| Message ID | 1428858502-5371-2-git-send-email-dmonakhov@openvz.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Apr 12, 2015 at 09:08:21PM +0400, Dmitry Monakhov wrote: > Fix other long standing issues caused by fcntl(,F_SETFL,): > - User can disable O_DIRECT for pipe[1] (paketized IO), but can not enable it again. > - Currently we do not set O_APPEND on pipe[1] (IMHO it is wrong, but let it be) > so it is reasonable to completely prohibit change O_APPEND flag on both > end's of pipe. Add ->check_flags method in order to diallow O_APPEND toggling. > > Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> > --- TBH, all those ->direct_IO != NULL checks seem to be a wrong approach. If nothing else, it forces several filesystem into inventing a fake ->direct_IO just to fool those tests. How about we * introduce FMODE_MAY_DIRECT and allow ->open() explicitly set it * make open_check_o_direct() and fcntl.c check that instead of poking in ->f_mapping->a_ops, etc. * provide a variant of generic_file_open() that would set that bit and use it on the filesystems that handle dio -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Al Viro <viro@ZenIV.linux.org.uk> writes: > On Sun, Apr 12, 2015 at 09:08:21PM +0400, Dmitry Monakhov wrote: >> Fix other long standing issues caused by fcntl(,F_SETFL,): >> - User can disable O_DIRECT for pipe[1] (paketized IO), but can not enable it again. >> - Currently we do not set O_APPEND on pipe[1] (IMHO it is wrong, but let it be) >> so it is reasonable to completely prohibit change O_APPEND flag on both >> end's of pipe. Add ->check_flags method in order to diallow O_APPEND toggling. >> >> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> >> --- > > TBH, all those ->direct_IO != NULL checks seem to be a wrong approach. > If nothing else, it forces several filesystem into inventing a fake > ->direct_IO just to fool those tests. How about we > * introduce FMODE_MAY_DIRECT and allow ->open() explicitly set it > * make open_check_o_direct() and fcntl.c check that instead of poking > in ->f_mapping->a_ops, etc. > * provide a variant of generic_file_open() that would set that > bit and use it on the filesystems that handle dio 100% agree. FMODE is perfect place for that. BTW: I always wondering: why we do not mark pipe[1]->f_flags with O_APPEND? Probably the answer is that nobody care about ->f_flags since no_llseek returns -ESPIPE, but f_flags are visiable via fcntl so IMHO it is reasonable to fix that too. > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/fcntl.c b/fs/fcntl.c index ee85cd4..0bdc9c7 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -51,9 +51,11 @@ static int setfl(int fd, struct file * filp, unsigned long arg) if (arg & O_NDELAY) arg |= O_NONBLOCK; + /* allowed only for inodes with ->direct_io method or write pipe */ if (arg & O_DIRECT) { - if (!filp->f_mapping || !filp->f_mapping->a_ops || - !filp->f_mapping->a_ops->direct_IO) + if ((!filp->f_mapping || !filp->f_mapping->a_ops || + !filp->f_mapping->a_ops->direct_IO) && + !(get_pipe_info(filp) && (filp->f_flags | O_WRONLY))) return -EINVAL; } diff --git a/fs/pipe.c b/fs/pipe.c index 8865f79..0c15647 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -329,9 +329,9 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) return ret; } -static inline int is_packetized(struct file *file) +static inline int is_packetized(struct kiocb *iocb) { - return (file->f_flags & O_DIRECT) != 0; + return (iocb->ki_flags & IOCB_DIRECT) != 0; } static ssize_t @@ -427,7 +427,7 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) buf->offset = 0; buf->len = copied; buf->flags = 0; - if (is_packetized(filp)) { + if (is_packetized(iocb)) { buf->ops = &packet_pipe_buf_ops; buf->flags = PIPE_BUF_FLAG_PACKET; } @@ -943,6 +943,15 @@ err: return ret; } +/* XXX: Currently it is not possible distinguish read side from write one */ +static int pipe_check_flags(int flags) +{ + if (flags & O_APPEND) + return -EINVAL; + + return 0; +} + const struct file_operations pipefifo_fops = { .open = fifo_open, .llseek = no_llseek, @@ -952,6 +961,7 @@ const struct file_operations pipefifo_fops = { .unlocked_ioctl = pipe_ioctl, .release = pipe_release, .fasync = pipe_fasync, + .check_flags = pipe_check_flags, }; /*
Fix other long standing issues caused by fcntl(,F_SETFL,): - User can disable O_DIRECT for pipe[1] (paketized IO), but can not enable it again. - Currently we do not set O_APPEND on pipe[1] (IMHO it is wrong, but let it be) so it is reasonable to completely prohibit change O_APPEND flag on both end's of pipe. Add ->check_flags method in order to diallow O_APPEND toggling. Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> --- fs/fcntl.c | 6 ++++-- fs/pipe.c | 16 +++++++++++++--- 2 files changed, 17 insertions(+), 5 deletions(-)