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Shenoy" , K Prateek Nayak , Mateusz Guzik , Neeraj Upadhyay , Oliver Sang , Swapnil Sapkal , WangYuli , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/2] pipe: don't update {a,c,m}time for anonymous pipes Message-ID: <20250205181812.GC13817@redhat.com> References: <20250205181716.GA13817@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20250205181716.GA13817@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" These numbers are visible in fstat() but hopefully nobody uses this information and file_accessed/file_update_time are not that cheap. Stupid test-case: #include #include #include #include #include #include static char buf[17 * 4096]; static struct timeval TW, TR; int wr(int fd, int size) { int c, r; struct timeval t0, t1; gettimeofday(&t0, NULL); for (c =3D 0; (r =3D write(fd, buf, size)) > 0; c +=3D r); gettimeofday(&t1, NULL); timeradd(&TW, &t1, &TW); timersub(&TW, &t0, &TW); return c; } int rd(int fd, int size) { int c, r; struct timeval t0, t1; gettimeofday(&t0, NULL); for (c =3D 0; (r =3D read(fd, buf, size)) > 0; c +=3D r); gettimeofday(&t1, NULL); timeradd(&TR, &t1, &TR); timersub(&TR, &t0, &TR); return c; } int main(int argc, const char *argv[]) { int fd[2], nb =3D 1, loop, size; assert(argc =3D=3D 3); loop =3D atoi(argv[1]); size =3D atoi(argv[2]); assert(pipe(fd) =3D=3D 0); assert(ioctl(fd[0], FIONBIO, &nb) =3D=3D 0); assert(ioctl(fd[1], FIONBIO, &nb) =3D=3D 0); assert(size <=3D sizeof(buf)); while (loop--) assert(wr(fd[1], size) =3D=3D rd(fd[0], size)); struct timeval tt; timeradd(&TW, &TR, &tt); printf("TW =3D %lu.%03lu TR =3D %lu.%03lu TT =3D %lu.%03lu\n", TW.tv_sec, TW.tv_usec/1000, TR.tv_sec, TR.tv_usec/1000, tt.tv_sec, tt.tv_usec/1000); return 0; } Before: # for i in 1 2 3; do /host/tmp/test 10000 100; done TW =3D 8.047 TR =3D 5.845 TT =3D 13.893 TW =3D 8.091 TR =3D 5.872 TT =3D 13.963 TW =3D 8.083 TR =3D 5.885 TT =3D 13.969 After: # for i in 1 2 3; do /host/tmp/test 10000 100; done TW =3D 4.752 TR =3D 4.664 TT =3D 9.416 TW =3D 4.684 TR =3D 4.608 TT =3D 9.293 TW =3D 4.736 TR =3D 4.652 TT =3D 9.388 Signed-off-by: Oleg Nesterov --- fs/pipe.c | 41 +++++++++++++++++++++++++++++------------ 1 file changed, 29 insertions(+), 12 deletions(-) diff --git a/fs/pipe.c b/fs/pipe.c index 2eacfde61e74..2ae75adfba64 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -248,7 +248,7 @@ static inline unsigned int pipe_update_tail(struct pipe= _inode_info *pipe, } =20 static ssize_t -pipe_read(struct kiocb *iocb, struct iov_iter *to) +anon_pipe_read(struct kiocb *iocb, struct iov_iter *to) { size_t total_len =3D iov_iter_count(to); struct file *filp =3D iocb->ki_filp; @@ -404,8 +404,15 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) if (wake_next_reader) wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM); kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); + return ret; +} + +static ssize_t +fifo_pipe_read(struct kiocb *iocb, struct iov_iter *to) +{ + int ret =3D anon_pipe_read(iocb, to); if (ret > 0) - file_accessed(filp); + file_accessed(iocb->ki_filp); return ret; } =20 @@ -426,7 +433,7 @@ static inline bool pipe_writable(const struct pipe_inod= e_info *pipe) } =20 static ssize_t -pipe_write(struct kiocb *iocb, struct iov_iter *from) +anon_pipe_write(struct kiocb *iocb, struct iov_iter *from) { struct file *filp =3D iocb->ki_filp; struct pipe_inode_info *pipe =3D filp->private_data; @@ -604,11 +611,21 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); if (wake_next_writer) wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM); - if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) { - int err =3D file_update_time(filp); - if (err) - ret =3D err; - sb_end_write(file_inode(filp)->i_sb); + return ret; +} + +static ssize_t +fifo_pipe_write(struct kiocb *iocb, struct iov_iter *from) +{ + int ret =3D anon_pipe_write(iocb, from); + if (ret > 0) { + struct file *filp =3D iocb->ki_filp; + if (sb_start_write_trylock(file_inode(filp)->i_sb)) { + int err =3D file_update_time(filp); + if (err) + ret =3D err; + sb_end_write(file_inode(filp)->i_sb); + } } return ret; } @@ -1234,8 +1251,8 @@ static int fifo_open(struct inode *inode, struct file= *filp) =20 const struct file_operations pipefifo_fops =3D { .open =3D fifo_open, - .read_iter =3D pipe_read, - .write_iter =3D pipe_write, + .read_iter =3D fifo_pipe_read, + .write_iter =3D fifo_pipe_write, .poll =3D pipe_poll, .unlocked_ioctl =3D pipe_ioctl, .release =3D pipe_release, @@ -1245,8 +1262,8 @@ const struct file_operations pipefifo_fops =3D { =20 static const struct file_operations pipeanon_fops =3D { .open =3D fifo_open, - .read_iter =3D pipe_read, - .write_iter =3D pipe_write, + .read_iter =3D anon_pipe_read, + .write_iter =3D anon_pipe_write, .poll =3D pipe_poll, .unlocked_ioctl =3D pipe_ioctl, .release =3D pipe_release, --=20 2.25.1.362.g51ebf55