[PATCH 05/29] vfs: add a vfs helper for io_uring file pos lock
From: Hao Xu <hidden>
Date: 2023-08-25 13:58:07
Also in:
bpf, linux-block, linux-btrfs, linux-cifs, linux-ext4, linux-f2fs-devel, linux-fsdevel, linux-mm, linux-nfs, linux-s390, linux-unionfs, linux-xfs, lkml, netdev
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
From: Hao Xu <redacted> Add a vfs helper file_pos_lock_nowait() for io_uring usage. The function have conditional nowait logic, i.e. if nowait is needed, return -EAGAIN when trylock fails. Signed-off-by: Hao Xu <redacted> --- fs/file.c | 13 +++++++++++++ include/linux/file.h | 2 ++ 2 files changed, 15 insertions(+)
diff --git a/fs/file.c b/fs/file.c
index 35c62b54c9d6..8e5c38f5db52 100644
--- a/fs/file.c
+++ b/fs/file.c@@ -1053,6 +1053,19 @@ void __f_unlock_pos(struct file *f) mutex_unlock(&f->f_pos_lock); } +int file_pos_lock_nowait(struct file *file, bool nowait) +{ + if (!(file->f_mode & FMODE_ATOMIC_POS)) + return 0; + + if (!nowait) + mutex_lock(&file->f_pos_lock); + else if (!mutex_trylock(&file->f_pos_lock)) + return -EAGAIN; + + return 1; +} + /* * We only lock f_pos if we have threads or if the file might be * shared with another process. In both cases we'll have an elevated
diff --git a/include/linux/file.h b/include/linux/file.h
index 6e9099d29343..bcc6ba0aec50 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h@@ -81,6 +81,8 @@ static inline void fdput_pos(struct fd f) fdput(f); } +extern int file_pos_lock_nowait(struct file *file, bool nowait); + DEFINE_CLASS(fd, struct fd, fdput(_T), fdget(fd), int fd) extern int f_dupfd(unsigned int from, struct file *file, unsigned flags);
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2.25.1