[PATCH] merge open_namei() and do_filp_open()

open_namei() will, in the future, need to take mount write counts
over its creation and truncation (via may_open()) operations.  It
needs to keep these write counts until any potential filp that is
created gets __fput()'d.

This gets complicated in the error handling and becomes very murky
as to how far open_namei() actually got, and whether or not that
mount write count was taken.  That makes it a bad interface.

All that the current do_filp_open() really does is allocate the
nameidata on the stack, then call open_namei().

So, this merges those two functions and moves filp_open() over
to namei.c so it can be close to its buddy: do_filp_open().  It
also gets a kerneldoc comment in the process.

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

2 files changed, 57 insertions, 62 deletions

diff --git a/fs/namei.c b/fs/namei.c
index c70dbf720109..a1f8bbbd58e5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1725,17 +1725,13 @@ static inline int open_to_namei_flags(int 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.  See open_to_namei_flags().
- * SMP-safe
  */
-int open_namei(int dfd, const char *pathname, int open_flag,
-                int mode, struct nameidata *nd)
+struct file *do_filp_open(int dfd, const char *pathname,
+                int open_flag, int mode)
 {
+        struct nameidata nd;
         int acc_mode, error;
         struct path path;
         struct dentry *dir;
@@ -1758,18 +1754,19 @@ int open_namei(int dfd, const char *pathname, int open_flag,
          */
         if (!(flag & O_CREAT)) {
                 error = path_lookup_open(dfd, pathname, lookup_flags(flag),
-                                         nd, flag);
+                                         &nd, flag);
                 if (error)
-                        return error;
+                        return ERR_PTR(error);
                 goto ok;
         }
 
         /*
          * Create - we need to know the parent.
          */
-        error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode);
+        error = path_lookup_create(dfd, pathname, LOOKUP_PARENT,
+                                   &nd, flag, mode);
         if (error)
-                return error;
+                return ERR_PTR(error);
 
         /*
          * We have the parent and last component. First of all, check
@@ -1777,14 +1774,14 @@ int open_namei(int dfd, const char *pathname, int open_flag,
          * will not do.
          */
         error = -EISDIR;
-        if (nd->last_type != LAST_NORM || nd->last.name[nd->last.len])
+        if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len])
                 goto exit;
 
-        dir = nd->path.dentry;
-        nd->flags &= ~LOOKUP_PARENT;
+        dir = nd.path.dentry;
+        nd.flags &= ~LOOKUP_PARENT;
         mutex_lock(&dir->d_inode->i_mutex);
-        path.dentry = lookup_hash(nd);
-        path.mnt = nd->path.mnt;
+        path.dentry = lookup_hash(&nd);
+        path.mnt = nd.path.mnt;
 
 do_last:
         error = PTR_ERR(path.dentry);
@@ -1793,18 +1790,18 @@ do_last:
                 goto exit;
         }
 
-        if (IS_ERR(nd->intent.open.file)) {
+        if (IS_ERR(nd.intent.open.file)) {
                 mutex_unlock(&dir->d_inode->i_mutex);
-                error = PTR_ERR(nd->intent.open.file);
+                error = PTR_ERR(nd.intent.open.file);
                 goto exit_dput;
         }
 
         /* 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;
+                return nameidata_to_filp(&nd, open_flag);
         }
 
         /*
@@ -1829,23 +1826,23 @@ do_last:
         if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
                 goto do_link;
 
-        path_to_nameidata(&path, nd);
+        path_to_nameidata(&path, &nd);
         error = -EISDIR;
         if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
                 goto exit;
 ok:
-        error = may_open(nd, acc_mode, flag);
+        error = may_open(&nd, acc_mode, flag);
         if (error)
                 goto exit;
-        return 0;
+        return nameidata_to_filp(&nd, open_flag);
 
 exit_dput:
-        path_put_conditional(&path, nd);
+        path_put_conditional(&path, &nd);
 exit:
-        if (!IS_ERR(nd->intent.open.file))
-                release_open_intent(nd);
-        path_put(&nd->path);
-        return error;
+        if (!IS_ERR(nd.intent.open.file))
+                release_open_intent(&nd);
+        path_put(&nd.path);
+        return ERR_PTR(error);
 
 do_link:
         error = -ELOOP;
@@ -1861,43 +1858,60 @@ do_link:
          * stored in nd->last.name and we will have to putname() it when we
          * are done. Procfs-like symlinks just set LAST_BIND.
          */
-        nd->flags |= LOOKUP_PARENT;
-        error = security_inode_follow_link(path.dentry, nd);
+        nd.flags |= LOOKUP_PARENT;
+        error = security_inode_follow_link(path.dentry, &nd);
         if (error)
                 goto exit_dput;
-        error = __do_follow_link(&path, nd);
+        error = __do_follow_link(&path, &nd);
         if (error) {
                 /* Does someone understand code flow here? Or it is only
                  * me so stupid? Anathema to whoever designed this non-sense
                  * with "intent.open".
                  */
-                release_open_intent(nd);
-                return error;
+                release_open_intent(&nd);
+                return ERR_PTR(error);
         }
-        nd->flags &= ~LOOKUP_PARENT;
-        if (nd->last_type == LAST_BIND)
+        nd.flags &= ~LOOKUP_PARENT;
+        if (nd.last_type == LAST_BIND)
                 goto ok;
         error = -EISDIR;
-        if (nd->last_type != LAST_NORM)
+        if (nd.last_type != LAST_NORM)
                 goto exit;
-        if (nd->last.name[nd->last.len]) {
-                __putname(nd->last.name);
+        if (nd.last.name[nd.last.len]) {
+                __putname(nd.last.name);
                 goto exit;
         }
         error = -ELOOP;
         if (count++==32) {
-                __putname(nd->last.name);
+                __putname(nd.last.name);
                 goto exit;
         }
-        dir = nd->path.dentry;
+        dir = nd.path.dentry;
         mutex_lock(&dir->d_inode->i_mutex);
-        path.dentry = lookup_hash(nd);
-        path.mnt = nd->path.mnt;
-        __putname(nd->last.name);
+        path.dentry = lookup_hash(&nd);
+        path.mnt = nd.path.mnt;
+        __putname(nd.last.name);
         goto do_last;
 }
 
 /**
+ * filp_open - open file and return file pointer
+ *
+ * @filename:   path to open
+ * @flags:      open flags as per the open(2) second argument
+ * @mode:       mode for the new file if O_CREAT is set, else ignored
+ *
+ * This is the helper to open a file from kernelspace if you really
+ * have to.  But in generally you should not do this, so please move
+ * along, nothing to see here..
+ */
+struct file *filp_open(const char *filename, int flags, int mode)
+{
+        return do_filp_open(AT_FDCWD, filename, flags, mode);
+}
+EXPORT_SYMBOL(filp_open);
+
+/**
  * lookup_create - lookup a dentry, creating it if it doesn't exist
  * @nd: nameidata info
  * @is_dir: directory flag
diff --git a/fs/open.c b/fs/open.c
index 5ab3f3f079c0..8111947905d8 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -796,25 +796,6 @@ cleanup_file:
         return ERR_PTR(error);
 }
 
-static struct file *do_filp_open(int dfd, const char *filename, int flags,
-                                 int mode)
-{
-        int error;
-        struct nameidata nd;
-
-        error = open_namei(dfd, filename, flags, mode, &nd);
-        if (!error)
-                return nameidata_to_filp(&nd, flags);
-
-        return ERR_PTR(error);
-}
-
-struct file *filp_open(const char *filename, int flags, int mode)
-{
-        return do_filp_open(AT_FDCWD, filename, flags, mode);
-}
-EXPORT_SYMBOL(filp_open);
-
 /**
  * lookup_instantiate_filp - instantiates the open intent filp
  * @nd: pointer to nameidata