linux-kernel - [PATCH 18/18] flag parameters: NONBLOCK in inotify

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Date:	Sun, 4 May 2008 23:42:46 -0400
From:	Ulrich Drepper <drepper@...hat.com>
To:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Cc:	akpm@...ux-foundation.org, davidel@...ilserver.org,
	mtk.manpages@...il.com, torvalds@...ux-foundation.org
Subject: [PATCH 18/18] flag parameters: NONBLOCK in inotify_init

This patch adds non-blocking support for inotify_init1.  The
additional changes needed are minimal thanks to the previous preparation.

The following test must be adjusted for architectures other than x86 and
x86-64 and in case the syscall numbers changed.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>

#ifndef __NR_inotify_init1
# ifdef __x86_64__
#  define __NR_inotify_init1 294
# elif defined __i386__
#  define __NR_inotify_init1 332
# else
#  error "need __NR_inotify_init1"
# endif
#endif

#define IN_NONBLOCK (1 << 1)

int
main (void)
{
  int fd = syscall (__NR_inotify_init1, 0);
  if (fd == -1)
    {
      puts ("inotify_init1(0) failed");
      return 1;
    }
  int fl = fcntl (fd, F_GETFL);
  if (fl == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if (fl & O_NONBLOCK)
    {
      puts ("inotify_init1(0) set non-blocking mode");
      return 1;
    }
  close (fd);

  fd = syscall (__NR_inotify_init1, IN_NONBLOCK);
  if (fd == -1)
    {
      puts ("inotify_init1(IN_NONBLOCK) failed");
      return 1;
    }
  fl = fcntl (fd, F_GETFL);
  if (fl == -1)
    {
      puts ("fcntl failed");
      return 1;
    }
  if ((fl & O_NONBLOCK) == 0)
    {
      puts ("inotify_init1(IN_NONBLOCK) set non-blocking mode");
      return 1;
    }
  close (fd);

  puts ("OK");

  return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 fs/inotify_user.c       |    3 ++-
 include/linux/inotify.h |    1 +
 2 files changed, 3 insertions(+), 1 deletion(-)


Signed-off-by: Ulrich Drepper <drepper@...hat.com>

diff --git a/fs/inotify_user.c b/fs/inotify_user.c
index 6676c06..4bb4c54 100644
--- a/fs/inotify_user.c
+++ b/fs/inotify_user.c
@@ -569,6 +569,7 @@ static const struct inotify_operations inotify_user_ops = {
 
 static const struct flags_rmap inotify_file_flags_remap[] = {
         { IN_CLOEXEC, O_CLOEXEC },
+        { IN_NONBLOCK, O_NONBLOCK }
 };
 
 asmlinkage long sys_inotify_init1(int flags)
@@ -621,7 +622,7 @@ asmlinkage long sys_inotify_init(void)
 	filp->f_path.dentry = dget(inotify_mnt->mnt_root);
 	filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping;
 	filp->f_mode = FMODE_READ;
-	filp->f_flags = O_RDONLY;
+	filp->f_flags = O_RDONLY | (fflags & O_NONBLOCK);
 	filp->private_data = dev;
 
 	INIT_LIST_HEAD(&dev->events);
diff --git a/include/linux/inotify.h b/include/linux/inotify.h
index 742b917..af30cfd 100644
--- a/include/linux/inotify.h
+++ b/include/linux/inotify.h
@@ -65,6 +65,7 @@ struct inotify_event {
 
 /* Flags for sys_inotify_init1.  */
 #define IN_CLOEXEC (1 << 0)
+#define IN_NONBLOCK (1 << 1)
 
 #ifdef __KERNEL__
 
--
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