ovl: consolidate lookup for underlying layers
Use a common helper for lookup of upper and lower layers. This paves the
way for looking up directory redirects.
No functional change.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 2e0b84c6..f213297 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -13,26 +13,13 @@
#include "overlayfs.h"
#include "ovl_entry.h"
-static struct dentry *ovl_lookup_real(struct dentry *dir,
- const struct qstr *name)
-{
- struct dentry *dentry;
-
- dentry = lookup_one_len_unlocked(name->name, dir, name->len);
- if (IS_ERR(dentry)) {
- if (PTR_ERR(dentry) == -ENOENT ||
- PTR_ERR(dentry) == -ENAMETOOLONG)
- dentry = NULL;
- } else if (!dentry->d_inode) {
- dput(dentry);
- dentry = NULL;
- } else if (ovl_dentry_weird(dentry)) {
- dput(dentry);
- /* Don't support traversing automounts and other weirdness */
- dentry = ERR_PTR(-EREMOTE);
- }
- return dentry;
-}
+struct ovl_lookup_data {
+ struct qstr name;
+ bool is_dir;
+ bool opaque;
+ bool stop;
+ bool last;
+};
static bool ovl_is_opaquedir(struct dentry *dentry)
{
@@ -49,6 +36,64 @@ static bool ovl_is_opaquedir(struct dentry *dentry)
return false;
}
+static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
+ const char *name, unsigned int namelen,
+ struct dentry **ret)
+{
+ struct dentry *this;
+ int err;
+
+ this = lookup_one_len_unlocked(name, base, namelen);
+ if (IS_ERR(this)) {
+ err = PTR_ERR(this);
+ this = NULL;
+ if (err == -ENOENT || err == -ENAMETOOLONG)
+ goto out;
+ goto out_err;
+ }
+ if (!this->d_inode)
+ goto put_and_out;
+
+ if (ovl_dentry_weird(this)) {
+ /* Don't support traversing automounts and other weirdness */
+ err = -EREMOTE;
+ goto out_err;
+ }
+ if (ovl_is_whiteout(this)) {
+ d->stop = d->opaque = true;
+ goto put_and_out;
+ }
+ if (!d_can_lookup(this)) {
+ d->stop = true;
+ if (d->is_dir)
+ goto put_and_out;
+ goto out;
+ }
+ d->is_dir = true;
+ if (!d->last && ovl_is_opaquedir(this)) {
+ d->stop = d->opaque = true;
+ goto out;
+ }
+out:
+ *ret = this;
+ return 0;
+
+put_and_out:
+ dput(this);
+ this = NULL;
+ goto out;
+
+out_err:
+ dput(this);
+ return err;
+}
+
+static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
+ struct dentry **ret)
+{
+ return ovl_lookup_single(base, d, d->name.name, d->name.len, ret);
+}
+
/*
* Returns next layer in stack starting from top.
* Returns -1 if this is the last layer.
@@ -82,11 +127,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int ctr = 0;
struct inode *inode = NULL;
bool upperopaque = false;
- bool stop = false;
- bool isdir = false;
struct dentry *this;
unsigned int i;
int err;
+ struct ovl_lookup_data d = {
+ .name = dentry->d_name,
+ .is_dir = false,
+ .opaque = false,
+ .stop = false,
+ .last = !poe->numlower,
+ };
if (dentry->d_name.len > ofs->namelen)
return ERR_PTR(-ENAMETOOLONG);
@@ -94,70 +144,36 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
old_cred = ovl_override_creds(dentry->d_sb);
upperdir = ovl_upperdentry_dereference(poe);
if (upperdir) {
- this = ovl_lookup_real(upperdir, &dentry->d_name);
- err = PTR_ERR(this);
- if (IS_ERR(this))
+ err = ovl_lookup_layer(upperdir, &d, &upperdentry);
+ if (err)
goto out;
- if (this) {
- if (unlikely(ovl_dentry_remote(this))) {
- dput(this);
- err = -EREMOTE;
- goto out;
- }
- if (ovl_is_whiteout(this)) {
- dput(this);
- this = NULL;
- stop = upperopaque = true;
- } else if (!d_is_dir(this)) {
- stop = true;
- } else {
- isdir = true;
- if (poe->numlower && ovl_is_opaquedir(this))
- stop = upperopaque = true;
- }
+ if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) {
+ dput(upperdentry);
+ err = -EREMOTE;
+ goto out;
}
- upperdentry = this;
+ upperopaque = d.opaque;
}
- if (!stop && poe->numlower) {
+ if (!d.stop && poe->numlower) {
err = -ENOMEM;
- stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
+ stack = kcalloc(poe->numlower, sizeof(struct path),
+ GFP_TEMPORARY);
if (!stack)
goto out_put_upper;
}
- for (i = 0; !stop && i < poe->numlower; i++) {
+ for (i = 0; !d.stop && i < poe->numlower; i++) {
struct path lowerpath = poe->lowerstack[i];
- this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
- err = PTR_ERR(this);
- if (IS_ERR(this))
+ d.last = i == poe->numlower - 1;
+ err = ovl_lookup_layer(lowerpath.dentry, &d, &this);
+ if (err)
goto out_put;
if (!this)
continue;
- if (ovl_is_whiteout(this)) {
- dput(this);
- break;
- }
- /*
- * If this is a non-directory then stop here.
- */
- if (!d_is_dir(this)) {
- if (isdir) {
- dput(this);
- break;
- }
- stop = true;
- } else {
- /*
- * Only makes sense to check opaque dir if this is not
- * the lowermost layer.
- */
- if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
- stop = true;
- }
stack[ctr].dentry = this;
stack[ctr].mnt = lowerpath.mnt;