vfs: trivial __d_lookup_rcu() cleanups
These don't change any semantics, but they clean up the code a bit and
mark some arguments appropriately 'const'.
They came up as I was doing the word-at-a-time dcache name accessor
code, and cleaning this up now allows me to send out a smaller relevant
interesting patch for the experimental stuff.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/dcache.c b/fs/dcache.c
index fe19ac1..138be96 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -104,7 +104,7 @@
static struct hlist_bl_head *dentry_hashtable __read_mostly;
-static inline struct hlist_bl_head *d_hash(struct dentry *parent,
+static inline struct hlist_bl_head *d_hash(const struct dentry *parent,
unsigned long hash)
{
hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
@@ -1717,8 +1717,9 @@
* child is looked up. Thus, an interlocking stepping of sequence lock checks
* is formed, giving integrity down the path walk.
*/
-struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
- unsigned *seq, struct inode **inode)
+struct dentry *__d_lookup_rcu(const struct dentry *parent,
+ const struct qstr *name,
+ unsigned *seqp, struct inode **inode)
{
unsigned int len = name->len;
unsigned int hash = name->hash;
@@ -1748,6 +1749,7 @@
* See Documentation/filesystems/path-lookup.txt for more details.
*/
hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
+ unsigned seq;
struct inode *i;
const char *tname;
int tlen;
@@ -1756,7 +1758,7 @@
continue;
seqretry:
- *seq = read_seqcount_begin(&dentry->d_seq);
+ seq = read_seqcount_begin(&dentry->d_seq);
if (dentry->d_parent != parent)
continue;
if (d_unhashed(dentry))
@@ -1771,7 +1773,7 @@
* edge of memory when walking. If we could load this
* atomically some other way, we could drop this check.
*/
- if (read_seqcount_retry(&dentry->d_seq, *seq))
+ if (read_seqcount_retry(&dentry->d_seq, seq))
goto seqretry;
if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
if (parent->d_op->d_compare(parent, *inode,
@@ -1788,6 +1790,7 @@
* order to do anything useful with the returned dentry
* anyway.
*/
+ *seqp = seq;
*inode = i;
return dentry;
}