diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/open.c | 18 | ||||
| -rw-r--r-- | fs/read_write.c | 5 |
2 files changed, 21 insertions, 2 deletions
diff --git a/fs/open.c b/fs/open.c index 28a3956c4479..f4ea0dc88823 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1212,3 +1212,21 @@ int nonseekable_open(struct inode *inode, struct file *filp) } EXPORT_SYMBOL(nonseekable_open); + +/* + * stream_open is used by subsystems that want stream-like file descriptors. + * Such file descriptors are not seekable and don't have notion of position + * (file.f_pos is always 0). Contrary to file descriptors of other regular + * files, .read() and .write() can run simultaneously. + * + * stream_open never fails and is marked to return int so that it could be + * directly used as file_operations.open . + */ +int stream_open(struct inode *inode, struct file *filp) +{ + filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS); + filp->f_mode |= FMODE_STREAM; + return 0; +} + +EXPORT_SYMBOL(stream_open); diff --git a/fs/read_write.c b/fs/read_write.c index 1c3eada2fe25..d6f8bfb0f794 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -555,12 +555,13 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_ static inline loff_t file_pos_read(struct file *file) { - return file->f_pos; + return file->f_mode & FMODE_STREAM ? 0 : file->f_pos; } static inline void file_pos_write(struct file *file, loff_t pos) { - file->f_pos = pos; + if ((file->f_mode & FMODE_STREAM) == 0) + file->f_pos = pos; } SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) |