if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() &&
!(ctx->flags & IORING_SETUP_IOPOLL)))
return false;
/*
* If ref is dying, we might be running poll reap from the exit work.
* Don't attempt to reissue from that path, just let it fail with
* -EAGAIN.
*/
if (percpu_ref_is_dying(&ctx->refs))
return false;
/*
* Play it safe and assume not safe to re-import and reissue if we're
* not in the original thread group (or in task context).
*/
if (!same_thread_group(req->task, current) || !in_task())
return false;
return true;
}
#else
static bool io_resubmit_prep(struct io_kiocb *req)
{
return false;
}
static bool io_rw_should_reissue(struct io_kiocb *req)
{
return false;
}
#endif
static void io_req_end_write(struct io_kiocb *req)
{
if (req->flags & REQ_F_ISREG) {
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
kiocb_end_write(&rw->kiocb);
}
}
/*
* Trigger the notifications after having done some IO, and finish the write
* accounting, if any.
*/
static void io_req_io_end(struct io_kiocb *req)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
if (rw->kiocb.ki_flags & IOCB_WRITE) {
io_req_end_write(req);
fsnotify_modify(req->file);
} else {
fsnotify_access(req->file);
}
}
static bool __io_complete_rw_common(struct io_kiocb *req, long res)
{
if (unlikely(res != req->cqe.res)) {
if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
io_rw_should_reissue(req)) {
/*
* Reissue will start accounting again, finish the
* current cycle.
*/
io_req_io_end(req);
req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO;
return true;
}
req_set_fail(req);
req->cqe.res = res;
}
return false;
}
static inline int io_fixup_rw_res(struct io_kiocb *req, long res)
{
struct io_async_rw *io = req->async_data;
/* add previously done IO, if any */
if (req_has_async_data(req) && io->bytes_done > 0) {
if (res < 0)
res = io->bytes_done;
else
res += io->bytes_done;
}
return res;
}
void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
struct kiocb *kiocb = &rw->kiocb;
if ((kiocb->ki_flags & IOCB_DIO_CALLER_COMP) && kiocb->dio_complete) {
long res = kiocb->dio_complete(rw->kiocb.private);
io_req_set_res(req, io_fixup_rw_res(req, res), 0);
}
io_req_io_end(req);
if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) {
unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED;
req->cqe.flags |= io_put_kbuf(req, issue_flags);
}
io_req_task_complete(req, ts);
}
static void io_complete_rw(struct kiocb *kiocb, long res)
{
struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
struct io_kiocb *req = cmd_to_io_kiocb(rw);
if (!kiocb->dio_complete || !(kiocb->ki_flags & IOCB_DIO_CALLER_COMP)) {
if (__io_complete_rw_common(req, res))
return;
io_req_set_res(req, io_fixup_rw_res(req, res), 0);
}
req->io_task_work.func = io_req_rw_complete;
__io_req_task_work_add(req, IOU_F_TWQ_LAZY_WAKE);
}
static void io_complete_rw_iopoll(struct kiocb *kiocb, long res)
{
struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
struct io_kiocb *req = cmd_to_io_kiocb(rw);
if (kiocb->ki_flags & IOCB_WRITE)
io_req_end_write(req);
if (unlikely(res != req->cqe.res)) {
if (res == -EAGAIN && io_rw_should_reissue(req)) {
req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO;
return;
}
req->cqe.res = res;
}
/* order with io_iopoll_complete() checking ->iopoll_completed */
smp_store_release(&req->iopoll_completed, 1);
}
static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
{
/* IO was queued async, completion will happen later */
if (ret == -EIOCBQUEUED)
return;
/* transform internal restart error codes */
if (unlikely(ret < 0)) {
switch (ret) {
case -ERESTARTSYS:
case -ERESTARTNOINTR:
case -ERESTARTNOHAND:
case -ERESTART_RESTARTBLOCK:
/*
* We can't just restart the syscall, since previously
* submitted sqes may already be in progress. Just fail
* this IO with EINTR.
*/
ret = -EINTR;
break;
}
}
INDIRECT_CALL_2(kiocb->ki_complete, io_complete_rw_iopoll,
io_complete_rw, kiocb, ret);
}
static int kiocb_done(struct io_kiocb *req, ssize_t ret,
unsigned int issue_flags)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
unsigned final_ret = io_fixup_rw_res(req, ret);
if (ret >= 0 && req->flags & REQ_F_CUR_POS)
req->file->f_pos = rw->kiocb.ki_pos;
if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) {
if (!__io_complete_rw_common(req, ret)) {
/*
* Safe to call io_end from here as we're inline
* from the submission path.
*/
io_req_io_end(req);
io_req_set_res(req, final_ret,
io_put_kbuf(req, issue_flags));
return IOU_OK;
}
} else {
io_rw_done(&rw->kiocb, ret);
}
if (req->flags & REQ_F_REISSUE) {
req->flags &= ~REQ_F_REISSUE;
if (io_resubmit_prep(req))
io_req_task_queue_reissue(req);
else
io_req_task_queue_fail(req, final_ret);
}
return IOU_ISSUE_SKIP_COMPLETE;
}
static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req,
struct io_rw_state *s,
unsigned int issue_flags)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
struct iov_iter *iter = &s->iter;
u8 opcode = req->opcode;
struct iovec *iovec;
void __user *buf;
size_t sqe_len;
ssize_t ret;
if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
ret = io_import_fixed(ddir, iter, req->imu, rw->addr, rw->len);
if (ret)
return ERR_PTR(ret);
return NULL;
}
buf = u64_to_user_ptr(rw->addr);
sqe_len = rw->len;
if (!io_issue_defs[opcode].vectored || req->flags & REQ_F_BUFFER_SELECT) {
if (io_do_buffer_select(req)) {
buf = io_buffer_select(req, &sqe_len, issue_flags);
if (!buf)
return ERR_PTR(-ENOBUFS);
rw->addr = (unsigned long) buf;
rw->len = sqe_len;
}
ret = import_ubuf(ddir, buf, sqe_len, iter);
if (ret)
return ERR_PTR(ret);
return NULL;
}
iovec = s->fast_iov;
ret = __import_iovec(ddir, buf, sqe_len, UIO_FASTIOV, &iovec, iter,
req->ctx->compat);
if (unlikely(ret < 0))
return ERR_PTR(ret);
return iovec;
}
static inline int io_import_iovec(int rw, struct io_kiocb *req,
struct iovec **iovec, struct io_rw_state *s,
unsigned int issue_flags)
{
*iovec = __io_import_iovec(rw, req, s, issue_flags);
if (IS_ERR(*iovec))
return PTR_ERR(*iovec);
iov_iter_save_state(&s->iter, &s->iter_state);
return 0;
}
static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
{
return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos;
}
/*
* For files that don't have ->read_iter() and ->write_iter(), handle them
* by looping over ->read() or ->write() manually.
*/
static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
{
struct kiocb *kiocb = &rw->kiocb;
struct file *file = kiocb->ki_filp;
ssize_t ret = 0;
loff_t *ppos;
/*
* Don't support polled IO through this interface, and we can't
* support non-blocking either. For the latter, this just causes
* the kiocb to be handled from an async context.
*/
if (kiocb->ki_flags & IOCB_HIPRI)
return -EOPNOTSUPP;
if ((kiocb->ki_flags & IOCB_NOWAIT) &&
!(kiocb->ki_filp->f_flags & O_NONBLOCK))
return -EAGAIN;
ppos = io_kiocb_ppos(kiocb);
while (iov_iter_count(iter)) {
void __user *addr;
size_t len;
ssize_t nr;
if (iter_is_ubuf(iter)) {
addr = iter->ubuf + iter->iov_offset;
len = iov_iter_count(iter);
} else if (!iov_iter_is_bvec(iter)) {
addr = iter_iov_addr(iter);
len = iter_iov_len(iter);
} else {
addr = u64_to_user_ptr(rw->addr);
len = rw->len;
}
if (ddir == READ)
nr = file->f_op->read(file, addr, len, ppos);
else
nr = file->f_op->write(file, addr, len, ppos);
if (nr < 0) {
if (!ret)
ret = nr;
break;
}
ret += nr;
if (!iov_iter_is_bvec(iter)) {
iov_iter_advance(iter, nr);
} else {
rw->addr += nr;
rw->len -= nr;
if (!rw->len)
break;
}
if (nr != len)
break;
}
return ret;
}
static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
const struct iovec *fast_iov, struct iov_iter *iter)
{
struct io_async_rw *io = req->async_data;
memcpy(&io->s.iter, iter, sizeof(*iter));
io->free_iovec = iovec;
io->bytes_done = 0;
/* can only be fixed buffers, no need to do anything */
if (iov_iter_is_bvec(iter) || iter_is_ubuf(iter))
return;
if (!iovec) {
unsigned iov_off = 0;
io->s.iter.__iov = io->s.fast_iov;
if (iter->__iov != fast_iov) {
iov_off = iter_iov(iter) - fast_iov;
io->s.iter.__iov += iov_off;
}
if (io->s.fast_iov != fast_iov)
memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off,
sizeof(struct iovec) * iter->nr_segs);
} else {
req->flags |= REQ_F_NEED_CLEANUP;
}
}
static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
struct io_rw_state *s, bool force)
{
if (!force && !io_cold_defs[req->opcode].prep_async)
return 0;
/* opcode type doesn't need async data */
if (!io_cold_defs[req->opcode].async_size)
return 0;
if (!req_has_async_data(req)) {
struct io_async_rw *iorw;
if (io_alloc_async_data(req)) {
kfree(iovec);
return -ENOMEM;
}
io_req_map_rw(req, iovec, s->fast_iov, &s->iter);
iorw = req->async_data;
/* we've copied and mapped the iter, ensure state is saved */
iov_iter_save_state(&iorw->s.iter, &iorw->s.iter_state);
}
return 0;
}
static inline int io_rw_prep_async(struct io_kiocb *req, int rw)
{
struct io_async_rw *iorw = req->async_data;
struct iovec *iov;
int ret;
iorw->bytes_done = 0;
iorw->free_iovec = NULL;
/* submission path, ->uring_lock should already be taken */
ret = io_import_iovec(rw, req, &iov, &iorw->s, 0);
if (unlikely(ret < 0))
return ret;
if (iov) {
iorw->free_iovec = iov;
req->flags |= REQ_F_NEED_CLEANUP;
}
return 0;
}
int io_readv_prep_async(struct io_kiocb *req)
{
return io_rw_prep_async(req, ITER_DEST);
}
int io_writev_prep_async(struct io_kiocb *req)
{
return io_rw_prep_async(req, ITER_SOURCE);
}
/*
* This is our waitqueue callback handler, registered through __folio_lock_async()
* when we initially tried to do the IO with the iocb armed our waitqueue.
* This gets called when the page is unlocked, and we generally expect that to
* happen when the page IO is completed and the page is now uptodate. This will
* queue a task_work based retry of the operation, attempting to copy the data
* again. If the latter fails because the page was NOT uptodate, then we will
* do a thread based blocking retry of the operation. That's the unexpected
* slow path.
*/
static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode,
int sync, void *arg)
{
struct wait_page_queue *wpq;
struct io_kiocb *req = wait->private;
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
struct wait_page_key *key = arg;
wpq = container_of(wait, struct wait_page_queue, wait);
if (!wake_page_match(wpq, key))
return 0;
rw->kiocb.ki_flags &= ~IOCB_WAITQ;
list_del_init(&wait->entry);
io_req_task_queue(req);
return 1;
}
/*
* This controls whether a given IO request should be armed for async page
* based retry. If we return false here, the request is handed to the async
* worker threads for retry. If we're doing buffered reads on a regular file,
* we prepare a private wait_page_queue entry and retry the operation. This
* will either succeed because the page is now uptodate and unlocked, or it
* will register a callback when the page is unlocked at IO completion. Through
* that callback, io_uring uses task_work to setup a retry of the operation.
* That retry will attempt the buffered read again. The retry will generally
* succeed, or in rare cases where it fails, we then fall back to using the
* async worker threads for a blocking retry.
*/
static bool io_rw_should_retry(struct io_kiocb *req)
{
struct io_async_rw *io = req->async_data;
struct wait_page_queue *wait = &io->wpq;
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
struct kiocb *kiocb = &rw->kiocb;
/* never retry for NOWAIT, we just complete with -EAGAIN */
if (req->flags & REQ_F_NOWAIT)
return false;
/* Only for buffered IO */
if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI))
return false;
/*
* just use poll if we can, and don't attempt if the fs doesn't
* support callback based unlocks
*/
if (file_can_poll(req->file) || !(req->file->f_mode & FMODE_BUF_RASYNC))
return false;
wait->wait.func = io_async_buf_func;
wait->wait.private = req;
wait->wait.flags = 0;
INIT_LIST_HEAD(&wait->wait.entry);
kiocb->ki_flags |= IOCB_WAITQ;
kiocb->ki_flags &= ~IOCB_NOWAIT;
kiocb->ki_waitq = wait;
return true;
}
static inline int io_iter_do_read(struct io_rw *rw, struct iov_iter *iter)
{
struct file *file = rw->kiocb.ki_filp;
if (likely(file->f_op->read_iter))
return call_read_iter(file, &rw->kiocb, iter);
else if (file->f_op->read)
return loop_rw_iter(READ, rw, iter);
else
return -EINVAL;
}
static bool need_complete_io(struct io_kiocb *req)
{
return req->flags & REQ_F_ISREG ||
S_ISBLK(file_inode(req->file)->i_mode);
}
static int io_rw_init_file(struct io_kiocb *req, fmode_t mode)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
struct kiocb *kiocb = &rw->kiocb;
struct io_ring_ctx *ctx = req->ctx;
struct file *file = req->file;
int ret;
if (unlikely(!file || !(file->f_mode & mode)))
return -EBADF;
if (!(req->flags & REQ_F_FIXED_FILE))
req->flags |= io_file_get_flags(file);
kiocb->ki_flags = file->f_iocb_flags;
ret = kiocb_set_rw_flags(kiocb, rw->flags);
if (unlikely(ret))
return ret;
kiocb->ki_flags |= IOCB_ALLOC_CACHE;
/*
* If the file is marked O_NONBLOCK, still allow retry for it if it
* supports async. Otherwise it's impossible to use O_NONBLOCK files
* reliably. If not, or it IOCB_NOWAIT is set, don't retry.
*/
if ((kiocb->ki_flags & IOCB_NOWAIT) ||
((file->f_flags & O_NONBLOCK) && !io_file_supports_nowait(req)))
req->flags |= REQ_F_NOWAIT;
if (ctx->flags & IORING_SETUP_IOPOLL) {
if (!(kiocb->ki_flags & IOCB_DIRECT) || !file->f_op->iopoll)
return -EOPNOTSUPP;
kiocb->private = NULL;
kiocb->ki_flags |= IOCB_HIPRI;
kiocb->ki_complete = io_complete_rw_iopoll;
req->iopoll_completed = 0;
} else {
if (kiocb->ki_flags & IOCB_HIPRI)
return -EINVAL;
kiocb->ki_complete = io_complete_rw;
}
return 0;
}
static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
struct io_rw_state __s, *s = &__s;
struct iovec *iovec;
struct kiocb *kiocb = &rw->kiocb;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
struct io_async_rw *io;
ssize_t ret, ret2;
loff_t *ppos;
if (!req_has_async_data(req)) {
ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
if (unlikely(ret < 0))
return ret;
} else {
io = req->async_data;
s = &io->s;
/*
* Safe and required to re-import if we're using provided
* buffers, as we dropped the selected one before retry.
*/
if (io_do_buffer_select(req)) {
ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
if (unlikely(ret < 0))
return ret;
}
/*
* We come here from an earlier attempt, restore our state to
* match in case it doesn't. It's cheap enough that we don't
* need to make this conditional.
*/
iov_iter_restore(&s->iter, &s->iter_state);
iovec = NULL;
}
ret = io_rw_init_file(req, FMODE_READ);
if (unlikely(ret)) {
kfree(iovec);
return ret;
}
req->cqe.res = iov_iter_count(&s->iter);
if (force_nonblock) {
/* If the file doesn't support async, just async punt */
if (unlikely(!io_file_supports_nowait(req))) {
ret = io_setup_async_rw(req, iovec, s, true);
return ret ?: -EAGAIN;
}
kiocb->ki_flags |= IOCB_NOWAIT;
} else {
/* Ensure we clear previously set non-block flag */
kiocb->ki_flags &= ~IOCB_NOWAIT;
}
ppos = io_kiocb_update_pos(req);
ret = rw_verify_area(READ, req->file, ppos, req->cqe.res);
if (unlikely(ret)) {
kfree(iovec);
return ret;
}
ret = io_iter_do_read(rw, &s->iter);
if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
req->flags &= ~REQ_F_REISSUE;
/*
* If we can poll, just do that. For a vectored read, we'll
* need to copy state first.
*/
if (file_can_poll(req->file) && !io_issue_defs[req->opcode].vectored)
return -EAGAIN;
/* IOPOLL retry should happen for io-wq threads */
if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
goto done;
/* no retry on NONBLOCK nor RWF_NOWAIT */
if (req->flags & REQ_F_NOWAIT)
goto done;
ret = 0;
} else if (ret == -EIOCBQUEUED) {
if (iovec)
kfree(iovec);
return IOU_ISSUE_SKIP_COMPLETE;
} else if (ret == req->cqe.res || ret <= 0 || !force_nonblock ||
(req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) {
/* read all, failed, already did sync or don't want to retry */
goto done;
}
/*
* Don't depend on the iter state matching what was consumed, or being
* untouched in case of error. Restore it and we'll advance it
* manually if we need to.
*/
iov_iter_restore(&s->iter, &s->iter_state);
ret2 = io_setup_async_rw(req, iovec, s, true);
iovec = NULL;
if (ret2) {
ret = ret > 0 ? ret : ret2;
goto done;
}
io = req->async_data;
s = &io->s;
/*
* Now use our persistent iterator and state, if we aren't already.
* We've restored and mapped the iter to match.
*/
do {
/*
* We end up here because of a partial read, either from
* above or inside this loop. Advance the iter by the bytes
* that were consumed.
*/
iov_iter_advance(&s->iter, ret);
if (!iov_iter_count(&s->iter))
break;
io->bytes_done += ret;
iov_iter_save_state(&s->iter, &s->iter_state);
/* if we can retry, do so with the callbacks armed */
if (!io_rw_should_retry(req)) {
kiocb->ki_flags &= ~IOCB_WAITQ;
return -EAGAIN;
}
req->cqe.res = iov_iter_count(&s->iter);
/*
* Now retry read with the IOCB_WAITQ parts set in the iocb. If
* we get -EIOCBQUEUED, then we'll get a notification when the
* desired page gets unlocked. We can also get a partial read
* here, and if we do, then just retry at the new offset.
*/
ret = io_iter_do_read(rw, &s->iter);
if (ret == -EIOCBQUEUED)
return IOU_ISSUE_SKIP_COMPLETE;
/* we got some bytes, but not all. retry. */
kiocb->ki_flags &= ~IOCB_WAITQ;
iov_iter_restore(&s->iter, &s->iter_state);
} while (ret > 0);
done:
/* it's faster to check here then delegate to kfree */
if (iovec)
kfree(iovec);
return ret;
}
int io_read(struct io_kiocb *req, unsigned int issue_flags)
{
int ret;
ret = __io_read(req, issue_flags);
if (ret >= 0)
return kiocb_done(req, ret, issue_flags);
return ret;
}
int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
unsigned int cflags = 0;
int ret;
/*
* Multishot MUST be used on a pollable file
*/
if (!file_can_poll(req->file))
return -EBADFD;
ret = __io_read(req, issue_flags);
/*
* If we get -EAGAIN, recycle our buffer and just let normal poll
* handling arm it.
*/
if (ret == -EAGAIN) {
/*
* Reset rw->len to 0 again to avoid clamping future mshot
* reads, in case the buffer size varies.
*/
if (io_kbuf_recycle(req, issue_flags))
rw->len = 0;
return -EAGAIN;
}
/*
* Any successful return value will keep the multishot read armed.
*/
if (ret > 0) {
/*
* Put our buffer and post a CQE. If we fail to post a CQE, then
* jump to the termination path. This request is then done.
*/
cflags = io_put_kbuf(req, issue_flags);
rw->len = 0; /* similarly to above, reset len to 0 */
if (io_fill_cqe_req_aux(req,
issue_flags & IO_URING_F_COMPLETE_DEFER,
ret, cflags | IORING_CQE_F_MORE)) {
if (issue_flags & IO_URING_F_MULTISHOT)
return IOU_ISSUE_SKIP_COMPLETE;
return -EAGAIN;
}
}
/*
* Either an error, or we've hit overflow posting the CQE. For any
* multishot request, hitting overflow will terminate it.
*/
io_req_set_res(req, ret, cflags);
if (issue_flags & IO_URING_F_MULTISHOT)
return IOU_STOP_MULTISHOT;
return IOU_OK;
}
int io_write(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
struct io_rw_state __s, *s = &__s;
struct iovec *iovec;
struct kiocb *kiocb = &rw->kiocb;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
ssize_t ret, ret2;
loff_t *ppos;
if (!req_has_async_data(req)) {
ret = io_import_iovec(ITER_SOURCE, req, &iovec, s, issue_flags);
if (unlikely(ret < 0))
return ret;
} else {
struct io_async_rw *io = req->async_data;
s = &io->s;
iov_iter_restore(&s->iter, &s->iter_state);
iovec = NULL;