gut do_filp_open() a bit more (do_last separation)

Brute-force separation of stuff reachable from do_last: with
the exception of do_link:; just take all that crap to a helper
function as-is and have it tell the caller if it has to go
to do_link.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 103 insertions, 68 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 60b74b3946a1..3c39fa1608c5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1645,6 +1645,104 @@ exit:
         return ERR_PTR(error);
 }
 
+static struct file *do_last(struct nameidata *nd, struct path *path,
+                            int open_flag, int flag, int acc_mode,
+                            int mode, const char *pathname,
+                            struct dentry *dir, int *is_link)
+{
+        struct file *filp;
+        int error;
+
+        *is_link = 0;
+
+        error = PTR_ERR(path->dentry);
+        if (IS_ERR(path->dentry)) {
+                mutex_unlock(&dir->d_inode->i_mutex);
+                goto exit;
+        }
+
+        if (IS_ERR(nd->intent.open.file)) {
+                error = PTR_ERR(nd->intent.open.file);
+                goto exit_mutex_unlock;
+        }
+
+        /* Negative dentry, just create the file */
+        if (!path->dentry->d_inode) {
+                /*
+                 * This write is needed to ensure that a
+                 * ro->rw transition does not occur between
+                 * the time when the file is created and when
+                 * a permanent write count is taken through
+                 * the 'struct file' in nameidata_to_filp().
+                 */
+                error = mnt_want_write(nd->path.mnt);
+                if (error)
+                        goto exit_mutex_unlock;
+                error = __open_namei_create(nd, path, open_flag, mode);
+                if (error) {
+                        mnt_drop_write(nd->path.mnt);
+                        goto exit;
+                }
+                filp = nameidata_to_filp(nd);
+                mnt_drop_write(nd->path.mnt);
+                if (nd->root.mnt)
+                        path_put(&nd->root);
+                if (!IS_ERR(filp)) {
+                        error = ima_file_check(filp, acc_mode);
+                        if (error) {
+                                fput(filp);
+                                filp = ERR_PTR(error);
+                        }
+                }
+                return filp;
+        }
+
+        /*
+         * It already exists.
+         */
+        mutex_unlock(&dir->d_inode->i_mutex);
+        audit_inode(pathname, path->dentry);
+
+        error = -EEXIST;
+        if (flag & O_EXCL)
+                goto exit_dput;
+
+        if (__follow_mount(path)) {
+                error = -ELOOP;
+                if (flag & O_NOFOLLOW)
+                        goto exit_dput;
+        }
+
+        error = -ENOENT;
+        if (!path->dentry->d_inode)
+                goto exit_dput;
+        if (path->dentry->d_inode->i_op->follow_link) {
+                *is_link = 1;
+                return NULL;
+        }
+
+        path_to_nameidata(path, nd);
+        error = -EISDIR;
+        if (S_ISDIR(path->dentry->d_inode->i_mode))
+                goto exit;
+        filp = finish_open(nd, open_flag, flag, acc_mode);
+        if (nd->root.mnt)
+                path_put(&nd->root);
+        return filp;
+
+exit_mutex_unlock:
+        mutex_unlock(&dir->d_inode->i_mutex);
+exit_dput:
+        path_put_conditional(path, nd);
+exit:
+        if (!IS_ERR(nd->intent.open.file))
+                release_open_intent(nd);
+        if (nd->root.mnt)
+                path_put(&nd->root);
+        path_put(&nd->path);
+        return ERR_PTR(error);
+}
+
 /*
  * Note that the low bits of the passed in "open_flag"
  * are not the same as in the local variable "flag". See
@@ -1661,6 +1759,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
         int count = 0;
         int flag = open_to_namei_flags(open_flag);
         int force_reval = 0;
+        int is_link;
 
         /*
          * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
@@ -1754,82 +1853,18 @@ reval:
         path.mnt = nd.path.mnt;
 
 do_last:
-        error = PTR_ERR(path.dentry);
-        if (IS_ERR(path.dentry)) {
-                mutex_unlock(&dir->d_inode->i_mutex);
-                goto exit;
-        }
-
-        if (IS_ERR(nd.intent.open.file)) {
-                error = PTR_ERR(nd.intent.open.file);
-                goto exit_mutex_unlock;
-        }
-
-        /* Negative dentry, just create the file */
-        if (!path.dentry->d_inode) {
-                /*
-                 * This write is needed to ensure that a
-                 * ro->rw transition does not occur between
-                 * the time when the file is created and when
-                 * a permanent write count is taken through
-                 * the 'struct file' in nameidata_to_filp().
-                 */
-                error = mnt_want_write(nd.path.mnt);
-                if (error)
-                        goto exit_mutex_unlock;
-                error = __open_namei_create(&nd, &path, open_flag, mode);
-                if (error) {
-                        mnt_drop_write(nd.path.mnt);
-                        goto exit;
-                }
-                filp = nameidata_to_filp(&nd);
-                mnt_drop_write(nd.path.mnt);
-                if (nd.root.mnt)
-                        path_put(&nd.root);
-                if (!IS_ERR(filp)) {
-                        error = ima_file_check(filp, acc_mode);
-                        if (error) {
-                                fput(filp);
-                                filp = ERR_PTR(error);
-                        }
-                }
-                return filp;
-        }
-
-        /*
-         * It already exists.
-         */
-        mutex_unlock(&dir->d_inode->i_mutex);
-        audit_inode(pathname, path.dentry);
-
-        error = -EEXIST;
-        if (flag & O_EXCL)
-                goto exit_dput;
-
-        if (__follow_mount(&path)) {
-                error = -ELOOP;
-                if (flag & O_NOFOLLOW)
-                        goto exit_dput;
-        }
-
-        error = -ENOENT;
-        if (!path.dentry->d_inode)
-                goto exit_dput;
-        if (path.dentry->d_inode->i_op->follow_link)
+        filp = do_last(&nd, &path, open_flag, flag, acc_mode, mode,
+                       pathname, dir, &is_link);
+        if (is_link)
                 goto do_link;
+        return filp;
 
-        path_to_nameidata(&path, &nd);
-        error = -EISDIR;
-        if (S_ISDIR(path.dentry->d_inode->i_mode))
-                goto exit;
 ok:
         filp = finish_open(&nd, open_flag, flag, acc_mode);
         if (nd.root.mnt)
                 path_put(&nd.root);
         return filp;
 
-exit_mutex_unlock:
-        mutex_unlock(&dir->d_inode->i_mutex);
 exit_dput:
         path_put_conditional(&path, &nd);
 exit: