linux/io_uring/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 <linux/indirect_call_wrapper.h>
#include <uapi/linux/io_uring.h>
#include "io_uring.h"
#include "opdef.h"
#include "kbuf.h"
#include "rsrc.h"
io_uring/rw: ensure poll based multishot read retries appropriately io_read_mshot() always relies on poll triggering retries, and this works fine as long as we do a retry per size of the buffer being read. The buffer size is given by the size of the buffer(s) in the given buffer group ID. But if we're reading less than what is available, then we don't always get to read everything that is available. For example, if the buffers available are 32 bytes and we have 64 bytes to read, then we'll correctly read the first 32 bytes and then wait for another poll trigger before we attempt the next read. This next poll trigger may never happen, in which case we just sit forever and never make progress, or it may trigger at some point in the future, and now we're just delivering the available data much later than we should have. io_read_mshot() could do retries itself, but that is wasteful as we'll be going through all of __io_read() again, and most likely in vain. Rather than do that, bump our poll reference count and have io_poll_check_events() do one more loop and check with vfs_poll() if we have more data to read. If we do, io_read_mshot() will get invoked again directly and we'll read the next chunk. io_poll_multishot_retry() must only get called from inside io_poll_issue(), which is our multishot retry handler, as we know we already "own" the request at this point. Cc: stable@vger.kernel.org Link: https://github.com/axboe/liburing/issues/1041 Fixes: fc68fcda0491 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-01-27 20:44:58 +00:00
#include "poll.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;
}
#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_BL_NO_RECYCLE;
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)
io_uring/rw: defer fsnotify calls to task context We can't call these off the kiocb completion as that might be off soft/hard irq context. Defer the calls to when we process the task_work for this request. That avoids valid complaints like: stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.0.0-rc6-syzkaller-00321-g105a36f3694e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_usage_bug kernel/locking/lockdep.c:3961 [inline] valid_state kernel/locking/lockdep.c:3973 [inline] mark_lock_irq kernel/locking/lockdep.c:4176 [inline] mark_lock.part.0.cold+0x18/0xd8 kernel/locking/lockdep.c:4632 mark_lock kernel/locking/lockdep.c:4596 [inline] mark_usage kernel/locking/lockdep.c:4527 [inline] __lock_acquire+0x11d9/0x56d0 kernel/locking/lockdep.c:5007 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 __fs_reclaim_acquire mm/page_alloc.c:4674 [inline] fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4688 might_alloc include/linux/sched/mm.h:271 [inline] slab_pre_alloc_hook mm/slab.h:700 [inline] slab_alloc mm/slab.c:3278 [inline] __kmem_cache_alloc_lru mm/slab.c:3471 [inline] kmem_cache_alloc+0x39/0x520 mm/slab.c:3491 fanotify_alloc_fid_event fs/notify/fanotify/fanotify.c:580 [inline] fanotify_alloc_event fs/notify/fanotify/fanotify.c:813 [inline] fanotify_handle_event+0x1130/0x3f40 fs/notify/fanotify/fanotify.c:948 send_to_group fs/notify/fsnotify.c:360 [inline] fsnotify+0xafb/0x1680 fs/notify/fsnotify.c:570 __fsnotify_parent+0x62f/0xa60 fs/notify/fsnotify.c:230 fsnotify_parent include/linux/fsnotify.h:77 [inline] fsnotify_file include/linux/fsnotify.h:99 [inline] fsnotify_access include/linux/fsnotify.h:309 [inline] __io_complete_rw_common+0x485/0x720 io_uring/rw.c:195 io_complete_rw+0x1a/0x1f0 io_uring/rw.c:228 iomap_dio_complete_work fs/iomap/direct-io.c:144 [inline] iomap_dio_bio_end_io+0x438/0x5e0 fs/iomap/direct-io.c:178 bio_endio+0x5f9/0x780 block/bio.c:1564 req_bio_endio block/blk-mq.c:695 [inline] blk_update_request+0x3fc/0x1300 block/blk-mq.c:825 scsi_end_request+0x7a/0x9a0 drivers/scsi/scsi_lib.c:541 scsi_io_completion+0x173/0x1f70 drivers/scsi/scsi_lib.c:971 scsi_complete+0x122/0x3b0 drivers/scsi/scsi_lib.c:1438 blk_complete_reqs+0xad/0xe0 block/blk-mq.c:1022 __do_softirq+0x1d3/0x9c6 kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650 irq_exit_rcu+0x5/0x20 kernel/softirq.c:662 common_interrupt+0xa9/0xc0 arch/x86/kernel/irq.c:240 Fixes: f63cf5192fe3 ("io_uring: ensure that fsnotify is always called") Link: https://lore.kernel.org/all/20220929135627.ykivmdks2w5vzrwg@quack3/ Reported-by: syzbot+dfcc5f4da15868df7d4d@syzkaller.appspotmail.com Reported-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-29 16:57:05 +00:00
{
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))
req->cqe.flags |= io_put_kbuf(req, 0);
io_req_task_complete(req, ts);
io_uring/rw: defer fsnotify calls to task context We can't call these off the kiocb completion as that might be off soft/hard irq context. Defer the calls to when we process the task_work for this request. That avoids valid complaints like: stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.0.0-rc6-syzkaller-00321-g105a36f3694e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_usage_bug kernel/locking/lockdep.c:3961 [inline] valid_state kernel/locking/lockdep.c:3973 [inline] mark_lock_irq kernel/locking/lockdep.c:4176 [inline] mark_lock.part.0.cold+0x18/0xd8 kernel/locking/lockdep.c:4632 mark_lock kernel/locking/lockdep.c:4596 [inline] mark_usage kernel/locking/lockdep.c:4527 [inline] __lock_acquire+0x11d9/0x56d0 kernel/locking/lockdep.c:5007 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 __fs_reclaim_acquire mm/page_alloc.c:4674 [inline] fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4688 might_alloc include/linux/sched/mm.h:271 [inline] slab_pre_alloc_hook mm/slab.h:700 [inline] slab_alloc mm/slab.c:3278 [inline] __kmem_cache_alloc_lru mm/slab.c:3471 [inline] kmem_cache_alloc+0x39/0x520 mm/slab.c:3491 fanotify_alloc_fid_event fs/notify/fanotify/fanotify.c:580 [inline] fanotify_alloc_event fs/notify/fanotify/fanotify.c:813 [inline] fanotify_handle_event+0x1130/0x3f40 fs/notify/fanotify/fanotify.c:948 send_to_group fs/notify/fsnotify.c:360 [inline] fsnotify+0xafb/0x1680 fs/notify/fsnotify.c:570 __fsnotify_parent+0x62f/0xa60 fs/notify/fsnotify.c:230 fsnotify_parent include/linux/fsnotify.h:77 [inline] fsnotify_file include/linux/fsnotify.h:99 [inline] fsnotify_access include/linux/fsnotify.h:309 [inline] __io_complete_rw_common+0x485/0x720 io_uring/rw.c:195 io_complete_rw+0x1a/0x1f0 io_uring/rw.c:228 iomap_dio_complete_work fs/iomap/direct-io.c:144 [inline] iomap_dio_bio_end_io+0x438/0x5e0 fs/iomap/direct-io.c:178 bio_endio+0x5f9/0x780 block/bio.c:1564 req_bio_endio block/blk-mq.c:695 [inline] blk_update_request+0x3fc/0x1300 block/blk-mq.c:825 scsi_end_request+0x7a/0x9a0 drivers/scsi/scsi_lib.c:541 scsi_io_completion+0x173/0x1f70 drivers/scsi/scsi_lib.c:971 scsi_complete+0x122/0x3b0 drivers/scsi/scsi_lib.c:1438 blk_complete_reqs+0xad/0xe0 block/blk-mq.c:1022 __do_softirq+0x1d3/0x9c6 kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650 irq_exit_rcu+0x5/0x20 kernel/softirq.c:662 common_interrupt+0xa9/0xc0 arch/x86/kernel/irq.c:240 Fixes: f63cf5192fe3 ("io_uring: ensure that fsnotify is always called") Link: https://lore.kernel.org/all/20220929135627.ykivmdks2w5vzrwg@quack3/ Reported-by: syzbot+dfcc5f4da15868df7d4d@syzkaller.appspotmail.com Reported-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-29 16:57:05 +00:00
}
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);
}
io_uring/rw: defer fsnotify calls to task context We can't call these off the kiocb completion as that might be off soft/hard irq context. Defer the calls to when we process the task_work for this request. That avoids valid complaints like: stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.0.0-rc6-syzkaller-00321-g105a36f3694e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_usage_bug kernel/locking/lockdep.c:3961 [inline] valid_state kernel/locking/lockdep.c:3973 [inline] mark_lock_irq kernel/locking/lockdep.c:4176 [inline] mark_lock.part.0.cold+0x18/0xd8 kernel/locking/lockdep.c:4632 mark_lock kernel/locking/lockdep.c:4596 [inline] mark_usage kernel/locking/lockdep.c:4527 [inline] __lock_acquire+0x11d9/0x56d0 kernel/locking/lockdep.c:5007 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 __fs_reclaim_acquire mm/page_alloc.c:4674 [inline] fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4688 might_alloc include/linux/sched/mm.h:271 [inline] slab_pre_alloc_hook mm/slab.h:700 [inline] slab_alloc mm/slab.c:3278 [inline] __kmem_cache_alloc_lru mm/slab.c:3471 [inline] kmem_cache_alloc+0x39/0x520 mm/slab.c:3491 fanotify_alloc_fid_event fs/notify/fanotify/fanotify.c:580 [inline] fanotify_alloc_event fs/notify/fanotify/fanotify.c:813 [inline] fanotify_handle_event+0x1130/0x3f40 fs/notify/fanotify/fanotify.c:948 send_to_group fs/notify/fsnotify.c:360 [inline] fsnotify+0xafb/0x1680 fs/notify/fsnotify.c:570 __fsnotify_parent+0x62f/0xa60 fs/notify/fsnotify.c:230 fsnotify_parent include/linux/fsnotify.h:77 [inline] fsnotify_file include/linux/fsnotify.h:99 [inline] fsnotify_access include/linux/fsnotify.h:309 [inline] __io_complete_rw_common+0x485/0x720 io_uring/rw.c:195 io_complete_rw+0x1a/0x1f0 io_uring/rw.c:228 iomap_dio_complete_work fs/iomap/direct-io.c:144 [inline] iomap_dio_bio_end_io+0x438/0x5e0 fs/iomap/direct-io.c:178 bio_endio+0x5f9/0x780 block/bio.c:1564 req_bio_endio block/blk-mq.c:695 [inline] blk_update_request+0x3fc/0x1300 block/blk-mq.c:825 scsi_end_request+0x7a/0x9a0 drivers/scsi/scsi_lib.c:541 scsi_io_completion+0x173/0x1f70 drivers/scsi/scsi_lib.c:971 scsi_complete+0x122/0x3b0 drivers/scsi/scsi_lib.c:1438 blk_complete_reqs+0xad/0xe0 block/blk-mq.c:1022 __do_softirq+0x1d3/0x9c6 kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650 irq_exit_rcu+0x5/0x20 kernel/softirq.c:662 common_interrupt+0xa9/0xc0 arch/x86/kernel/irq.c:240 Fixes: f63cf5192fe3 ("io_uring: ensure that fsnotify is always called") Link: https://lore.kernel.org/all/20220929135627.ykivmdks2w5vzrwg@quack3/ Reported-by: syzbot+dfcc5f4da15868df7d4d@syzkaller.appspotmail.com Reported-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-29 16:57:05 +00:00
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_BL_NO_RECYCLE;
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))
return -EAGAIN;
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 (io_file_can_poll(req) || !(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->f_mode & mode)))
return -EBADF;
if (!(req->flags & REQ_F_FIXED_FILE))
req->flags |= io_file_get_flags(file);
iov_iter work, part 1 - isolated cleanups and optimizations. One of the goals is to reduce the overhead of using ->read_iter() and ->write_iter() instead of ->read()/->write(); new_sync_{read,write}() has a surprising amount of overhead, in particular inside iocb_flags(). That's why the beginning of the series is in this pile; it's not directly iov_iter-related, but it's a part of the same work... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQQqUNBr3gm4hGXdBJlZ7Krx/gZQ6wUCYurGOQAKCRBZ7Krx/gZQ 6ysyAP91lvBfMRepcxpd9kvtuzWkU8A3rfSziZZteEHANB9Q7QEAiPn2a2OjWkcZ uAyUWfCkHCNx+dSMkEvUgR5okQ0exAM= =9UCV -----END PGP SIGNATURE----- Merge tag 'pull-work.iov_iter-base' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs iov_iter updates from Al Viro: "Part 1 - isolated cleanups and optimizations. One of the goals is to reduce the overhead of using ->read_iter() and ->write_iter() instead of ->read()/->write(). new_sync_{read,write}() has a surprising amount of overhead, in particular inside iocb_flags(). That's the explanation for the beginning of the series is in this pile; it's not directly iov_iter-related, but it's a part of the same work..." * tag 'pull-work.iov_iter-base' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: first_iovec_segment(): just return address iov_iter: massage calling conventions for first_{iovec,bvec}_segment() iov_iter: first_{iovec,bvec}_segment() - simplify a bit iov_iter: lift dealing with maxpages out of first_{iovec,bvec}_segment() iov_iter_get_pages{,_alloc}(): cap the maxsize with MAX_RW_COUNT iov_iter_bvec_advance(): don't bother with bvec_iter copy_page_{to,from}_iter(): switch iovec variants to generic keep iocb_flags() result cached in struct file iocb: delay evaluation of IS_SYNC(...) until we want to check IOCB_DSYNC struct file: use anonymous union member for rcuhead and llist btrfs: use IOMAP_DIO_NOSYNC teach iomap_dio_rw() to suppress dsync No need of likely/unlikely on calls of check_copy_size()
2022-08-03 20:50:22 +00:00
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 (io_file_can_poll(req) && !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 (!io_file_can_poll(req))
return -EBADFD;
ret = __io_read(req, issue_flags);
/*
* If the file doesn't support proper NOWAIT, then disable multishot
* and stay in single shot mode.
*/
if (!io_file_supports_nowait(req))
req->flags &= ~REQ_F_APOLL_MULTISHOT;
/*
* 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;
if (issue_flags & IO_URING_F_MULTISHOT)
return IOU_ISSUE_SKIP_COMPLETE;
return -EAGAIN;
}
/*
* Any successful return value will keep the multishot read armed.
*/
if (ret > 0 && req->flags & REQ_F_APOLL_MULTISHOT) {
/*
* 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_req_post_cqe(req, ret, cflags | IORING_CQE_F_MORE)) {
io_uring/rw: ensure poll based multishot read retries appropriately io_read_mshot() always relies on poll triggering retries, and this works fine as long as we do a retry per size of the buffer being read. The buffer size is given by the size of the buffer(s) in the given buffer group ID. But if we're reading less than what is available, then we don't always get to read everything that is available. For example, if the buffers available are 32 bytes and we have 64 bytes to read, then we'll correctly read the first 32 bytes and then wait for another poll trigger before we attempt the next read. This next poll trigger may never happen, in which case we just sit forever and never make progress, or it may trigger at some point in the future, and now we're just delivering the available data much later than we should have. io_read_mshot() could do retries itself, but that is wasteful as we'll be going through all of __io_read() again, and most likely in vain. Rather than do that, bump our poll reference count and have io_poll_check_events() do one more loop and check with vfs_poll() if we have more data to read. If we do, io_read_mshot() will get invoked again directly and we'll read the next chunk. io_poll_multishot_retry() must only get called from inside io_poll_issue(), which is our multishot retry handler, as we know we already "own" the request at this point. Cc: stable@vger.kernel.org Link: https://github.com/axboe/liburing/issues/1041 Fixes: fc68fcda0491 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-01-27 20:44:58 +00:00
if (issue_flags & IO_URING_F_MULTISHOT) {
/*
* Force retry, as we might have more data to
* be read and otherwise it won't get retried
* until (if ever) another poll is triggered.
*/
io_poll_multishot_retry(req);
return IOU_ISSUE_SKIP_COMPLETE;
io_uring/rw: ensure poll based multishot read retries appropriately io_read_mshot() always relies on poll triggering retries, and this works fine as long as we do a retry per size of the buffer being read. The buffer size is given by the size of the buffer(s) in the given buffer group ID. But if we're reading less than what is available, then we don't always get to read everything that is available. For example, if the buffers available are 32 bytes and we have 64 bytes to read, then we'll correctly read the first 32 bytes and then wait for another poll trigger before we attempt the next read. This next poll trigger may never happen, in which case we just sit forever and never make progress, or it may trigger at some point in the future, and now we're just delivering the available data much later than we should have. io_read_mshot() could do retries itself, but that is wasteful as we'll be going through all of __io_read() again, and most likely in vain. Rather than do that, bump our poll reference count and have io_poll_check_events() do one more loop and check with vfs_poll() if we have more data to read. If we do, io_read_mshot() will get invoked again directly and we'll read the next chunk. io_poll_multishot_retry() must only get called from inside io_poll_issue(), which is our multishot retry handler, as we know we already "own" the request at this point. Cc: stable@vger.kernel.org Link: https://github.com/axboe/liburing/issues/1041 Fixes: fc68fcda0491 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-01-27 20:44:58 +00:00
}
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;
}
ret = io_rw_init_file(req, FMODE_WRITE);
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)))
goto copy_iov;
/* File path supports NOWAIT for non-direct_IO only for block devices. */
if (!(kiocb->ki_flags & IOCB_DIRECT) &&
!(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) &&
(req->flags & REQ_F_ISREG))
goto copy_iov;
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(WRITE, req->file, ppos, req->cqe.res);
if (unlikely(ret)) {
kfree(iovec);
return ret;
}
if (req->flags & REQ_F_ISREG)
kiocb_start_write(kiocb);
kiocb->ki_flags |= IOCB_WRITE;
if (likely(req->file->f_op->write_iter))
ret2 = call_write_iter(req->file, kiocb, &s->iter);
else if (req->file->f_op->write)
ret2 = loop_rw_iter(WRITE, rw, &s->iter);
else
ret2 = -EINVAL;
if (req->flags & REQ_F_REISSUE) {
req->flags &= ~REQ_F_REISSUE;
ret2 = -EAGAIN;
}
/*
* Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just
* retry them without IOCB_NOWAIT.
*/
if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT))
ret2 = -EAGAIN;
/* no retry on NONBLOCK nor RWF_NOWAIT */
if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT))
goto done;
if (!force_nonblock || ret2 != -EAGAIN) {
/* IOPOLL retry should happen for io-wq threads */
if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL))
goto copy_iov;
if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) {
struct io_async_rw *io;
trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2,
req->cqe.res, ret2);
/* This is a partial write. The file pos has already been
* updated, setup the async struct to complete the request
* in the worker. Also update bytes_done to account for
* the bytes already written.
*/
iov_iter_save_state(&s->iter, &s->iter_state);
ret = io_setup_async_rw(req, iovec, s, true);
io = req->async_data;
if (io)
io->bytes_done += ret2;
if (kiocb->ki_flags & IOCB_WRITE)
io_req_end_write(req);
return ret ? ret : -EAGAIN;
}
done:
ret = kiocb_done(req, ret2, issue_flags);
} else {
copy_iov:
iov_iter_restore(&s->iter, &s->iter_state);
ret = io_setup_async_rw(req, iovec, s, false);
if (!ret) {
if (kiocb->ki_flags & IOCB_WRITE)
io_req_end_write(req);
return -EAGAIN;
}
return ret;
}
/* it's reportedly faster than delegating the null check to kfree() */
if (iovec)
kfree(iovec);
return ret;
}
void io_rw_fail(struct io_kiocb *req)
{
int res;
res = io_fixup_rw_res(req, req->cqe.res);
io_req_set_res(req, res, req->cqe.flags);
}
int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
{
struct io_wq_work_node *pos, *start, *prev;
unsigned int poll_flags = 0;
DEFINE_IO_COMP_BATCH(iob);
int nr_events = 0;
/*
* Only spin for completions if we don't have multiple devices hanging
* off our complete list.
*/
if (ctx->poll_multi_queue || force_nonspin)
poll_flags |= BLK_POLL_ONESHOT;
wq_list_for_each(pos, start, &ctx->iopoll_list) {
struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
struct file *file = req->file;
int ret;
/*
* Move completed and retryable entries to our local lists.
* If we find a request that requires polling, break out
* and complete those lists first, if we have entries there.
*/
if (READ_ONCE(req->iopoll_completed))
break;
if (req->opcode == IORING_OP_URING_CMD) {
struct io_uring_cmd *ioucmd;
ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
ret = file->f_op->uring_cmd_iopoll(ioucmd, &iob,
poll_flags);
} else {
struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
ret = file->f_op->iopoll(&rw->kiocb, &iob, poll_flags);
}
if (unlikely(ret < 0))
return ret;
else if (ret)
poll_flags |= BLK_POLL_ONESHOT;
/* iopoll may have completed current req */
if (!rq_list_empty(iob.req_list) ||
READ_ONCE(req->iopoll_completed))
break;
}
if (!rq_list_empty(iob.req_list))
iob.complete(&iob);
else if (!pos)
return 0;
prev = start;
wq_list_for_each_resume(pos, prev) {
struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
/* order with io_complete_rw_iopoll(), e.g. ->result updates */
if (!smp_load_acquire(&req->iopoll_completed))
break;
nr_events++;
req->cqe.flags = io_put_kbuf(req, 0);
}
if (unlikely(!nr_events))
return 0;
pos = start ? start->next : ctx->iopoll_list.first;
wq_list_cut(&ctx->iopoll_list, prev, start);
if (WARN_ON_ONCE(!wq_list_empty(&ctx->submit_state.compl_reqs)))
return 0;
ctx->submit_state.compl_reqs.first = pos;
__io_submit_flush_completions(ctx);
return nr_events;
}