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vfs: make the string hashes salt the hash

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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>
This commit is contained in:
Linus Torvalds
2016-06-10 07:51:30 -07:00
committed by Sebastian Huber
parent fb5bc64d5f
commit 0ec9bbce63
5 changed files with 7 additions and 6 deletions
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2
cpukit/libfs/src/jffs2/src/dir-rtems.c
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@@ -30,7 +30,7 @@ struct _inode *jffs2_lookup(struct _inode *dir_i, const unsigned char *name, siz
struct jffs2_inode_info *dir_f;
struct jffs2_full_dirent *fd = NULL, *fd_list;
uint32_t ino = 0;
uint32_t hash = full_name_hash(name, namelen);
uint32_t hash = full_name_hash(NULL, name, namelen);
struct _inode *inode = NULL;
D1(printk("jffs2_lookup()\n"));

3
cpukit/libfs/src/jffs2/src/os-rtems.h
View File

@@ -41,9 +41,10 @@
struct _inode;
struct super_block;
static inline unsigned int full_name_hash(const unsigned char * name, size_t len) {
static inline unsigned int full_name_hash(const void *salt, const unsigned char * name, size_t len) {
uint32_t hash = 0;
(void)salt;
while (len--) {
hash = (hash << 4) | (hash >> 28);
hash ^= *(name++);

2
cpukit/libfs/src/jffs2/src/readinode.c
View File

@@ -683,7 +683,7 @@ 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';

2
cpukit/libfs/src/jffs2/src/scan.c
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@@ -1103,7 +1103,7 @@ 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);

4
cpukit/libfs/src/jffs2/src/write.c
View File

@@ -247,7 +247,7 @@ 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;
@@ -600,7 +600,7 @@ 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