1cbae651e5
Experimentally fix some problems with stdio_redirect_vprintf by creating a MOO variant with which we can experiment. We can't do a GFP_KERNEL allocation while holding the spinlock, and I don't like how the printf function can silently truncate the output if memory allocation fails. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
72 lines
2.6 KiB
C
72 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _BCACHEFS_THREAD_WITH_FILE_H
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#define _BCACHEFS_THREAD_WITH_FILE_H
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#include "thread_with_file_types.h"
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/*
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* Thread with file: Run a kthread and connect it to a file descriptor, so that
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* it can be interacted with via fd read/write methods and closing the file
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* descriptor stops the kthread.
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*
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* We have two different APIs:
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*
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* thread_with_file, the low level version.
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* You get to define the full file_operations, including your release function,
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* which means that you must call bch2_thread_with_file_exit() from your
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* .release method
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*
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* thread_with_stdio, the higher level version
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* This implements full piping of input and output, including .poll.
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*
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* Notes on behaviour:
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* - kthread shutdown behaves like writing or reading from a pipe that has been
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* closed
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* - Input and output buffers are 4096 bytes, although buffers may in some
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* situations slightly exceed that limit so as to avoid chopping off a
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* message in the middle in nonblocking mode.
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* - Input/output buffers are lazily allocated, with GFP_NOWAIT allocations -
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* should be fine but might change in future revisions.
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* - Output buffer may grow past 4096 bytes to deal with messages that are
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* bigger than 4096 bytes
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* - Writing may be done blocking or nonblocking; in nonblocking mode, we only
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* drop entire messages.
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*
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* To write, use stdio_redirect_printf()
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* To read, use stdio_redirect_read() or stdio_redirect_readline()
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*/
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struct task_struct;
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struct thread_with_file {
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struct task_struct *task;
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int ret;
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bool done;
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};
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void bch2_thread_with_file_exit(struct thread_with_file *);
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int bch2_run_thread_with_file(struct thread_with_file *,
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const struct file_operations *,
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int (*fn)(void *));
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struct thread_with_stdio {
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struct thread_with_file thr;
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struct stdio_redirect stdio;
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void (*exit)(struct thread_with_stdio *);
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void (*fn)(struct thread_with_stdio *);
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};
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int bch2_run_thread_with_stdio(struct thread_with_stdio *,
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void (*exit)(struct thread_with_stdio *),
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void (*fn)(struct thread_with_stdio *));
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int bch2_run_thread_with_stdout(struct thread_with_stdio *,
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void (*exit)(struct thread_with_stdio *),
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void (*fn)(struct thread_with_stdio *));
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int bch2_stdio_redirect_read(struct stdio_redirect *, char *, size_t);
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int bch2_stdio_redirect_readline(struct stdio_redirect *, char *, size_t);
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__printf(3, 0) ssize_t bch2_stdio_redirect_vprintf(struct stdio_redirect *, bool, const char *, va_list);
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__printf(3, 4) ssize_t bch2_stdio_redirect_printf(struct stdio_redirect *, bool, const char *, ...);
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#endif /* _BCACHEFS_THREAD_WITH_FILE_H */
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