On 01/26, Oleg Nesterov wrote:
>
> Al, Denys, unless I am totally confused the "restart" logic is very broken.
> We can't simply restart because the main loop changes dentry?
Plus prepend_name() can't actually return -ENAMETOOLONG,
"int error" inside the loop is wrong.
I believe the minimal fix is something like below. I'll try to test
this change (currently I can't) later and resend. And I still think
it can be cleanuped a bit, but this is minor.
Oleg.
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3103,7 +3103,7 @@ char *simple_dname(struct dentry *dentry, char *buffer,
int buflen)
/* these dentries are never renamed, so d_lock is not needed */
if (prepend(&end, &buflen, " (deleted)", 11) ||
prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) ||
- prepend(&end, &buflen, "/", 1))
+ prepend(&end, &buflen, "/", 1))
end = ERR_PTR(-ENAMETOOLONG);
return end;
}
@@ -3113,32 +3113,34 @@ char *simple_dname(struct dentry *dentry, char *buffer,
int buflen)
*/
static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
{
+ struct dentry *de;
char *end, *retval;
int len, seq = 0;
int error = 0;
+ if (buflen < 2)
+ goto Elong;
+
rcu_read_lock();
restart:
end = buf + buflen;
len = buflen;
prepend(&end, &len, "\0", 1);
- if (buflen < 1)
- goto Elong;
/* Get '/' right */
retval = end-1;
*retval = '/';
+ de = dentry;
read_seqbegin_or_lock(&rename_lock, &seq);
- while (!IS_ROOT(dentry)) {
- struct dentry *parent = dentry->d_parent;
- int error;
+ while (!IS_ROOT(de)) {
+ struct dentry *parent = de->d_parent;
prefetch(parent);
- error = prepend_name(&end, &len, &dentry->d_name);
+ error = prepend_name(&end, &len, &de->d_name);
if (error)
break;
retval = end;
- dentry = parent;
+ de = parent;
}
if (!(seq & 1))
rcu_read_unlock();
--
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