[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>

diff --git a/fs/namei.c b/fs/namei.c
index 8cf9bb9c2fc0b0133d85f0f6ff0f3e35a9fb8e07..c70dbf72010968aa2f903a3f24d585c6570d5220 100644 (file)
--- 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;
@@ -1695,27 +1700,47 @@ static int open_namei_create(struct nameidata *nd, struct path *path,
        return may_open(nd, 0, flag & ~O_TRUNC);
 }
 
+/*
+ * 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;

diff --git a/fs/open.c b/fs/open.c
index 3fa4e4ffce4cb4ba69862703f90d289731809eab..5ab3f3f079c068e0b4a3cab6c2f0058f394468e0 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -796,31 +796,13 @@ cleanup_file:
        return ERR_PTR(error);
 }
 
-/*
- * 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). 00 is
- * used by symlinks.
- */
 static struct file *do_filp_open(int dfd, const char *filename, int flags,
                                 int mode)
 {
-       int namei_flags, error;
+       int error;
        struct nameidata nd;
 
-       namei_flags = flags;
-       if ((namei_flags+1) & O_ACCMODE)
-               namei_flags++;
-
-       error = open_namei(dfd, filename, namei_flags, mode, &nd);
+       error = open_namei(dfd, filename, flags, mode, &nd);
        if (!error)
                return nameidata_to_filp(&nd, flags);