From 8387ff2577eb9ed245df9a39947f66976c6bcd02 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 10 Jun 2016 07:51:30 -0700 Subject: vfs: make the string hashes salt the hash We always mixed in the parent pointer into the dentry name hash, but we did it late at lookup time. It turns out that we can simplify that lookup-time action by salting the hash with the parent pointer early instead of late. A few other users of our string hashes also wanted to mix in their own pointers into the hash, and those are updated to use the same mechanism. Hash users that don't have any particular initial salt can just use the NULL pointer as a no-salt. Cc: Vegard Nossum Cc: George Spelvin Cc: Al Viro Signed-off-by: Linus Torvalds --- fs/jffs2/dir.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'fs/jffs2/dir.c') diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c index 84c4bf3631a2..30eb33ff8189 100644 --- a/fs/jffs2/dir.c +++ b/fs/jffs2/dir.c @@ -81,6 +81,7 @@ static struct dentry *jffs2_lookup(struct inode *dir_i, struct dentry *target, struct jffs2_full_dirent *fd = NULL, *fd_list; uint32_t ino = 0; struct inode *inode = NULL; + unsigned int nhash; jffs2_dbg(1, "jffs2_lookup()\n"); @@ -89,11 +90,14 @@ static struct dentry *jffs2_lookup(struct inode *dir_i, struct dentry *target, dir_f = JFFS2_INODE_INFO(dir_i); + /* The 'nhash' on the fd_list is not the same as the dentry hash */ + nhash = full_name_hash(NULL, target->d_name.name, target->d_name.len); + mutex_lock(&dir_f->sem); /* NB: The 2.2 backport will need to explicitly check for '.' and '..' here */ - for (fd_list = dir_f->dents; fd_list && fd_list->nhash <= target->d_name.hash; fd_list = fd_list->next) { - if (fd_list->nhash == target->d_name.hash && + for (fd_list = dir_f->dents; fd_list && fd_list->nhash <= nhash; fd_list = fd_list->next) { + if (fd_list->nhash == nhash && (!fd || fd_list->version > fd->version) && strlen(fd_list->name) == target->d_name.len && !strncmp(fd_list->name, target->d_name.name, target->d_name.len)) { -- cgit v1.2.3