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Date: Wed, 29 May 2019 14:54:46 -0400
From: Gabriel Krisman Bertazi <krisman@...labora.com>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Gabriel Krisman Bertazi <krisman@...labora.com>
Subject: [PATCH] ext4: Optimize case-insensitive lookups
Temporarily cache a casefolded version of the file name under lookup in
ext4_filename, to avoid repeatedly casefolding it.
This gives me some performance gains on the lookup patch, when
performing cold dcache case-insensitive lookups on directories with a
high number of entries.
Below is a measure of average speedup of several runs with the patch
applied; where the baseline is the currently ext4 code, and the rows are
for different number of directory entries/number of lookup performed.
The speedup is not linear with the number of dentries, which I believe
is because of the changing format of the htree.
| entries | avg speedup |
| 1000 | 1.15 |
| 10000 | 1.19 |
| 50000 | 1.25 |
| 70000 | 1.20 |
| 100000 | 1.13 |
Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>
---
fs/ext4/dir.c | 2 +-
fs/ext4/ext4.h | 32 +++++++++++++++++++++++++++++---
fs/ext4/namei.c | 41 +++++++++++++++++++++++++++++++++++------
fs/unicode/utf8-core.c | 25 +++++++++++++++++++++++++
include/linux/unicode.h | 3 +++
5 files changed, 93 insertions(+), 10 deletions(-)
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index c7843b149a1e..0a427e18584a 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -674,7 +674,7 @@ static int ext4_d_compare(const struct dentry *dentry, unsigned int len,
return memcmp(str, name->name, len);
}
- return ext4_ci_compare(dentry->d_parent->d_inode, name, &qstr);
+ return ext4_ci_compare(dentry->d_parent->d_inode, name, &qstr, false);
}
static int ext4_d_hash(const struct dentry *dentry, struct qstr *str)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index c18ab748d20d..e3809cfda9f4 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2078,6 +2078,10 @@ struct ext4_filename {
#ifdef CONFIG_FS_ENCRYPTION
struct fscrypt_str crypto_buf;
#endif
+#ifdef CONFIG_UNICODE
+ int cf_len;
+ unsigned char cf_name[EXT4_NAME_LEN];
+#endif
};
#define fname_name(p) ((p)->disk_name.name)
@@ -2303,6 +2307,12 @@ extern unsigned ext4_free_clusters_after_init(struct super_block *sb,
struct ext4_group_desc *gdp);
ext4_fsblk_t ext4_inode_to_goal_block(struct inode *);
+#ifdef CONFIG_UNICODE
+extern void ext4_setup_ci_filename(struct inode *dir,
+ const struct qstr *iname,
+ struct ext4_filename *fname);
+#endif
+
#ifdef CONFIG_FS_ENCRYPTION
static inline int ext4_fname_setup_filename(struct inode *dir,
const struct qstr *iname,
@@ -2313,6 +2323,9 @@ static inline int ext4_fname_setup_filename(struct inode *dir,
memset(fname, 0, sizeof(struct ext4_filename));
+#ifdef CONFIG_UNICODE
+ ext4_setup_ci_filename(dir, iname, fname);
+#endif
err = fscrypt_setup_filename(dir, iname, lookup, &name);
fname->usr_fname = name.usr_fname;
@@ -2333,18 +2346,31 @@ static inline void ext4_fname_free_filename(struct ext4_filename *fname)
fname->crypto_buf.name = NULL;
fname->usr_fname = NULL;
fname->disk_name.name = NULL;
+#ifdef CONFIG_UNICODE
+ fname->cf_len = 0;
+#endif
}
#else
static inline int ext4_fname_setup_filename(struct inode *dir,
const struct qstr *iname,
int lookup, struct ext4_filename *fname)
{
+
+#ifdef CONFIG_UNICODE
+ ext4_setup_ci_filename(dir, iname, fname);
+#endif
fname->usr_fname = iname;
fname->disk_name.name = (unsigned char *) iname->name;
fname->disk_name.len = iname->len;
return 0;
}
-static inline void ext4_fname_free_filename(struct ext4_filename *fname) { }
+
+static inline void ext4_fname_free_filename(struct ext4_filename *fname)
+{
+#ifdef CONFIG_UNICODE
+ fname->cf_len = 0;
+#endif
+}
#endif
@@ -3088,8 +3114,8 @@ extern int ext4_handle_dirty_dirent_node(handle_t *handle,
struct inode *inode,
struct buffer_head *bh);
extern int ext4_ci_compare(const struct inode *parent,
- const struct qstr *name,
- const struct qstr *entry);
+ const struct qstr *fname,
+ const struct qstr *entry, bool quick);
#define S_SHIFT 12
static const unsigned char ext4_type_by_mode[(S_IFMT >> S_SHIFT) + 1] = {
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index ac7457fef9e6..082f941520f3 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1259,19 +1259,25 @@ 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)
+int ext4_ci_compare(const struct inode *parent,
+ const struct qstr *name,
+ 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 +1293,21 @@ int ext4_ci_compare(const struct inode *parent, const struct qstr *name,
return ret;
}
+
+void ext4_setup_ci_filename(struct inode *dir,
+ const struct qstr *iname,
+ struct ext4_filename *fname)
+{
+ int len = EXT4_NAME_LEN;
+
+ fname->cf_len = 0;
+ if (IS_CASEFOLDED(dir)) {
+ len = utf8_casefold(EXT4_SB(dir->i_sb)->s_encoding,
+ iname, fname->cf_name, len);
+ if (len >= 0)
+ fname->cf_len = len;
+ }
+}
#endif
/*
@@ -1313,8 +1334,16 @@ 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_len) {
+ struct qstr cf = {.name = fname->cf_name,
+ .len = fname->cf_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);
diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
index 6afab4fdce90..1d74de2778e9 100644
--- a/fs/unicode/utf8-core.c
+++ b/fs/unicode/utf8-core.c
@@ -73,6 +73,31 @@ int utf8_strncasecmp(const struct unicode_map *um,
}
EXPORT_SYMBOL(utf8_strncasecmp);
+int utf8_strncasecmp_folded(const struct unicode_map *um,
+ const struct qstr *normalized,
+ 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 = normalized->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)
{
diff --git a/include/linux/unicode.h b/include/linux/unicode.h
index aec2c6d800aa..e89bf3ecef21 100644
--- a/include/linux/unicode.h
+++ b/include/linux/unicode.h
@@ -17,6 +17,9 @@ int utf8_strncmp(const struct unicode_map *um,
int utf8_strncasecmp(const struct unicode_map *um,
const struct qstr *s1, const struct qstr *s2);
+int utf8_strncasecmp_folded(const struct unicode_map *um,
+ const struct qstr *normalized,
+ const struct qstr *s1);
int utf8_normalize(const struct unicode_map *um, const struct qstr *str,
unsigned char *dest, size_t dlen);
--
2.20.1
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