ext3: provide function to release metadata pages under memory pressure

[safe/jmp/linux-2.6] / fs / ext3 / hash.c

diff --git a/fs/ext3/hash.c b/fs/ext3/hash.c
index 5a2d123..7d215b4 100644 (file)
--- a/fs/ext3/hash.c
+++ b/fs/ext3/hash.c
@@ -4,14 +4,13 @@
  * Copyright (C) 2002 by Theodore Ts'o
  *
  * This file is released under the GPL v2.
- * 
+ *
  * This file may be redistributed under the terms of the GNU Public
  * License.
  */
 
 #include <linux/fs.h>
 #include <linux/jbd.h>
-#include <linux/sched.h>
 #include <linux/ext3_fs.h>
 #include <linux/cryptohash.h>
 
@@ -36,23 +35,71 @@ static void TEA_transform(__u32 buf[4], __u32 const in[])
 
 
 /* The old legacy hash */
-static __u32 dx_hack_hash (const char *name, int len)
+static __u32 dx_hack_hash_unsigned(const char *name, int len)
 {
-       __u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+       __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+       const unsigned char *ucp = (const unsigned char *) name;
+
        while (len--) {
-               __u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));
+               hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
 
-               if (hash & 0x80000000) hash -= 0x7fffffff;
+               if (hash & 0x80000000)
+                       hash -= 0x7fffffff;
                hash1 = hash0;
                hash0 = hash;
        }
-       return (hash0 << 1);
+       return hash0 << 1;
+}
+
+static __u32 dx_hack_hash_signed(const char *name, int len)
+{
+       __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+       const signed char *scp = (const signed char *) name;
+
+       while (len--) {
+               hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
+
+               if (hash & 0x80000000)
+                       hash -= 0x7fffffff;
+               hash1 = hash0;
+               hash0 = hash;
+       }
+       return hash0 << 1;
+}
+
+static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
+{
+       __u32   pad, val;
+       int     i;
+       const signed char *scp = (const signed char *) msg;
+
+       pad = (__u32)len | ((__u32)len << 8);
+       pad |= pad << 16;
+
+       val = pad;
+       if (len > num*4)
+               len = num * 4;
+       for (i = 0; i < len; i++) {
+               if ((i % 4) == 0)
+                       val = pad;
+               val = ((int) scp[i]) + (val << 8);
+               if ((i % 4) == 3) {
+                       *buf++ = val;
+                       val = pad;
+                       num--;
+               }
+       }
+       if (--num >= 0)
+               *buf++ = val;
+       while (--num >= 0)
+               *buf++ = pad;
 }
 
-static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
+static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
 {
        __u32   pad, val;
        int     i;
+       const unsigned char *ucp = (const unsigned char *) msg;
 
        pad = (__u32)len | ((__u32)len << 8);
        pad |= pad << 16;
@@ -63,7 +110,7 @@ static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
        for (i=0; i < len; i++) {
                if ((i % 4) == 0)
                        val = pad;
-               val = msg[i] + (val << 8);
+               val = ((int) ucp[i]) + (val << 8);
                if ((i % 4) == 3) {
                        *buf++ = val;
                        val = pad;
@@ -80,11 +127,11 @@ static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
  * Returns the hash of a filename.  If len is 0 and name is NULL, then
  * this function can be used to test whether or not a hash version is
  * supported.
- * 
+ *
  * The seed is an 4 longword (32 bits) "secret" which can be used to
  * uniquify a hash.  If the seed is all zero's, then some default seed
  * may be used.
- * 
+ *
  * A particular hash version specifies whether or not the seed is
  * represented, and whether or not the returned hash is 32 bits or 64
  * bits.  32 bit hashes will return 0 for the minor hash.
@@ -95,7 +142,9 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
        __u32   minor_hash = 0;
        const char      *p;
        int             i;
-       __u32           in[8], buf[4];
+       __u32           in[8], buf[4];
+       void            (*str2hashbuf)(const char *, int, __u32 *, int) =
+                               str2hashbuf_signed;
 
        /* Initialize the default seed for the hash checksum functions */
        buf[0] = 0x67452301;
@@ -114,13 +163,18 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
        }
 
        switch (hinfo->hash_version) {
+       case DX_HASH_LEGACY_UNSIGNED:
+               hash = dx_hack_hash_unsigned(name, len);
+               break;
        case DX_HASH_LEGACY:
-               hash = dx_hack_hash(name, len);
+               hash = dx_hack_hash_signed(name, len);
                break;
+       case DX_HASH_HALF_MD4_UNSIGNED:
+               str2hashbuf = str2hashbuf_unsigned;
        case DX_HASH_HALF_MD4:
                p = name;
                while (len > 0) {
-                       str2hashbuf(p, len, in, 8);
+                       (*str2hashbuf)(p, len, in, 8);
                        half_md4_transform(buf, in);
                        len -= 32;
                        p += 32;
@@ -128,10 +182,12 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
                minor_hash = buf[2];
                hash = buf[1];
                break;
+       case DX_HASH_TEA_UNSIGNED:
+               str2hashbuf = str2hashbuf_unsigned;
        case DX_HASH_TEA:
                p = name;
                while (len > 0) {
-                       str2hashbuf(p, len, in, 4);
+                       (*str2hashbuf)(p, len, in, 4);
                        TEA_transform(buf, in);
                        len -= 16;
                        p += 16;