[PATCH] splice: fix problem introduced with inode diet

After the inode slimming patch that unionised i_pipe/i_bdev/i_cdev, it's
no longer enough to check for existance of ->i_pipe to verify that this
is a pipe.

Original patch from Eric Dumazet <dada1@cosmosbay.com>
Final solution suggested by Linus.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 20 insertions, 6 deletions

diff --git a/fs/splice.c b/fs/splice.c
index 8d705954d294..da74583a00ee 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1109,6 +1109,19 @@ out_release:
 EXPORT_SYMBOL(do_splice_direct);
 
 /*
+ * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
+ * location, so checking ->i_pipe is not enough to verify that this is a
+ * pipe.
+ */
+static inline struct pipe_inode_info *pipe_info(struct inode *inode)
+{
+        if (S_ISFIFO(inode->i_mode))
+                return inode->i_pipe;
+
+        return NULL;
+}
+
+/*
  * Determine where to splice to/from.
  */
 static long do_splice(struct file *in, loff_t __user *off_in,
@@ -1119,7 +1132,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
         loff_t offset, *off;
         long ret;
 
-        pipe = in->f_dentry->d_inode->i_pipe;
+        pipe = pipe_info(in->f_dentry->d_inode);
         if (pipe) {
                 if (off_in)
                         return -ESPIPE;
@@ -1140,7 +1153,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
                 return ret;
         }
 
-        pipe = out->f_dentry->d_inode->i_pipe;
+        pipe = pipe_info(out->f_dentry->d_inode);
         if (pipe) {
                 if (off_out)
                         return -ESPIPE;
@@ -1298,7 +1311,7 @@ static int get_iovec_page_array(const struct iovec __user *iov,
 static long do_vmsplice(struct file *file, const struct iovec __user *iov,
                         unsigned long nr_segs, unsigned int flags)
 {
-        struct pipe_inode_info *pipe = file->f_dentry->d_inode->i_pipe;
+        struct pipe_inode_info *pipe;
         struct page *pages[PIPE_BUFFERS];
         struct partial_page partial[PIPE_BUFFERS];
         struct splice_pipe_desc spd = {
@@ -1308,7 +1321,8 @@ static long do_vmsplice(struct file *file, const struct iovec __user *iov,
                 .ops = &user_page_pipe_buf_ops,
         };
 
-        if (unlikely(!pipe))
+        pipe = pipe_info(file->f_dentry->d_inode);
+        if (!pipe)
                 return -EBADF;
         if (unlikely(nr_segs > UIO_MAXIOV))
                 return -EINVAL;
@@ -1535,8 +1549,8 @@ static int link_pipe(struct pipe_inode_info *ipipe,
 static long do_tee(struct file *in, struct file *out, size_t len,
                    unsigned int flags)
 {
-        struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
-        struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
+        struct pipe_inode_info *ipipe = pipe_info(in->f_dentry->d_inode);
+        struct pipe_inode_info *opipe = pipe_info(out->f_dentry->d_inode);
         int ret = -EINVAL;
 
         /*