fs: dcache reduce branches in lookup path
Reduce some branches and memory accesses in dcache lookup by adding dentry
flags to indicate common d_ops are set, rather than having to check them.
This saves a pointer memory access (dentry->d_op) in common path lookup
situations, and saves another pointer load and branch in cases where we
have d_op but not the particular operation.
Patched with:
git grep -E '[.>]([[:space:]])*d_op([[:space:]])*=' | xargs sed -e 's/\([^\t ]*\)->d_op = \(.*\);/d_set_d_op(\1, \2);/' -e 's/\([^\t ]*\)\.d_op = \(.*\);/d_set_d_op(\&\1, \2);/' -i
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
diff --git a/fs/dcache.c b/fs/dcache.c
index 1d5cf51..f9693da 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -398,7 +398,7 @@
return;
}
- if (dentry->d_op && dentry->d_op->d_delete) {
+ if (dentry->d_flags & DCACHE_OP_DELETE) {
if (dentry->d_op->d_delete(dentry))
goto kill_it;
}
@@ -1301,6 +1301,28 @@
}
EXPORT_SYMBOL(d_alloc_name);
+void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
+{
+ BUG_ON(dentry->d_op);
+ BUG_ON(dentry->d_flags & (DCACHE_OP_HASH |
+ DCACHE_OP_COMPARE |
+ DCACHE_OP_REVALIDATE |
+ DCACHE_OP_DELETE ));
+ dentry->d_op = op;
+ if (!op)
+ return;
+ if (op->d_hash)
+ dentry->d_flags |= DCACHE_OP_HASH;
+ if (op->d_compare)
+ dentry->d_flags |= DCACHE_OP_COMPARE;
+ if (op->d_revalidate)
+ dentry->d_flags |= DCACHE_OP_REVALIDATE;
+ if (op->d_delete)
+ dentry->d_flags |= DCACHE_OP_DELETE;
+
+}
+EXPORT_SYMBOL(d_set_d_op);
+
static void __d_instantiate(struct dentry *dentry, struct inode *inode)
{
spin_lock(&dentry->d_lock);
@@ -1731,7 +1753,7 @@
*/
if (read_seqcount_retry(&dentry->d_seq, *seq))
goto seqretry;
- if (parent->d_op && parent->d_op->d_compare) {
+ if (parent->d_flags & DCACHE_OP_COMPARE) {
if (parent->d_op->d_compare(parent, *inode,
dentry, i,
tlen, tname, name))
@@ -1846,7 +1868,7 @@
*/
tlen = dentry->d_name.len;
tname = dentry->d_name.name;
- if (parent->d_op && parent->d_op->d_compare) {
+ if (parent->d_flags & DCACHE_OP_COMPARE) {
if (parent->d_op->d_compare(parent, parent->d_inode,
dentry, dentry->d_inode,
tlen, tname, name))
@@ -1887,7 +1909,7 @@
* routine may choose to leave the hash value unchanged.
*/
name->hash = full_name_hash(name->name, name->len);
- if (dir->d_op && dir->d_op->d_hash) {
+ if (dir->d_flags & DCACHE_OP_HASH) {
if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0)
goto out;
}