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timerfd: convert to ->read_iter()

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Switch timerfd to using fops->read_iter(), so it can support not just
O_NONBLOCK but IOCB_NOWAIT as well. With the latter, users like io_uring
interact with timerfds a lot better, as they can be driven purely
by the poll trigger.

Manually get and install the required fd, so that FMODE_NOWAIT can be
set before the file is installed into the file table.

No functional changes intended in this patch, it's purely a straight
conversion to using the read iterator method.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2024-04-01 11:48:37 -06:00
parent 1f65f52d13
commit d949799041
1 changed files with 26 additions and 10 deletions
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36
fs/timerfd.c
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@ -262,17 +262,18 @@ static __poll_t timerfd_poll(struct file *file, poll_table *wait)
return events;
}
static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
loff_t *ppos)
static ssize_t timerfd_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct timerfd_ctx *ctx = file->private_data;
ssize_t res;
u64 ticks = 0;
if (count < sizeof(ticks))
if (iov_iter_count(to) < sizeof(ticks))
return -EINVAL;
spin_lock_irq(&ctx->wqh.lock);
if (file->f_flags & O_NONBLOCK)
if (file->f_flags & O_NONBLOCK || iocb->ki_flags & IOCB_NOWAIT)
res = -EAGAIN;
else
res = wait_event_interruptible_locked_irq(ctx->wqh, ctx->ticks);
@ -312,8 +313,11 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
ctx->ticks = 0;
}
spin_unlock_irq(&ctx->wqh.lock);
if (ticks)
res = put_user(ticks, (u64 __user *) buf) ? -EFAULT: sizeof(ticks);
if (ticks) {
res = copy_to_iter(&ticks, sizeof(ticks), to);
if (!res)
res = -EFAULT;
}
return res;
}
@ -384,7 +388,7 @@ static long timerfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg
static const struct file_operations timerfd_fops = {
.release = timerfd_release,
.poll = timerfd_poll,
.read = timerfd_read,
.read_iter = timerfd_read_iter,
.llseek = noop_llseek,
.show_fdinfo = timerfd_show,
.unlocked_ioctl = timerfd_ioctl,
@ -407,6 +411,7 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
{
int ufd;
struct timerfd_ctx *ctx;
struct file *file;
/* Check the TFD_* constants for consistency. */
BUILD_BUG_ON(TFD_CLOEXEC != O_CLOEXEC);
@ -443,11 +448,22 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
ctx->moffs = ktime_mono_to_real(0);
ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));
if (ufd < 0)
ufd = get_unused_fd_flags(flags & TFD_SHARED_FCNTL_FLAGS);
if (ufd < 0) {
kfree(ctx);
return ufd;
}
file = anon_inode_getfile("[timerfd]", &timerfd_fops, ctx,
O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));
if (IS_ERR(file)) {
put_unused_fd(ufd);
kfree(ctx);
return PTR_ERR(file);
}
file->f_mode |= FMODE_NOWAIT;
fd_install(ufd, file);
return ufd;
}