[RFC] fs, proc: Introduce the /proc/<pid>/map_files/ directory v2
Tejun Heo
tj at kernel.org
Fri Aug 26 07:06:20 PDT 2011
Hello, Cyrill.
On Fri, Aug 26, 2011 at 05:16:20PM +0400, Cyrill Gorcunov wrote:
> Index: linux-2.6.git/fs/proc/base.c
> ===================================================================
> --- linux-2.6.git.orig/fs/proc/base.c
> +++ linux-2.6.git/fs/proc/base.c
> @@ -165,7 +165,7 @@ static int get_task_root(struct task_str
> return result;
> }
>
> -static int proc_cwd_link(struct inode *inode, struct path *path)
> +static int proc_cwd_link(struct dentry *dentry, struct inode *inode, struct path *path)
I don't think it's necessary to pass around both @dentry and @inode.
@inode can always be dereferenced from @dentry.
> +static int map_name_to_addr(const unsigned char *name, unsigned long *start, unsigned long *end)
> +{
> + int ret = -1;
Very minor but functions returning -1 for error bugs me a bit. Maybe
-EINVAL is better? Not a big deal either way.
> +static int map_files_d_revalidate(struct dentry *dentry, struct nameidata *nd)
> +{
...
> + if (vma) {
> + if (task_dumpable(task)) {
> + rcu_read_lock();
> + cred = __task_cred(task);
> + inode->i_uid = cred->euid;
> + inode->i_gid = cred->egid;
> + rcu_read_unlock();
> + } else {
> + inode->i_uid = 0;
> + inode->i_gid = 0;
> + }
> + security_task_to_inode(task, inode);
> + return 1;
Another minor point. Maybe it would be nice to factor this into a
function and share it w/ the fd one (and maybe sprinkle some comments
while at it too :)
> +struct map_files_info {
> + struct file *file;
> + unsigned char name[16+16+2]; /* max: %016lx-%016lx\0 */
> + unsigned long len;
> +};
That's slightly above 50 bytes.
> +static struct dentry *proc_map_files_lookup(struct inode *dir,
> + struct dentry *dentry, struct nameidata *nd)
> +{
> + unsigned long vm_start, vm_end;
> + struct task_struct *task;
> + struct vm_area_struct *vma;
> + struct mm_struct *mm;
> + struct dentry *result;
> +
> + result = ERR_PTR(-ENOENT);
> + task = get_proc_task(dir);
> + if (!task)
> + goto out_no_task;
> +
> + result = ERR_PTR(-EPERM);
> + if (!ptrace_may_access(task, PTRACE_MODE_READ));
> + goto out_no_mm;
> +
> + result = ERR_PTR(-ENOENT);
> + if (map_name_to_addr(dentry->d_name.name,
> + &vm_start, &vm_end))
> + goto out_no_mm;
Another nitpick: Maybe factor out the above three steps?
> +static int proc_map_files_readdir(struct file *filp, void *dirent, filldir_t filldir)
> +{
...
> + if (nr_files) {
> + info = kmalloc(nr_files * sizeof(*info), GFP_KERNEL);
I think we can just put this on stack.
All my comments are pretty cosmetic, so it generally looks good to me.
Andrew, what do you think?
Thanks.
--
tejun
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