From fcb1620edd4d59eff4b3466be1d61263cea958a8 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Wed, 7 Feb 2024 11:43:32 -0800 Subject: [PATCH] bcachefs: thread_with_file: allow creation of readonly files Create a new run_thread_with_stdout function that opens a file in O_RDONLY mode so that the kernel can write things to userspace but userspace cannot write to the kernel. This will be used to convey xfs health event information to userspace. Signed-off-by: Darrick J. Wong Signed-off-by: Kent Overstreet --- fs/bcachefs/thread_with_file.c | 36 ++++++++++++++++++++++++++++++++++ fs/bcachefs/thread_with_file.h | 3 +++ 2 files changed, 39 insertions(+) diff --git a/fs/bcachefs/thread_with_file.c b/fs/bcachefs/thread_with_file.c index 96ac2b2c60e1..d1cd5f4ab06e 100644 --- a/fs/bcachefs/thread_with_file.c +++ b/fs/bcachefs/thread_with_file.c @@ -231,6 +231,22 @@ static __poll_t thread_with_stdio_poll(struct file *file, struct poll_table_stru return mask; } +static __poll_t thread_with_stdout_poll(struct file *file, struct poll_table_struct *wait) +{ + struct thread_with_stdio *thr = + container_of(file->private_data, struct thread_with_stdio, thr); + + poll_wait(file, &thr->stdio.output.wait, wait); + + __poll_t mask = 0; + + if (stdio_redirect_has_output(&thr->stdio)) + mask |= EPOLLIN; + if (thr->thr.done) + mask |= EPOLLHUP|EPOLLERR; + return mask; +} + static const struct file_operations thread_with_stdio_fops = { .llseek = no_llseek, .read = thread_with_stdio_read, @@ -239,6 +255,13 @@ static const struct file_operations thread_with_stdio_fops = { .release = thread_with_stdio_release, }; +static const struct file_operations thread_with_stdout_fops = { + .llseek = no_llseek, + .read = thread_with_stdio_read, + .poll = thread_with_stdout_poll, + .release = thread_with_stdio_release, +}; + static int thread_with_stdio_fn(void *arg) { struct thread_with_stdio *thr = arg; @@ -261,6 +284,19 @@ int bch2_run_thread_with_stdio(struct thread_with_stdio *thr, return bch2_run_thread_with_file(&thr->thr, &thread_with_stdio_fops, thread_with_stdio_fn); } +int bch2_run_thread_with_stdout(struct thread_with_stdio *thr, + void (*exit)(struct thread_with_stdio *), + void (*fn)(struct thread_with_stdio *)) +{ + stdio_buf_init(&thr->stdio.input); + stdio_buf_init(&thr->stdio.output); + thr->exit = exit; + thr->fn = fn; + + return bch2_run_thread_with_file(&thr->thr, &thread_with_stdout_fops, thread_with_stdio_fn); +} +EXPORT_SYMBOL_GPL(bch2_run_thread_with_stdout); + int bch2_stdio_redirect_read(struct stdio_redirect *stdio, char *ubuf, size_t len) { struct stdio_buf *buf = &stdio->input; diff --git a/fs/bcachefs/thread_with_file.h b/fs/bcachefs/thread_with_file.h index f06f8ff19a79..2b687723d6b9 100644 --- a/fs/bcachefs/thread_with_file.h +++ b/fs/bcachefs/thread_with_file.h @@ -59,6 +59,9 @@ struct thread_with_stdio { int bch2_run_thread_with_stdio(struct thread_with_stdio *, void (*exit)(struct thread_with_stdio *), void (*fn)(struct thread_with_stdio *)); +int bch2_run_thread_with_stdout(struct thread_with_stdio *, + void (*exit)(struct thread_with_stdio *), + void (*fn)(struct thread_with_stdio *)); int bch2_stdio_redirect_read(struct stdio_redirect *, char *, size_t); int bch2_stdio_redirect_readline(struct stdio_redirect *, char *, size_t);