[PATCH] do namei_flags calculation inside open_namei()

My end goal here is to make sure all users of may_open()
return filps.  This will ensure that we properly release
mount write counts which were taken for the filp in
may_open().

This patch moves the sys_open flags to namei flags
calculation into fs/namei.c.  We'll shortly be moving
the nameidata_to_filp() calls into namei.c, and this
gets the sys_open flags to a place where we can get
at them when we need them.

Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 34 insertions, 9 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 8cf9bb9c2fc0..c70dbf720109 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1677,7 +1677,12 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
         return 0;
 }
 
-static int open_namei_create(struct nameidata *nd, struct path *path,
+/*
+ * Be careful about ever adding any more callers of this
+ * function.  Its flags must be in the namei format, not
+ * what get passed to sys_open().
+ */
+static int __open_namei_create(struct nameidata *nd, struct path *path,
                                 int flag, int mode)
 {
         int error;
@@ -1696,26 +1701,46 @@ static int open_namei_create(struct nameidata *nd, struct path *path,
 }
 
 /*
+ * Note that while the flag value (low two bits) for sys_open means:
+ *      00 - read-only
+ *      01 - write-only
+ *      10 - read-write
+ *      11 - special
+ * it is changed into
+ *      00 - no permissions needed
+ *      01 - read-permission
+ *      10 - write-permission
+ *      11 - read-write
+ * for the internal routines (ie open_namei()/follow_link() etc)
+ * This is more logical, and also allows the 00 "no perm needed"
+ * to be used for symlinks (where the permissions are checked
+ * later).
+ *
+*/
+static inline int open_to_namei_flags(int flag)
+{
+        if ((flag+1) & O_ACCMODE)
+                flag++;
+        return flag;
+}
+
+/*
  *      open_namei()
  *
  * namei for open - this is in fact almost the whole open-routine.
  *
  * Note that the low bits of "flag" aren't the same as in the open
- * system call - they are 00 - no permissions needed
- *                        01 - read permission needed
- *                        10 - write permission needed
- *                        11 - read/write permissions needed
- * which is a lot more logical, and also allows the "no perm" needed
- * for symlinks (where the permissions are checked later).
+ * system call.  See open_to_namei_flags().
  * SMP-safe
  */
-int open_namei(int dfd, const char *pathname, int flag,
+int open_namei(int dfd, const char *pathname, int open_flag,
                 int mode, struct nameidata *nd)
 {
         int acc_mode, error;
         struct path path;
         struct dentry *dir;
         int count = 0;
+        int flag = open_to_namei_flags(open_flag);
 
         acc_mode = ACC_MODE(flag);
 
@@ -1776,7 +1801,7 @@ do_last:
 
         /* Negative dentry, just create the file */
         if (!path.dentry->d_inode) {
-                error = open_namei_create(nd, &path, flag, mode);
+                error = __open_namei_create(nd, &path, flag, mode);
                 if (error)
                         goto exit;
                 return 0;