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Subject[PATCH 01/20] prepare for write access checks: collapse if()
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Date

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>
---
lxc-dave/fs/namei.c | 93 +++++++++++++++++++++++++++-------------------------
lxc-dave/fs/open.c | 22 +++++++-----
2 files changed, 64 insertions(+), 51 deletions(-)
diff -puN fs/namei.c~C-prepwork-collapse-ifs fs/namei.c
--- lxc/fs/namei.c~C-prepwork-collapse-ifs 2006-06-27 10:40:24.000000000 -0700
+++ lxc-dave/fs/namei.c 2006-06-27 10:40:24.000000000 -0700
@@ -1911,30 +1911,32 @@ asmlinkage long sys_mkdirat(int dfd, con
{
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;
}

@@ -2033,10 +2035,11 @@ static long do_rmdir(int dfd, const char
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);
@@ -2176,30 +2179,33 @@ asmlinkage long sys_symlinkat(const char
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;
}
@@ -2285,10 +2291,11 @@ asmlinkage long sys_linkat(int olddfd, c
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 -puN fs/open.c~C-prepwork-collapse-ifs fs/open.c
--- lxc/fs/open.c~C-prepwork-collapse-ifs 2006-06-27 10:40:24.000000000 -0700
+++ lxc-dave/fs/open.c 2006-06-27 10:40:24.000000000 -0700
@@ -520,15 +520,21 @@ asmlinkage long sys_faccessat(int dfd, c
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;
_
-
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