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 fbc5c7b230b3..6cf516156111 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1152,3 +1152,21 @@ 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 16e554ba885d..7b175b9134ec 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -553,12 +553,13 @@ EXPORT_SYMBOL(vfs_write); 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) |