vfs: make it possible to access the dentry hash/len as one 64-bit entry

This allows comparing hash and len in one operation on 64-bit
architectures.  Right now only __d_lookup_rcu() takes advantage of this,
since that is the case we care most about.

The use of anonymous struct/unions hides the alternate 64-bit approach
from most users, the exception being a few cases where we initialize a
'struct qstr' with a static initializer.  This makes the problematic
cases use a new QSTR_INIT() helper function for that (but initializing
just the name pointer with a "{ .name = xyzzy }" initializer remains
valid, as does just copying another qstr structure).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3 insertions, 8 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index adf2990..7fee13b 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -127,9 +127,7 @@ static struct dentry *rpc_setup_pipedir_sb(struct super_block *sb,
 {
 	static uint32_t clntid;
 	char name[15];
-	struct qstr q = {
-		.name = name,
-	};
+	struct qstr q = { .name = name };
 	struct dentry *dir, *dentry;
 	int error;
 
diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index 3b62cf2..fd24239 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -1059,12 +1059,9 @@ static const struct rpc_filelist files[] = {
 struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
 			       const unsigned char *dir_name)
 {
-	struct qstr dir = {
-		.name = dir_name,
-		.len = strlen(dir_name),
-		.hash = full_name_hash(dir_name, strlen(dir_name)),
-	};
+	struct qstr dir = QSTR_INIT(dir_name, strlen(dir_name));
 
+	dir.hash = full_name_hash(dir.name, dir.len);
 	return d_lookup(sb->s_root, &dir);
 }
 EXPORT_SYMBOL_GPL(rpc_d_lookup_sb);