pipe: move limit checking logic into pipe_set_size()

This is a preparatory patch for following work. Move the F_SETPIPE_SZ
limit-checking logic from pipe_fcntl() into pipe_set_size().  This
simplifies the code a little, and allows for reworking required in
a later patch that fixes the limit checking in pipe_set_size()

Link: http://lkml.kernel.org/r/3701b2c5-2c52-2c3e-226d-29b9deb29b50@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 18 insertions, 23 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
index 8773ecaa44b5..a72b6ff9b48a 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1023,9 +1023,24 @@ static inline unsigned int round_pipe_size(unsigned int size)
  * Allocate a new array of pipe buffers and copy the info over. Returns the
  * pipe size if successful, or return -ERROR on error.
  */
-static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
+static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
 {
         struct pipe_buffer *bufs;
+        unsigned int size, nr_pages;
+
+        size = round_pipe_size(arg);
+        nr_pages = size >> PAGE_SHIFT;
+
+        if (!nr_pages)
+                return -EINVAL;
+
+        if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size)
+                return -EPERM;
+
+        if ((too_many_pipe_buffers_hard(pipe->user) ||
+                        too_many_pipe_buffers_soft(pipe->user)) &&
+                        !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
+                return -EPERM;
 
         /*
          * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
@@ -1109,28 +1124,9 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
         __pipe_lock(pipe);
 
         switch (cmd) {
-        case F_SETPIPE_SZ: {
-                unsigned int size, nr_pages;
-
-                size = round_pipe_size(arg);
-                nr_pages = size >> PAGE_SHIFT;
-
-                ret = -EINVAL;
-                if (!nr_pages)
-                        goto out;
-
-                if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
-                        ret = -EPERM;
-                        goto out;
-                } else if ((too_many_pipe_buffers_hard(pipe->user) ||
-                            too_many_pipe_buffers_soft(pipe->user)) &&
-                           !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
-                        ret = -EPERM;
-                        goto out;
-                }
-                ret = pipe_set_size(pipe, nr_pages);
+        case F_SETPIPE_SZ:
+                ret = pipe_set_size(pipe, arg);
                 break;
-                }
         case F_GETPIPE_SZ:
                 ret = pipe->buffers * PAGE_SIZE;
                 break;
@@ -1139,7 +1135,6 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
                 break;
         }
 
-out:
         __pipe_unlock(pipe);
         return ret;
 }