From 12f8ad4b0533d9212cb1d5e58ed73d2170114785 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 4 May 2012 14:59:14 -0700
Subject: vfs: clean up __d_lookup_rcu() and dentry_cmp() interfaces

The calling conventions for __d_lookup_rcu() and dentry_cmp() are
annoying in different ways, and there is actually one single underlying
reason for both of the annoyances.

The fundamental reason is that we do the returned dentry sequence number
check inside __d_lookup_rcu() instead of doing it in the caller.  This
results in two annoyances:

 - __d_lookup_rcu() now not only needs to return the dentry and the
   sequence number that goes along with the lookup, it also needs to
   return the inode pointer that was validated by that sequence number
   check.

 - and because we did the sequence number check early (to validate the
   name pointer and length) we also couldn't just pass the dentry itself
   to dentry_cmp(), we had to pass the counted string that contained the
   name.

So that sequence number decision caused two separate ugly calling
conventions.

Both of these problems would be solved if we just did the sequence
number check in the caller instead.  There's only one caller, and that
caller already has to do the sequence number check for the parent
anyway, so just do that.

That allows us to stop returning the dentry->d_inode in that in-out
argument (pointer-to-pointer-to-inode), so we can make the inode
argument just a regular input inode pointer.  The caller can just load
the inode from dentry->d_inode, and then do the sequence number check
after that to make sure that it's synchronized with the name we looked
up.

And it allows us to just pass in the dentry to dentry_cmp(), which is
what all the callers really wanted.  Sure, dentry_cmp() has to be a bit
careful about the dentry (which is not stable during RCU lookup), but
that's actually very simple.

And now that dentry_cmp() can clearly see that the first string argument
is a dentry, we can use the direct word access for that, instead of the
careful unaligned zero-padding.  The dentry name is always properly
aligned, since it is a single path component that is either embedded
into the dentry itself, or was allocated with kmalloc() (see __d_alloc).

Finally, this also uninlines the nasty slow-case for dentry comparisons:
that one *does* need to do a sequence number check, since it will call
in to the low-level filesystems, and we want to give those a stable
inode pointer and path component length/start arguments.  Doing an extra
sequence check for that slow case is not a problem, though.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/dcache.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'include')

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 7e11f1418203..8239f64d1c2e 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -282,7 +282,7 @@ extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
 extern struct dentry *__d_lookup(struct dentry *, struct qstr *);
 extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
 				const struct qstr *name,
-				unsigned *seq, struct inode **inode);
+				unsigned *seq, struct inode *inode);
 
 /**
  * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
-- 
cgit v1.2.3


From 26fe575028703948880fce4355a210c76bb0536e Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 10 May 2012 13:14:12 -0700
Subject: 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>
---
 fs/dcache.c            | 16 +++++++---------
 fs/ext2/namei.c        |  2 +-
 fs/ext3/namei.c        |  2 +-
 fs/ext4/namei.c        |  5 +----
 fs/gfs2/dir.c          |  2 +-
 fs/libfs.c             |  4 ++--
 fs/nfs/dir.c           |  5 +----
 fs/nfs/nfs3proc.c      |  3 +--
 fs/nfs/nfs4proc.c      |  3 +--
 fs/nfs/proc.c          |  3 +--
 fs/nilfs2/namei.c      |  2 +-
 fs/ubifs/tnc.c         |  2 +-
 fs/ubifs/xattr.c       |  6 +++---
 fs/udf/namei.c         |  2 +-
 fs/ufs/super.c         |  5 +----
 include/linux/dcache.h | 19 +++++++++++++++++--
 net/sunrpc/clnt.c      |  4 +---
 net/sunrpc/rpc_pipe.c  |  7 ++-----
 18 files changed, 44 insertions(+), 48 deletions(-)

(limited to 'include')

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);
-- 
cgit v1.2.3