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author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-10 13:14:12 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-10 19:54:35 -0700 |
commit | 26fe575028703948880fce4355a210c76bb0536e (patch) | |
tree | 0a7d04289e1eb1f1739659ebc9498d40f2add5da /include/linux/dcache.h | |
parent | ee983e89670704b2a05e897b161f2674a42d1508 (diff) | |
download | linux-stable-26fe575028703948880fce4355a210c76bb0536e.tar.gz linux-stable-26fe575028703948880fce4355a210c76bb0536e.tar.bz2 linux-stable-26fe575028703948880fce4355a210c76bb0536e.zip |
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 <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/dcache.h')
-rw-r--r-- | include/linux/dcache.h | 19 |
1 files changed, 17 insertions, 2 deletions
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; |