From 26fe575028703948880fce4355a210c76bb0536e Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 10 May 2012 13:14:12 -0700 Subject: 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: Linus Torvalds --- include/linux/dcache.h | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'include/linux/dcache.h') diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 8239f64d1c2e..094789ff3e9f 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -25,6 +25,13 @@ struct vfsmount; #define IS_ROOT(x) ((x) == (x)->d_parent) +/* The hash is always the low bits of hash_len */ +#ifdef __LITTLE_ENDIAN + #define HASH_LEN_DECLARE u32 hash; u32 len; +#else + #define HASH_LEN_DECLARE u32 len; u32 hash; +#endif + /* * "quick string" -- eases parameter passing, but more importantly * saves "metadata" about the string (ie length and the hash). @@ -33,11 +40,19 @@ struct vfsmount; * dentry. */ struct qstr { - unsigned int hash; - unsigned int len; + union { + struct { + HASH_LEN_DECLARE; + }; + u64 hash_len; + }; const unsigned char *name; }; +#define QSTR_INIT(n,l) { { { .len = l } }, .name = n } +#define hashlen_hash(hashlen) ((u32) (hashlen)) +#define hashlen_len(hashlen) ((u32)((hashlen) >> 32)) + struct dentry_stat_t { int nr_dentry; int nr_unused; -- cgit v1.2.2