fs: Stop abusing find_inode_fast in iunique
Stop abusing find_inode_fast for iunique and opencode the inode hash walk.
Introduce a new iunique_lock to protect the iunique counters once inode_lock
is removed.
Based on a patch originally from Nick Piggin.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/inode.c b/fs/inode.c
index 5e5bafe..a8035e8 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -884,6 +884,27 @@
return inode;
}
+/*
+ * search the inode cache for a matching inode number.
+ * If we find one, then the inode number we are trying to
+ * allocate is not unique and so we should not use it.
+ *
+ * Returns 1 if the inode number is unique, 0 if it is not.
+ */
+static int test_inode_iunique(struct super_block *sb, unsigned long ino)
+{
+ struct hlist_head *b = inode_hashtable + hash(sb, ino);
+ struct hlist_node *node;
+ struct inode *inode;
+
+ hlist_for_each_entry(inode, node, b, i_hash) {
+ if (inode->i_ino == ino && inode->i_sb == sb)
+ return 0;
+ }
+
+ return 1;
+}
+
/**
* iunique - get a unique inode number
* @sb: superblock
@@ -905,19 +926,18 @@
* error if st_ino won't fit in target struct field. Use 32bit counter
* here to attempt to avoid that.
*/
+ static DEFINE_SPINLOCK(iunique_lock);
static unsigned int counter;
- struct inode *inode;
- struct hlist_head *head;
ino_t res;
spin_lock(&inode_lock);
+ spin_lock(&iunique_lock);
do {
if (counter <= max_reserved)
counter = max_reserved + 1;
res = counter++;
- head = inode_hashtable + hash(sb, res);
- inode = find_inode_fast(sb, head, res);
- } while (inode != NULL);
+ } while (!test_inode_iunique(sb, res));
+ spin_unlock(&iunique_lock);
spin_unlock(&inode_lock);
return res;