linux-ext4 - [PATCH 20/20] ext4: Implement encoding-aware dcache hooks

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Date:   Tue,  3 Jul 2018 13:07:00 -0400
From:   Gabriel Krisman Bertazi <krisman@...labora.co.uk>
To:     tytso@....edu
Cc:     linux-ext4@...r.kernel.org, darrick.wong@...cle.com,
        kernel@...labora.com,
        Gabriel Krisman Bertazi <krisman@...labora.co.uk>
Subject: [PATCH 20/20] ext4: Implement encoding-aware dcache hooks

d_revalidate to reject negative dentries is not needed, because we
avoided adding those in the first place during lookup, similar to what
xfs does.

Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.co.uk>
---
 fs/ext4/dir.c   | 30 ++++++++++++++++++++++++++++++
 fs/ext4/ext4.h  |  1 +
 fs/ext4/super.c |  4 ++++
 3 files changed, 35 insertions(+)

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index e2902d394f1b..c520b9e94778 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -26,6 +26,7 @@
 #include <linux/buffer_head.h>
 #include <linux/slab.h>
 #include <linux/iversion.h>
+#include <linux/nls.h>
 #include "ext4.h"
 #include "xattr.h"
 
@@ -664,3 +665,32 @@ const struct file_operations ext4_dir_operations = {
 	.open		= ext4_dir_open,
 	.release	= ext4_release_dir,
 };
+
+static int ext4_d_compare(const struct dentry *dentry, unsigned int len,
+			  const char *str, const struct qstr *name)
+{
+	struct nls_table *charset = EXT4_SB(dentry->d_sb)->encoding;
+	size_t nlen = strlen(name->name);
+
+	return nls_strncmp(charset, str, len, name->name, nlen);
+}
+
+static int ext4_d_hash(const struct dentry *dentry, struct qstr *q)
+{
+	const struct nls_table *charset = EXT4_SB(dentry->d_sb)->encoding;
+	unsigned char norm[PATH_MAX];
+	int len;
+
+	len = nls_normalize(charset, q->name, q->len, norm, PATH_MAX);
+	if (len < 0)
+		return -EINVAL;
+
+	q->hash = full_name_hash(dentry, norm, len);
+
+	return 0;
+}
+
+const struct dentry_operations ext4_dentry_ops = {
+	.d_hash = ext4_d_hash,
+	.d_compare = ext4_d_compare,
+};
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index fb0b70d6eb68..2a5c7712967f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2953,6 +2953,7 @@ static inline void ext4_unlock_group(struct super_block *sb,
 
 /* dir.c */
 extern const struct file_operations ext4_dir_operations;
+extern const struct dentry_operations ext4_dentry_ops;
 
 /* file.c */
 extern const struct inode_operations ext4_file_inode_operations;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 53db9b6c7e33..f292cc5bacda 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4358,6 +4358,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		iput(root);
 		goto failed_mount4;
 	}
+
+	if (sbi->encoding)
+		sb->s_d_op = &ext4_dentry_ops;
+
 	sb->s_root = d_make_root(root);
 	if (!sb->s_root) {
 		ext4_msg(sb, KERN_ERR, "get root dentry failed");
-- 
2.18.0