[PATCH] r/o bind mounts: prepare for write access checks: collapse if()

We're shortly going to be adding a bunch more permission checks in these
functions.  That requires adding either a bunch of new if() conditions, or
some gotos.  This patch collapses existing if()s and uses gotos instead to
prepare for the upcoming changes.

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

2 files changed, 87 insertions, 70 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 2892e68d3a86..7bdceedd254c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1934,30 +1934,32 @@ asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
 {
         int error = 0;
         char * tmp;
+        struct dentry *dentry;
+        struct nameidata nd;
 
         tmp = getname(pathname);
         error = PTR_ERR(tmp);
-        if (!IS_ERR(tmp)) {
-                struct dentry *dentry;
-                struct nameidata nd;
+        if (IS_ERR(tmp))
+                goto out_err;
 
-                error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
-                if (error)
-                        goto out;
-                dentry = lookup_create(&nd, 1);
-                error = PTR_ERR(dentry);
-                if (!IS_ERR(dentry)) {
-                        if (!IS_POSIXACL(nd.dentry->d_inode))
-                                mode &= ~current->fs->umask;
-                        error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
-                        dput(dentry);
-                }
-                mutex_unlock(&nd.dentry->d_inode->i_mutex);
-                path_release(&nd);
-out:
-                putname(tmp);
-        }
+        error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
+        if (error)
+                goto out;
+        dentry = lookup_create(&nd, 1);
+        error = PTR_ERR(dentry);
+        if (IS_ERR(dentry))
+                goto out_unlock;
 
+        if (!IS_POSIXACL(nd.dentry->d_inode))
+                mode &= ~current->fs->umask;
+        error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
+        dput(dentry);
+out_unlock:
+        mutex_unlock(&nd.dentry->d_inode->i_mutex);
+        path_release(&nd);
+out:
+        putname(tmp);
+out_err:
         return error;
 }
 
@@ -2056,10 +2058,11 @@ static long do_rmdir(int dfd, const char __user *pathname)
         mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
         dentry = lookup_hash(&nd);
         error = PTR_ERR(dentry);
-        if (!IS_ERR(dentry)) {
-                error = vfs_rmdir(nd.dentry->d_inode, dentry);
-                dput(dentry);
-        }
+        if (IS_ERR(dentry))
+                goto exit2;
+        error = vfs_rmdir(nd.dentry->d_inode, dentry);
+        dput(dentry);
+exit2:
         mutex_unlock(&nd.dentry->d_inode->i_mutex);
 exit1:
         path_release(&nd);
@@ -2199,30 +2202,33 @@ asmlinkage long sys_symlinkat(const char __user *oldname,
         int error = 0;
         char * from;
         char * to;
+        struct dentry *dentry;
+        struct nameidata nd;
 
         from = getname(oldname);
         if(IS_ERR(from))
                 return PTR_ERR(from);
         to = getname(newname);
         error = PTR_ERR(to);
-        if (!IS_ERR(to)) {
-                struct dentry *dentry;
-                struct nameidata nd;
+        if (IS_ERR(to))
+                goto out_putname;
 
-                error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
-                if (error)
-                        goto out;
-                dentry = lookup_create(&nd, 0);
-                error = PTR_ERR(dentry);
-                if (!IS_ERR(dentry)) {
-                        error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
-                        dput(dentry);
-                }
-                mutex_unlock(&nd.dentry->d_inode->i_mutex);
-                path_release(&nd);
+        error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
+        if (error)
+                goto out;
+        dentry = lookup_create(&nd, 0);
+        error = PTR_ERR(dentry);
+        if (IS_ERR(dentry))
+                goto out_unlock;
+
+        error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
+        dput(dentry);
+out_unlock:
+        mutex_unlock(&nd.dentry->d_inode->i_mutex);
+        path_release(&nd);
 out:
-                putname(to);
-        }
+        putname(to);
+out_putname:
         putname(from);
         return error;
 }
@@ -2308,10 +2314,11 @@ asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
                 goto out_release;
         new_dentry = lookup_create(&nd, 0);
         error = PTR_ERR(new_dentry);
-        if (!IS_ERR(new_dentry)) {
-                error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
-                dput(new_dentry);
-        }
+        if (IS_ERR(new_dentry))
+                goto out_unlock;
+        error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
+        dput(new_dentry);
+out_unlock:
         mutex_unlock(&nd.dentry->d_inode->i_mutex);
 out_release:
         path_release(&nd);
diff --git a/fs/open.c b/fs/open.c
index 35c3e454458e..89e0c237a636 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -386,15 +386,21 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
                 current->cap_effective = current->cap_permitted;
 
         res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
-        if (!res) {
-                res = vfs_permission(&nd, mode);
-                /* SuS v2 requires we report a read only fs too */
-                if(!res && (mode & S_IWOTH) && IS_RDONLY(nd.dentry->d_inode)
-                   && !special_file(nd.dentry->d_inode->i_mode))
-                        res = -EROFS;
-                path_release(&nd);
-        }
+        if (res)
+                goto out;
+
+        res = vfs_permission(&nd, mode);
+        /* SuS v2 requires we report a read only fs too */
+        if(res || !(mode & S_IWOTH) ||
+           special_file(nd.dentry->d_inode->i_mode))
+                goto out_path_release;
+
+        if(IS_RDONLY(nd.dentry->d_inode))
+                res = -EROFS;
 
+out_path_release:
+        path_release(&nd);
+out:
         current->fsuid = old_fsuid;
         current->fsgid = old_fsgid;
         current->cap_effective = old_cap;
@@ -603,10 +609,11 @@ asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
         int error;
 
         error = user_path_walk(filename, &nd);
-        if (!error) {
-                error = chown_common(nd.dentry, user, group);
-                path_release(&nd);
-        }
+        if (error)
+                goto out;
+        error = chown_common(nd.dentry, user, group);
+        path_release(&nd);
+out:
         return error;
 }
 
@@ -622,10 +629,10 @@ asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user,
 
         follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
         error = __user_walk_fd(dfd, filename, follow, &nd);
-        if (!error) {
-                error = chown_common(nd.dentry, user, group);
-                path_release(&nd);
-        }
+        if (error)
+                goto out;
+        error = chown_common(nd.dentry, user, group);
+        path_release(&nd);
 out:
         return error;
 }
@@ -636,10 +643,11 @@ asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group
         int error;
 
         error = user_path_walk_link(filename, &nd);
-        if (!error) {
-                error = chown_common(nd.dentry, user, group);
-                path_release(&nd);
-        }
+        if (error)
+                goto out;
+        error = chown_common(nd.dentry, user, group);
+        path_release(&nd);
+out:
         return error;
 }
 
@@ -648,15 +656,17 @@ asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
 {
         struct file * file;
         int error = -EBADF;
+        struct dentry * dentry;
 
         file = fget(fd);
-        if (file) {
-                struct dentry * dentry;
-                dentry = file->f_dentry;
-                audit_inode(NULL, dentry->d_inode);
-                error = chown_common(dentry, user, group);
-                fput(file);
-        }
+        if (!file)
+                goto out;
+
+        dentry = file->f_dentry;
+        audit_inode(NULL, dentry->d_inode);
+        error = chown_common(dentry, user, group);
+        fput(file);
+out:
         return error;
 }