[RFC PATCH v3 2/9] ovl: Suppress negative dentry in lookup

[Chengguang Xu <cgxu519@mykernel.net>]

In order to reduce useless negative dentries in upper/lower
layers, specify LOOKUP_DONTCACHE_NEGATIVE flag in lookup
so that we can drop negative dentries which generated in
slow path of lookup.

Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
---
 fs/overlayfs/namei.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 0db23baf98e7..a400a7d126bd 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -200,7 +200,8 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
 	int err;
 	bool last_element = !post[0];
 
-	this = lookup_positive_unlocked(name, base, namelen);
+	this = lookup_positive_unlocked(name, base, namelen,
+					LOOKUP_DONTCACHE_NEGATIVE);
 	if (IS_ERR(this)) {
 		err = PTR_ERR(this);
 		this = NULL;
@@ -657,7 +658,7 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
 	if (err)
 		return ERR_PTR(err);
 
-	index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
+	index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len, 0);
 	kfree(name.name);
 	if (IS_ERR(index)) {
 		if (PTR_ERR(index) == -ENOENT)
@@ -689,7 +690,7 @@ struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
 	if (err)
 		return ERR_PTR(err);
 
-	index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
+	index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len, 0);
 	if (IS_ERR(index)) {
 		err = PTR_ERR(index);
 		if (err == -ENOENT) {
@@ -1137,7 +1138,7 @@ bool ovl_lower_positive(struct dentry *dentry)
 		struct dentry *lowerdir = poe->lowerstack[i].dentry;
 
 		this = lookup_positive_unlocked(name->name, lowerdir,
-					       name->len);
+					       name->len, 0);
 		if (IS_ERR(this)) {
 			switch (PTR_ERR(this)) {
 			case -ENOENT:
-- 
2.20.1