ceph: add dir_layout to inode
Add a ceph_dir_layout to the inode, and calculate dentry hash values based
on the parent directory's specified dir_hash function. This is needed
because the old default Linux dcache hash function is extremely week and
leads to a poor distribution of files among dir fragments.
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index d902948..562f988 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1216,6 +1216,26 @@
}
}
+/*
+ * Return name hash for a given dentry. This is dependent on
+ * the parent directory's hash function.
+ */
+unsigned ceph_dentry_hash(struct dentry *dn)
+{
+ struct inode *dir = dn->d_parent->d_inode;
+ struct ceph_inode_info *dci = ceph_inode(dir);
+
+ switch (dci->i_dir_layout.dl_dir_hash) {
+ case 0: /* for backward compat */
+ case CEPH_STR_HASH_LINUX:
+ return dn->d_name.hash;
+
+ default:
+ return ceph_str_hash(dci->i_dir_layout.dl_dir_hash,
+ dn->d_name.name, dn->d_name.len);
+ }
+}
+
const struct file_operations ceph_dir_fops = {
.read = ceph_read_dir,
.readdir = ceph_readdir,