pipe: preparation to new locking rules

* use the fact that file_inode(file)->i_pipe doesn't change
  while the file is opened - no locks needed to access that.
* switch to pipe_lock/pipe_unlock where it's easy to do

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/pipe.c b/fs/pipe.c
index 105b002..357471d 100644 (file)
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -363,8 +363,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
           unsigned long nr_segs, loff_t pos)
 {
        struct file *filp = iocb->ki_filp;
-       struct inode *inode = file_inode(filp);
-       struct pipe_inode_info *pipe;
+       struct pipe_inode_info *pipe = file_inode(filp)->i_pipe;
        int do_wakeup;
        ssize_t ret;
        struct iovec *iov = (struct iovec *)_iov;
@@ -377,8 +376,7 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
 
        do_wakeup = 0;
        ret = 0;
-       mutex_lock(&inode->i_mutex);
-       pipe = inode->i_pipe;
+       pipe_lock(pipe);
        for (;;) {
                int bufs = pipe->nrbufs;
                if (bufs) {
@@ -466,7 +464,7 @@ redo:
                }
                pipe_wait(pipe);
        }
-       mutex_unlock(&inode->i_mutex);
+       pipe_unlock(pipe);
 
        /* Signal writers asynchronously that there is more room. */
        if (do_wakeup) {
@@ -488,8 +486,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
            unsigned long nr_segs, loff_t ppos)
 {
        struct file *filp = iocb->ki_filp;
-       struct inode *inode = file_inode(filp);
-       struct pipe_inode_info *pipe;
+       struct pipe_inode_info *pipe = file_inode(filp)->i_pipe;
        ssize_t ret;
        int do_wakeup;
        struct iovec *iov = (struct iovec *)_iov;
@@ -503,8 +500,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
 
        do_wakeup = 0;
        ret = 0;
-       mutex_lock(&inode->i_mutex);
-       pipe = inode->i_pipe;
+       pipe_lock(pipe);
 
        if (!pipe->readers) {
                send_sig(SIGPIPE, current, 0);
@@ -651,7 +647,7 @@ redo2:
                pipe->waiting_writers--;
        }
 out:
-       mutex_unlock(&inode->i_mutex);
+       pipe_unlock(pipe);
        if (do_wakeup) {
                wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
                kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
@@ -666,14 +662,12 @@ out:
 
 static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
-       struct inode *inode = file_inode(filp);
-       struct pipe_inode_info *pipe;
+       struct pipe_inode_info *pipe = file_inode(filp)->i_pipe;
        int count, buf, nrbufs;
 
        switch (cmd) {
                case FIONREAD:
-                       mutex_lock(&inode->i_mutex);
-                       pipe = inode->i_pipe;
+                       pipe_lock(pipe);
                        count = 0;
                        buf = pipe->curbuf;
                        nrbufs = pipe->nrbufs;
@@ -681,7 +675,7 @@ static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
                                count += pipe->bufs[buf].len;
                                buf = (buf+1) & (pipe->buffers - 1);
                        }
-                       mutex_unlock(&inode->i_mutex);
+                       pipe_unlock(pipe);
 
                        return put_user(count, (int __user *)arg);
                default:
@@ -694,8 +688,7 @@ static unsigned int
 pipe_poll(struct file *filp, poll_table *wait)
 {
        unsigned int mask;
-       struct inode *inode = file_inode(filp);
-       struct pipe_inode_info *pipe = inode->i_pipe;
+       struct pipe_inode_info *pipe = file_inode(filp)->i_pipe;
        int nrbufs;
 
        poll_wait(filp, &pipe->wait, wait);
@@ -749,11 +742,10 @@ pipe_release(struct inode *inode, struct file *file)
 static int
 pipe_fasync(int fd, struct file *filp, int on)
 {
-       struct inode *inode = file_inode(filp);
-       struct pipe_inode_info *pipe = inode->i_pipe;
+       struct pipe_inode_info *pipe = file_inode(filp)->i_pipe;
        int retval = 0;
 
-       mutex_lock(&inode->i_mutex);
+       pipe_lock(pipe);
        if (filp->f_mode & FMODE_READ)
                retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
        if ((filp->f_mode & FMODE_WRITE) && retval >= 0) {
@@ -762,7 +754,7 @@ pipe_fasync(int fd, struct file *filp, int on)
                        /* this can happen only if on == T */
                        fasync_helper(-1, filp, 0, &pipe->fasync_readers);
        }
-       mutex_unlock(&inode->i_mutex);
+       pipe_unlock(pipe);
        return retval;
 }
 
@@ -1224,7 +1216,7 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
        if (!pipe)
                return -EBADF;
 
-       mutex_lock(&pipe->inode->i_mutex);
+       pipe_lock(pipe);
 
        switch (cmd) {
        case F_SETPIPE_SZ: {
@@ -1253,7 +1245,7 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
        }
 
 out:
-       mutex_unlock(&pipe->inode->i_mutex);
+       pipe_unlock(pipe);
        return ret;
 }