Al Viro:
> That check is definitely bogus and I'm completely at loss as to WTF is it
> doing there. Thanks for catching that; this kind of idiotic braino can
> escape notice when rereading the code again and again, unfortunately ;-/
>
> Fixed, will push to Linus tonight or tomorrow.
Thank you too for fixing.
I've confirmed the patch was merged and it passed my local tests
too. Happy.
I have another and relatively less important suggestion. Since the two
groups tests in the loop are very similar, how about extract them as a
new single static function?
Do you think it will invite a performance down?
J. R. Okajima
diff --git a/fs/dcache.c b/fs/dcache.c
index 76afffd..3a9ebbc 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2462,14 +2462,42 @@ static void d_wait_lookup(struct dentry *dentry)
}
}
+/* tests for d_alloc_parallel() */
+static bool dap_test(struct dentry *dentry, const struct qstr *name,
+ struct dentry *parent, bool do_unhashed_test)
+{
+ bool ret;
+
+ ret = false;
+ if (dentry->d_name.hash != name->hash)
+ goto out;
+ if (dentry->d_parent != parent)
+ goto out;
+ if (do_unhashed_test && d_unhashed(dentry))
+ goto out;
+ if (parent->d_flags & DCACHE_OP_COMPARE) {
+ int tlen = dentry->d_name.len;
+ const char *tname = dentry->d_name.name;
+ if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
+ goto out;
+ } else {
+ unsigned int len = name->len;
+ if (dentry->d_name.len != len)
+ goto out;
+ if (dentry_cmp(dentry, name->name, len))
+ goto out;
+ }
+ ret = true;
+
+out:
+ return ret;
+}
+
struct dentry *d_alloc_parallel(struct dentry *parent,
const struct qstr *name,
wait_queue_head_t *wq)
{
- unsigned int len = name->len;
- unsigned int hash = name->hash;
- const unsigned char *str = name->name;
- struct hlist_bl_head *b = in_lookup_hash(parent, hash);
+ struct hlist_bl_head *b = in_lookup_hash(parent, name->hash);
struct hlist_bl_node *node;
struct dentry *new = d_alloc(parent, name);
struct dentry *dentry;
@@ -2515,21 +2543,8 @@ retry:
* we encounter.
*/
hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) {
- if (dentry->d_name.hash != hash)
- continue;
- if (dentry->d_parent != parent)
+ if (!dap_test(dentry, name, parent, /*do_unhashed_test*/false))
continue;
- if (parent->d_flags & DCACHE_OP_COMPARE) {
- int tlen = dentry->d_name.len;
- const char *tname = dentry->d_name.name;
- if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
- continue;
- } else {
- if (dentry->d_name.len != len)
- continue;
- if (dentry_cmp(dentry, str, len))
- continue;
- }
hlist_bl_unlock(b);
/* now we can try to grab a reference */
if (!lockref_get_not_dead(&dentry->d_lockref)) {
@@ -2550,23 +2565,9 @@ retry:
* d_lookup() would've found anyway. If it is, just return it;
* otherwise we really have to repeat the whole thing.
*/
- if (unlikely(dentry->d_name.hash != hash))
- goto mismatch;
- if (unlikely(dentry->d_parent != parent))
+ if (unlikely(!dap_test(dentry, name, parent,
+ /*do_unhashed_test*/true)))
goto mismatch;
- if (unlikely(d_unhashed(dentry)))
- goto mismatch;
- if (parent->d_flags & DCACHE_OP_COMPARE) {
- int tlen = dentry->d_name.len;
- const char *tname = dentry->d_name.name;
- if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
- goto mismatch;
- } else {
- if (unlikely(dentry->d_name.len != len))
- goto mismatch;
- if (unlikely(dentry_cmp(dentry, str, len)))
- goto mismatch;
- }
/* OK, it *is* a hashed match; return it */
spin_unlock(&dentry->d_lock);
dput(new);
--
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