Make ->d_sb assign-once and always non-NULL
New helper (non-exported, fs/internal.h-only): __d_alloc(sb, name).
Allocates dentry, sets its ->d_sb to given superblock and sets
->d_op accordingly. Old d_alloc(NULL, name) callers are converted
to that (all of them know what superblock they want). d_alloc()
itself is left only for parent != NULl case; uses __d_alloc(),
inserts result into the list of parent's children.
Note that now ->d_sb is assign-once and never NULL *and*
->d_parent is never NULL either.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/dcache.c b/fs/dcache.c
index d390213..c61edd0 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1275,8 +1275,8 @@
};
/**
- * d_alloc - allocate a dcache entry
- * @parent: parent of entry to allocate
+ * __d_alloc - allocate a dcache entry
+ * @sb: filesystem it will belong to
* @name: qstr of the name
*
* Allocates a dentry. It returns %NULL if there is insufficient memory
@@ -1284,7 +1284,7 @@
* copied and the copy passed in may be reused after this call.
*/
-struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
+struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
{
struct dentry *dentry;
char *dname;
@@ -1314,8 +1314,8 @@
spin_lock_init(&dentry->d_lock);
seqcount_init(&dentry->d_seq);
dentry->d_inode = NULL;
- dentry->d_parent = NULL;
- dentry->d_sb = NULL;
+ dentry->d_parent = dentry;
+ dentry->d_sb = sb;
dentry->d_op = NULL;
dentry->d_fsdata = NULL;
INIT_HLIST_BL_NODE(&dentry->d_hash);
@@ -1323,36 +1323,47 @@
INIT_LIST_HEAD(&dentry->d_subdirs);
INIT_LIST_HEAD(&dentry->d_alias);
INIT_LIST_HEAD(&dentry->d_u.d_child);
-
- if (parent) {
- spin_lock(&parent->d_lock);
- /*
- * don't need child lock because it is not subject
- * to concurrency here
- */
- __dget_dlock(parent);
- dentry->d_parent = parent;
- dentry->d_sb = parent->d_sb;
- d_set_d_op(dentry, dentry->d_sb->s_d_op);
- list_add(&dentry->d_u.d_child, &parent->d_subdirs);
- spin_unlock(&parent->d_lock);
- }
+ d_set_d_op(dentry, dentry->d_sb->s_d_op);
this_cpu_inc(nr_dentry);
return dentry;
}
+
+/**
+ * d_alloc - allocate a dcache entry
+ * @parent: parent of entry to allocate
+ * @name: qstr of the name
+ *
+ * Allocates a dentry. It returns %NULL if there is insufficient memory
+ * available. On a success the dentry is returned. The name passed in is
+ * copied and the copy passed in may be reused after this call.
+ */
+struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
+{
+ struct dentry *dentry = __d_alloc(parent->d_sb, name);
+ if (!dentry)
+ return NULL;
+
+ spin_lock(&parent->d_lock);
+ /*
+ * don't need child lock because it is not subject
+ * to concurrency here
+ */
+ __dget_dlock(parent);
+ dentry->d_parent = parent;
+ list_add(&dentry->d_u.d_child, &parent->d_subdirs);
+ spin_unlock(&parent->d_lock);
+
+ return dentry;
+}
EXPORT_SYMBOL(d_alloc);
struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
{
- struct dentry *dentry = d_alloc(NULL, name);
- if (dentry) {
- dentry->d_sb = sb;
- d_set_d_op(dentry, dentry->d_sb->s_d_op);
- dentry->d_parent = dentry;
+ struct dentry *dentry = __d_alloc(sb, name);
+ if (dentry)
dentry->d_flags |= DCACHE_DISCONNECTED;
- }
return dentry;
}
EXPORT_SYMBOL(d_alloc_pseudo);
@@ -1522,13 +1533,9 @@
if (root_inode) {
static const struct qstr name = { .name = "/", .len = 1 };
- res = d_alloc(NULL, &name);
- if (res) {
- res->d_sb = root_inode->i_sb;
- d_set_d_op(res, res->d_sb->s_d_op);
- res->d_parent = res;
+ res = __d_alloc(root_inode->i_sb, &name);
+ if (res)
d_instantiate(res, root_inode);
- }
}
return res;
}
@@ -1589,13 +1596,11 @@
if (res)
goto out_iput;
- tmp = d_alloc(NULL, &anonstring);
+ tmp = __d_alloc(inode->i_sb, &anonstring);
if (!tmp) {
res = ERR_PTR(-ENOMEM);
goto out_iput;
}
- tmp->d_parent = tmp; /* make sure dput doesn't croak */
-
spin_lock(&inode->i_lock);
res = __d_find_any_alias(inode);
@@ -1607,8 +1612,6 @@
/* attach a disconnected dentry */
spin_lock(&tmp->d_lock);
- tmp->d_sb = inode->i_sb;
- d_set_d_op(tmp, tmp->d_sb->s_d_op);
tmp->d_inode = inode;
tmp->d_flags |= DCACHE_DISCONNECTED;
list_add(&tmp->d_alias, &inode->i_dentry);