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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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43
fs/ext4/namei.c
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@@ -1259,19 +1259,24 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)
#ifdef CONFIG_UNICODE
/*
* Test whether a case-insensitive directory entry matches the filename
* being searched for.
* being searched for. If quick is set, assume the name being looked up
* is already in the casefolded form.
*
* Returns: 0 if the directory entry matches, more than 0 if it
* doesn't match or less than zero on error.
*/
int ext4_ci_compare(const struct inode *parent, const struct qstr *name,
const struct qstr *entry)
const struct qstr *entry, bool quick)
{
const struct ext4_sb_info *sbi = EXT4_SB(parent->i_sb);
const struct unicode_map *um = sbi->s_encoding;
int ret;
ret = utf8_strncasecmp(um, name, entry);
if (quick)
ret = utf8_strncasecmp_folded(um, name, entry);
else
ret = utf8_strncasecmp(um, name, entry);
if (ret < 0) {
/* Handle invalid character sequence as either an error
* or as an opaque byte sequence.
@@ -1287,6 +1292,27 @@ int ext4_ci_compare(const struct inode *parent, const struct qstr *name,
return ret;
}
void ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname,
struct fscrypt_str *cf_name)
{
if (!IS_CASEFOLDED(dir)) {
cf_name->name = NULL;
return;
}
cf_name->name = kmalloc(EXT4_NAME_LEN, GFP_NOFS);
if (!cf_name->name)
return;
cf_name->len = utf8_casefold(EXT4_SB(dir->i_sb)->s_encoding,
iname, cf_name->name,
EXT4_NAME_LEN);
if (cf_name->len <= 0) {
kfree(cf_name->name);
cf_name->name = NULL;
}
}
#endif
/*
@@ -1313,8 +1339,15 @@ static inline bool ext4_match(const struct inode *parent,
#endif
#ifdef CONFIG_UNICODE
if (EXT4_SB(parent->i_sb)->s_encoding && IS_CASEFOLDED(parent))
return (ext4_ci_compare(parent, fname->usr_fname, &entry) == 0);
if (EXT4_SB(parent->i_sb)->s_encoding && IS_CASEFOLDED(parent)) {
if (fname->cf_name.name) {
struct qstr cf = {.name = fname->cf_name.name,
.len = fname->cf_name.len};
return !ext4_ci_compare(parent, &cf, &entry, true);
}
return !ext4_ci_compare(parent, fname->usr_fname, &entry,
false);
}
#endif
return fscrypt_match_name(&f, de->name, de->name_len);