Commit 4cb64024 authored by Al Viro's avatar Al Viro
Browse files

lookup_fast(): don't bother with inode 



Note that validation of ->d_seq after ->d_inode fetch is gone, along
with fetching of ->d_inode itself.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b16c001d

fs/namei.c

+4 −18
Original line number Diff line number Diff line
@@ -1621,8 +1621,7 @@ static struct dentry *__lookup_hash(const struct qstr *name, 
	return dentry;

}



static struct dentry *lookup_fast(struct nameidata *nd,

				  struct inode **inode)

static struct dentry *lookup_fast(struct nameidata *nd)

{

	struct dentry *dentry, *parent = nd->path.dentry;

	int status = 1;
@@ -1640,22 +1639,11 @@ static struct dentry *lookup_fast(struct nameidata *nd, 
			return NULL;

		}



		/*

		 * This sequence count validates that the inode matches

		 * the dentry name information from lookup.

		 */

		*inode = d_backing_inode(dentry);

		if (read_seqcount_retry(&dentry->d_seq, nd->next_seq))

			return ERR_PTR(-ECHILD);



		/*

		 * This sequence count validates that the parent had no

		 * changes while we did the lookup of the dentry above.

		 *

		 * The memory barrier in read_seqcount_begin of child is

		 *  enough, we can use __read_seqcount_retry here.

		 */

		if (__read_seqcount_retry(&parent->d_seq, nd->seq))

		if (read_seqcount_retry(&parent->d_seq, nd->seq))

			return ERR_PTR(-ECHILD);



		status = d_revalidate(dentry, nd->flags);
@@ -1997,7 +1985,6 @@ static const char *handle_dots(struct nameidata *nd, int type) 
static const char *walk_component(struct nameidata *nd, int flags)

{

	struct dentry *dentry;

	struct inode *inode;

	/*

	 * "." and ".." are special - ".." especially so because it has

	 * to be able to know about the current root directory and
@@ -2008,7 +1995,7 @@ static const char *walk_component(struct nameidata *nd, int flags) 
			put_link(nd);

		return handle_dots(nd, nd->last_type);

	}

	dentry = lookup_fast(nd, &inode);

	dentry = lookup_fast(nd);

	if (IS_ERR(dentry))

		return ERR_CAST(dentry);

	if (unlikely(!dentry)) {
@@ -3396,7 +3383,6 @@ static const char *open_last_lookups(struct nameidata *nd, 
	struct dentry *dir = nd->path.dentry;

	int open_flag = op->open_flag;

	bool got_write = false;

	struct inode *inode;

	struct dentry *dentry;

	const char *res;
@@ -3412,7 +3398,7 @@ static const char *open_last_lookups(struct nameidata *nd, 
		if (nd->last.name[nd->last.len])

			nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;

		/* we _can_ be in RCU mode here */

		dentry = lookup_fast(nd, &inode);

		dentry = lookup_fast(nd);

		if (IS_ERR(dentry))

			return ERR_CAST(dentry);

		if (likely(dentry))