Commit 26fe5750 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ee983e89

fs/dcache.c

+7 −9
Original line number Diff line number Diff line
@@ -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;

fs/ext2/namei.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

fs/ext3/namei.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

fs/ext4/namei.c

+1 −4
Original line number Diff line number Diff line
@@ -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;

fs/gfs2/dir.c

+1 −1
Original line number Diff line number Diff line
@@ -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)

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