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 <vegard.nossum@oracle.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 11 insertions, 7 deletions

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)) {
diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index bfebbf13698c..06a71dbd4833 100644
--- a/fs/jffs2/readinode.c
+++ b/fs/jffs2/readinode.c
@@ -674,7 +674,7 @@ static inline int read_direntry(struct jffs2_sb_info *c, struct jffs2_raw_node_r
 		}
 	}
 
-	fd->nhash = full_name_hash(fd->name, rd->nsize);
+	fd->nhash = full_name_hash(NULL, fd->name, rd->nsize);
 	fd->next = NULL;
 	fd->name[rd->nsize] = '\0';
 
diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index 9ad5ba4b299b..90431dd613b8 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -1100,7 +1100,7 @@ static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblo
 	fd->next = NULL;
 	fd->version = je32_to_cpu(rd->version);
 	fd->ino = je32_to_cpu(rd->ino);
-	fd->nhash = full_name_hash(fd->name, checkedlen);
+	fd->nhash = full_name_hash(NULL, fd->name, checkedlen);
 	fd->type = rd->type;
 	jffs2_add_fd_to_list(c, fd, &ic->scan_dents);
 
diff --git a/fs/jffs2/summary.c b/fs/jffs2/summary.c
index bc5385471a6e..be7c8a6a5748 100644
--- a/fs/jffs2/summary.c
+++ b/fs/jffs2/summary.c
@@ -476,7 +476,7 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
 				fd->next = NULL;
 				fd->version = je32_to_cpu(spd->version);
 				fd->ino = je32_to_cpu(spd->ino);
-				fd->nhash = full_name_hash(fd->name, checkedlen);
+				fd->nhash = full_name_hash(NULL, fd->name, checkedlen);
 				fd->type = spd->type;
 
 				jffs2_add_fd_to_list(c, fd, &ic->scan_dents);
diff --git a/fs/jffs2/write.c b/fs/jffs2/write.c
index 7fb187ab2682..cda9a361368e 100644
--- a/fs/jffs2/write.c
+++ b/fs/jffs2/write.c
@@ -245,7 +245,7 @@ struct jffs2_full_dirent *jffs2_write_dirent(struct jffs2_sb_info *c, struct jff
 
 	fd->version = je32_to_cpu(rd->version);
 	fd->ino = je32_to_cpu(rd->ino);
-	fd->nhash = full_name_hash(name, namelen);
+	fd->nhash = full_name_hash(NULL, name, namelen);
 	fd->type = rd->type;
 	memcpy(fd->name, name, namelen);
 	fd->name[namelen]=0;
@@ -598,7 +598,7 @@ int jffs2_do_unlink(struct jffs2_sb_info *c, struct jffs2_inode_info *dir_f,
 		jffs2_add_fd_to_list(c, fd, &dir_f->dents);
 		mutex_unlock(&dir_f->sem);
 	} else {
-		uint32_t nhash = full_name_hash(name, namelen);
+		uint32_t nhash = full_name_hash(NULL, name, namelen);
 
 		fd = dir_f->dents;
 		/* We don't actually want to reserve any space, but we do