On Thu, May 17, 2018 at 10:10:58AM +0200, Miklos Szeredi wrote:
>
> Not the only reason: we don't want inode allocation to fail after
> successful creation. Solution: add a preallocated inode argument to
> ovl_get_inode() and deal with allocation failure there.
Here's a patch to split a helper out of iget5_locked() that takes a preallocated
inode. It makes the whole thing more readable, IMO, regardless of overlayfs's
needs.
Thanks,
Miklos
---
diff --git a/fs/inode.c b/fs/inode.c
index 13ceb98c3bd3..bb79e3f96147 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1002,6 +1002,52 @@ void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
}
EXPORT_SYMBOL(unlock_two_nondirectories);
+struct inode *iget5_prealloc(struct inode *inode,
+ struct super_block *sb, unsigned long hashval,
+ int (*test)(struct inode *, void *),
+ int (*set)(struct inode *, void *), void *data)
+{
+ struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+ struct inode *old;
+
+again:
+ spin_lock(&inode_hash_lock);
+ old = find_inode(sb, head, test, data);
+ if (unlikely(old)) {
+ /*
+ * Uhhuh, somebody else created the same inode under us.
+ * Use the old inode instead of the preallocated one.
+ */
+ spin_unlock(&inode_hash_lock);
+ wait_on_inode(old);
+ if (unlikely(inode_unhashed(old))) {
+ iput(old);
+ goto again;
+ }
+ return old;
+ }
+
+ if (unlikely(set(inode, data))) {
+ inode = NULL;
+ goto unlock;
+ }
+
+ /*
+ * Return the locked inode with I_NEW set, the
+ * caller is responsible for filling in the contents
+ */
+ spin_lock(&inode->i_lock);
+ inode->i_state = I_NEW;
+ hlist_add_head(&inode->i_hash, head);
+ spin_unlock(&inode->i_lock);
+ inode_sb_list_add(inode);
+unlock:
+ spin_unlock(&inode_hash_lock);
+
+ return inode;
+}
+EXPORT_SYMBOL(iget5_prealloc);
+
/**
* iget5_locked - obtain an inode from a mounted file system
* @sb: super block of file system
@@ -1026,66 +1072,18 @@ struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *),
int (*set)(struct inode *, void *), void *data)
{
- struct hlist_head *head = inode_hashtable + hash(sb, hashval);
- struct inode *inode;
-again:
- spin_lock(&inode_hash_lock);
- inode = find_inode(sb, head, test, data);
- spin_unlock(&inode_hash_lock);
+ struct inode *inode = ilookup5(sb, hashval, test, data);
- if (inode) {
- wait_on_inode(inode);
- if (unlikely(inode_unhashed(inode))) {
- iput(inode);
- goto again;
- }
- return inode;
- }
-
- inode = alloc_inode(sb);
- if (inode) {
- struct inode *old;
-
- spin_lock(&inode_hash_lock);
- /* We released the lock, so.. */
- old = find_inode(sb, head, test, data);
- if (!old) {
- if (set(inode, data))
- goto set_failed;
-
- spin_lock(&inode->i_lock);
- inode->i_state = I_NEW;
- hlist_add_head(&inode->i_hash, head);
- spin_unlock(&inode->i_lock);
- inode_sb_list_add(inode);
- spin_unlock(&inode_hash_lock);
-
- /* Return the locked inode with I_NEW set, the
- * caller is responsible for filling in the contents
- */
- return inode;
- }
+ if (!inode) {
+ struct inode *new = alloc_inode(sb);
- /*
- * Uhhuh, somebody else created the same inode under
- * us. Use the old inode instead of the one we just
- * allocated.
- */
- spin_unlock(&inode_hash_lock);
- destroy_inode(inode);
- inode = old;
- wait_on_inode(inode);
- if (unlikely(inode_unhashed(inode))) {
- iput(inode);
- goto again;
+ if (new) {
+ inode = iget5_prealloc(new, sb, hashval, test, set, data);
+ if (inode != new)
+ destroy_inode(new);
}
}
return inode;
-
-set_failed:
- spin_unlock(&inode_hash_lock);
- destroy_inode(inode);
- return NULL;
}
EXPORT_SYMBOL(iget5_locked);
--
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