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>

1 files changed, 15 insertions, 23 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
index 105b0021b075..357471db890d 100644
--- 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;
 }