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ext4: optimize case-insensitive lookups

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Temporarily cache a casefolded version of the file name under lookup in
ext4_filename, to avoid repeatedly casefolding it.  I got up to 30%
speedup on lookups of large directories (>100k entries), depending on
the length of the string under lookup.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Gabriel Krisman Bertazi
2019-06-19 23:45:09 -04:00
committed by Theodore Ts'o
parent b03755ad6f
commit 3ae72562ad
5 changed files with 106 additions and 9 deletions
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28
fs/unicode/utf8-core.c
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@@ -73,6 +73,34 @@ int utf8_strncasecmp(const struct unicode_map *um,
}
EXPORT_SYMBOL(utf8_strncasecmp);
/* String cf is expected to be a valid UTF-8 casefolded
* string.
*/
int utf8_strncasecmp_folded(const struct unicode_map *um,
const struct qstr *cf,
const struct qstr *s1)
{
const struct utf8data *data = utf8nfdicf(um->version);
struct utf8cursor cur1;
int c1, c2;
int i = 0;
if (utf8ncursor(&cur1, data, s1->name, s1->len) < 0)
return -EINVAL;
do {
c1 = utf8byte(&cur1);
c2 = cf->name[i++];
if (c1 < 0)
return -EINVAL;
if (c1 != c2)
return 1;
} while (c1);
return 0;
}
EXPORT_SYMBOL(utf8_strncasecmp_folded);
int utf8_casefold(const struct unicode_map *um, const struct qstr *str,
unsigned char *dest, size_t dlen)
{