ext4: optimize case-insensitive lookups

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>

1 files changed, 36 insertions, 3 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ceb74093e138..7215a2a2a0de 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2078,6 +2078,9 @@ struct ext4_filename {
 #ifdef CONFIG_FS_ENCRYPTION
         struct fscrypt_str crypto_buf;
 #endif
+#ifdef CONFIG_UNICODE
+        struct fscrypt_str cf_name;
+#endif
 };
 
 #define fname_name(p) ((p)->disk_name.name)
@@ -2303,6 +2306,12 @@ 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_fname_setup_ci_filename(struct inode *dir,
+                                         const struct qstr *iname,
+                                         struct fscrypt_str *fname);
+#endif
+
 #ifdef CONFIG_FS_ENCRYPTION
 static inline void ext4_fname_from_fscrypt_name(struct ext4_filename *dst,
                                                 const struct fscrypt_name *src)
@@ -2329,6 +2338,10 @@ static inline int ext4_fname_setup_filename(struct inode *dir,
                 return err;
 
         ext4_fname_from_fscrypt_name(fname, &name);
+
+#ifdef CONFIG_UNICODE
+        ext4_fname_setup_ci_filename(dir, iname, &fname->cf_name);
+#endif
         return 0;
 }
 
@@ -2344,6 +2357,10 @@ static inline int ext4_fname_prepare_lookup(struct inode *dir,
                 return err;
 
         ext4_fname_from_fscrypt_name(fname, &name);
+
+#ifdef CONFIG_UNICODE
+        ext4_fname_setup_ci_filename(dir, &dentry->d_name, &fname->cf_name);
+#endif
         return 0;
 }
 
@@ -2357,6 +2374,11 @@ 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
+        kfree(fname->cf_name.name);
+        fname->cf_name.name = NULL;
+#endif
 }
 #else /* !CONFIG_FS_ENCRYPTION */
 static inline int ext4_fname_setup_filename(struct inode *dir,
@@ -2367,6 +2389,11 @@ static inline int ext4_fname_setup_filename(struct inode *dir,
         fname->usr_fname = iname;
         fname->disk_name.name = (unsigned char *) iname->name;
         fname->disk_name.len = iname->len;
+
+#ifdef CONFIG_UNICODE
+        ext4_fname_setup_ci_filename(dir, iname, &fname->cf_name);
+#endif
+
         return 0;
 }
 
@@ -2377,7 +2404,13 @@ static inline int ext4_fname_prepare_lookup(struct inode *dir,
         return ext4_fname_setup_filename(dir, &dentry->d_name, 1, fname);
 }
 
-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
+        kfree(fname->cf_name.name);
+        fname->cf_name.name = NULL;
+#endif
+}
 #endif /* !CONFIG_FS_ENCRYPTION */
 
 /* dir.c */
@@ -3120,8 +3153,8 @@ 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] = {