From 6c0f3af72cb1622a66962a1180c36ef8c41be8e2 Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@newdream.net>
Date: Tue, 16 Nov 2010 11:14:34 -0800
Subject: 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>
---
 fs/ceph/dir.c    | 20 ++++++++++++++++++++
 fs/ceph/export.c |  2 +-
 fs/ceph/inode.c  |  2 ++
 fs/ceph/super.h  |  2 ++
 4 files changed, 25 insertions(+), 1 deletion(-)

(limited to 'fs')

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index d902948a90d8..562f9884a4d9 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1216,6 +1216,26 @@ void ceph_dentry_lru_del(struct dentry *dn)
 	}
 }
 
+/*
+ * 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,
diff --git a/fs/ceph/export.c b/fs/ceph/export.c
index 2297d9426992..e41056174bf8 100644
--- a/fs/ceph/export.c
+++ b/fs/ceph/export.c
@@ -59,7 +59,7 @@ static int ceph_encode_fh(struct dentry *dentry, u32 *rawfh, int *max_len,
 		dout("encode_fh %p connectable\n", dentry);
 		cfh->ino = ceph_ino(dentry->d_inode);
 		cfh->parent_ino = ceph_ino(parent->d_inode);
-		cfh->parent_name_hash = parent->d_name.hash;
+		cfh->parent_name_hash = ceph_dentry_hash(parent);
 		*max_len = connected_handle_length;
 		type = 2;
 	} else if (*max_len >= handle_length) {
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index bf1286588f26..045283ce4413 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -297,6 +297,8 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
 	ci->i_release_count = 0;
 	ci->i_symlink = NULL;
 
+	memset(&ci->i_dir_layout, 0, sizeof(ci->i_dir_layout));
+
 	ci->i_fragtree = RB_ROOT;
 	mutex_init(&ci->i_fragtree_mutex);
 
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 7f01728a4657..6e0826695112 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -239,6 +239,7 @@ struct ceph_inode_info {
 	unsigned i_ceph_flags;
 	unsigned long i_release_count;
 
+	struct ceph_dir_layout i_dir_layout;
 	struct ceph_file_layout i_layout;
 	char *i_symlink;
 
@@ -768,6 +769,7 @@ extern void ceph_dentry_lru_add(struct dentry *dn);
 extern void ceph_dentry_lru_touch(struct dentry *dn);
 extern void ceph_dentry_lru_del(struct dentry *dn);
 extern void ceph_invalidate_dentry_lease(struct dentry *dentry);
+extern unsigned ceph_dentry_hash(struct dentry *dn);
 
 /*
  * our d_ops vary depending on whether the inode is live,
-- 
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