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>

18 files changed, 44 insertions, 48 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index e6707a1f72c6..92099f61bc64 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1502,7 +1502,7 @@ struct dentry *d_make_root(struct inode *root_inode)
         struct dentry *res = NULL;
 
         if (root_inode) {
-                static const struct qstr name = { .name = "/", .len = 1 };
+                static const struct qstr name = QSTR_INIT("/", 1);
 
                 res = __d_alloc(root_inode->i_sb, &name);
                 if (res)
@@ -1816,10 +1816,9 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent,
                                 const struct qstr *name,
                                 unsigned *seqp, struct inode *inode)
 {
-        unsigned int len = name->len;
-        unsigned int hash = name->hash;
+        u64 hashlen = name->hash_len;
         const unsigned char *str = name->name;
-        struct hlist_bl_head *b = d_hash(parent, hash);
+        struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen));
         struct hlist_bl_node *node;
         struct dentry *dentry;
 
@@ -1846,9 +1845,6 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent,
         hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
                 unsigned seq;
 
-                if (dentry->d_name.hash != hash)
-                        continue;
-
 seqretry:
                 /*
                  * The dentry sequence count protects us from concurrent
@@ -1871,6 +1867,8 @@ seqretry:
                 *seqp = seq;
 
                 if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
+                        if (dentry->d_name.hash != hashlen_hash(hashlen))
+                                continue;
                         switch (slow_dentry_cmp(parent, inode, dentry, seq, name)) {
                         case D_COMP_OK:
                                 return dentry;
@@ -1881,9 +1879,9 @@ seqretry:
                         }
                 }
 
-                if (dentry->d_name.len != len)
+                if (dentry->d_name.hash_len != hashlen)
                         continue;
-                if (!dentry_cmp(dentry, str, len))
+                if (!dentry_cmp(dentry, str, hashlen_len(hashlen)))
                         return dentry;
         }
         return NULL;
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index dffb86536285..f663a67d7bf0 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -79,7 +79,7 @@ static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, str
 
 struct dentry *ext2_get_parent(struct dentry *child)
 {
-        struct qstr dotdot = {.name = "..", .len = 2};
+        struct qstr dotdot = QSTR_INIT("..", 2);
         unsigned long ino = ext2_inode_by_name(child->d_inode, &dotdot);
         if (!ino)
                 return ERR_PTR(-ENOENT);
diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c
index d7940b24cf68..eeb63dfc5d20 100644
--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -1045,7 +1045,7 @@ static struct dentry *ext3_lookup(struct inode * dir, struct dentry *dentry, str
 struct dentry *ext3_get_parent(struct dentry *child)
 {
         unsigned long ino;
-        struct qstr dotdot = {.name = "..", .len = 2};
+        struct qstr dotdot = QSTR_INIT("..", 2);
         struct ext3_dir_entry_2 * de;
         struct buffer_head *bh;
 
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 349d7b3671c8..e2a3f4b0ff78 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1052,10 +1052,7 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, stru
 struct dentry *ext4_get_parent(struct dentry *child)
 {
         __u32 ino;
-        static const struct qstr dotdot = {
-                .name = "..",
-                .len = 2,
-        };
+        static const struct qstr dotdot = QSTR_INIT("..", 2);
         struct ext4_dir_entry_2 * de;
         struct buffer_head *bh;
 
diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
index a836056343f0..8aaeb07a07b5 100644
--- a/fs/gfs2/dir.c
+++ b/fs/gfs2/dir.c
@@ -821,7 +821,7 @@ static struct gfs2_leaf *new_leaf(struct inode *inode, struct buffer_head **pbh,
         struct buffer_head *bh;
         struct gfs2_leaf *leaf;
         struct gfs2_dirent *dent;
-        struct qstr name = { .name = "", .len = 0, .hash = 0 };
+        struct qstr name = { .name = "" };
 
         error = gfs2_alloc_blocks(ip, &bn, &n, 0, NULL);
         if (error)
diff --git a/fs/libfs.c b/fs/libfs.c
index 18d08f5db53a..f86ec27a4230 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -68,7 +68,7 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct na
 
 int dcache_dir_open(struct inode *inode, struct file *file)
 {
-        static struct qstr cursor_name = {.len = 1, .name = "."};
+        static struct qstr cursor_name = QSTR_INIT(".", 1);
 
         file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
 
@@ -225,7 +225,7 @@ struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name,
         struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
         struct dentry *dentry;
         struct inode *root;
-        struct qstr d_name = {.name = name, .len = strlen(name)};
+        struct qstr d_name = QSTR_INIT(name, strlen(name));
 
         if (IS_ERR(s))
                 return ERR_CAST(s);
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 8789210c6905..eedd24d0ad2e 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -477,10 +477,7 @@ different:
 static
 void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry)
 {
-        struct qstr filename = {
-                .len = entry->len,
-                .name = entry->name,
-        };
+        struct qstr filename = QSTR_INIT(entry->name, entry->len);
         struct dentry *dentry;
         struct dentry *alias;
         struct inode *dir = parent->d_inode;
diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index 5242eae6711a..75c68299358e 100644
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -398,8 +398,7 @@ nfs3_proc_remove(struct inode *dir, struct qstr *name)
 {
         struct nfs_removeargs arg = {
                 .fh = NFS_FH(dir),
-                .name.len = name->len,
-                .name.name = name->name,
+                .name = *name,
         };
         struct nfs_removeres res;
         struct rpc_message msg = {
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 99650aaf8937..ab985f6f0da8 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2782,8 +2782,7 @@ static int _nfs4_proc_remove(struct inode *dir, struct qstr *name)
         struct nfs_server *server = NFS_SERVER(dir);
         struct nfs_removeargs args = {
                 .fh = NFS_FH(dir),
-                .name.len = name->len,
-                .name.name = name->name,
+                .name = *name,
                 .bitmask = server->attr_bitmask,
         };
         struct nfs_removeres res = {
diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
index b63b6f4d14fb..d6408b6437de 100644
--- a/fs/nfs/proc.c
+++ b/fs/nfs/proc.c
@@ -335,8 +335,7 @@ nfs_proc_remove(struct inode *dir, struct qstr *name)
 {
         struct nfs_removeargs arg = {
                 .fh = NFS_FH(dir),
-                .name.len = name->len,
-                .name.name = name->name,
+                .name = *name,
         };
         struct rpc_message msg = { 
                 .rpc_proc = &nfs_procedures[NFSPROC_REMOVE],
diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
index fce2bbee66d4..0bb2c2010b95 100644
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -441,7 +441,7 @@ static struct dentry *nilfs_get_parent(struct dentry *child)
 {
         unsigned long ino;
         struct inode *inode;
-        struct qstr dotdot = {.name = "..", .len = 2};
+        struct qstr dotdot = QSTR_INIT("..", 2);
         struct nilfs_root *root;
 
         ino = nilfs_inode_by_name(child->d_inode, &dotdot);
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 16ad84d8402f..abd51331345e 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -2361,7 +2361,7 @@ int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
                          * by passing 'ubifs_tnc_remove_nm()' the same key but
                          * an unmatchable name.
                          */
-                        struct qstr noname = { .len = 0, .name = "" };
+                        struct qstr noname = { .name = "" };
 
                         err = dbg_check_tnc(c, 0);
                         mutex_unlock(&c->tnc_mutex);
diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
index 85b272268754..7a8bafa19c9f 100644
--- a/fs/ubifs/xattr.c
+++ b/fs/ubifs/xattr.c
@@ -298,7 +298,7 @@ int ubifs_setxattr(struct dentry *dentry, const char *name,
 {
         struct inode *inode, *host = dentry->d_inode;
         struct ubifs_info *c = host->i_sb->s_fs_info;
-        struct qstr nm = { .name = name, .len = strlen(name) };
+        struct qstr nm = QSTR_INIT(name, strlen(name));
         struct ubifs_dent_node *xent;
         union ubifs_key key;
         int err, type;
@@ -361,7 +361,7 @@ ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
 {
         struct inode *inode, *host = dentry->d_inode;
         struct ubifs_info *c = host->i_sb->s_fs_info;
-        struct qstr nm = { .name = name, .len = strlen(name) };
+        struct qstr nm = QSTR_INIT(name, strlen(name));
         struct ubifs_inode *ui;
         struct ubifs_dent_node *xent;
         union ubifs_key key;
@@ -524,7 +524,7 @@ int ubifs_removexattr(struct dentry *dentry, const char *name)
 {
         struct inode *inode, *host = dentry->d_inode;
         struct ubifs_info *c = host->i_sb->s_fs_info;
-        struct qstr nm = { .name = name, .len = strlen(name) };
+        struct qstr nm = QSTR_INIT(name, strlen(name));
         struct ubifs_dent_node *xent;
         union ubifs_key key;
         int err;
diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index 38de8f234b94..a165c66e3eef 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -1193,7 +1193,7 @@ static struct dentry *udf_get_parent(struct dentry *child)
 {
         struct kernel_lb_addr tloc;
         struct inode *inode = NULL;
-        struct qstr dotdot = {.name = "..", .len = 2};
+        struct qstr dotdot = QSTR_INIT("..", 2);
         struct fileIdentDesc cfi;
         struct udf_fileident_bh fibh;
 
diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index ac8e279eccc6..302f340d0071 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -146,10 +146,7 @@ static struct dentry *ufs_fh_to_parent(struct super_block *sb, struct fid *fid,
 
 static struct dentry *ufs_get_parent(struct dentry *child)
 {
-        struct qstr dot_dot = {
-                .name   = "..",
-                .len    = 2,
-        };
+        struct qstr dot_dot = QSTR_INIT("..", 2);
         ino_t ino;
 
         ino = ufs_inode_by_name(child->d_inode, &dot_dot);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 8239f64d1c2e..094789ff3e9f 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -25,6 +25,13 @@ struct vfsmount;
 
 #define IS_ROOT(x) ((x) == (x)->d_parent)
 
+/* The hash is always the low bits of hash_len */
+#ifdef __LITTLE_ENDIAN
+ #define HASH_LEN_DECLARE u32 hash; u32 len;
+#else
+ #define HASH_LEN_DECLARE u32 len; u32 hash;
+#endif
+
 /*
  * "quick string" -- eases parameter passing, but more importantly
  * saves "metadata" about the string (ie length and the hash).
@@ -33,11 +40,19 @@ struct vfsmount;
  * dentry.
  */
 struct qstr {
-        unsigned int hash;
-        unsigned int len;
+        union {
+                struct {
+                        HASH_LEN_DECLARE;
+                };
+                u64 hash_len;
+        };
         const unsigned char *name;
 };
 
+#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
+#define hashlen_hash(hashlen) ((u32) (hashlen))
+#define hashlen_len(hashlen)  ((u32)((hashlen) >> 32))
+
 struct dentry_stat_t {
         int nr_dentry;
         int nr_unused;
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index adf2990acebf..7fee13b331d1 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 3b62cf288031..fd2423991c2d 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);