[RFC PATCH v2 17/18] cifs: Remove usage of load_nls_default() calls

["Pali Rohár" <pali@kernel.org>]

cifs functions will use UTF-8 encoding when nls_table is set to NULL. So
there is no need to load "dummy" NLS table for some operations.

On few places in dfs_cache replace utf8 nls by utf8_to_utf32() function
which converts UTF-8 sequence to unicode code points (stored as type
unicode_t). This should fix handling of (UTF-16) CIFS paths with UTF-16
surrogare pairs, which utf8 nls module cannot handle.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 fs/cifs/cifssmb.c   |  8 ++------
 fs/cifs/dfs_cache.c | 24 ++++++++----------------
 fs/cifs/smb2pdu.c   | 18 ++++--------------
 3 files changed, 14 insertions(+), 36 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 23f10e0d6e7e..3db882fdc21d 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -69,7 +69,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	int rc;
 	struct cifs_ses *ses;
 	struct TCP_Server_Info *server;
-	struct nls_table *nls_codepage;
 	int retries;
 
 	/*
@@ -147,8 +146,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	}
 	spin_unlock(&ses->chan_lock);
 
-	nls_codepage = load_nls_default();
-
 	/*
 	 * Recheck after acquire mutex. If another thread is negotiating
 	 * and the server never sends an answer the socket will be closed
@@ -182,7 +179,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	mutex_lock(&ses->session_mutex);
 	rc = cifs_negotiate_protocol(0, ses, server);
 	if (!rc)
-		rc = cifs_setup_session(0, ses, server, nls_codepage);
+		rc = cifs_setup_session(0, ses, server, NULL);
 
 	/* do we need to reconnect tcon? */
 	if (rc || !tcon->need_reconnect) {
@@ -192,7 +189,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 
 skip_sess_setup:
 	cifs_mark_open_files_invalid(tcon);
-	rc = cifs_tree_connect(0, tcon, nls_codepage);
+	rc = cifs_tree_connect(0, tcon, NULL);
 	mutex_unlock(&ses->session_mutex);
 	cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);
 
@@ -228,7 +225,6 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		rc = -EAGAIN;
 	}
 
-	unload_nls(nls_codepage);
 	return rc;
 }
 
diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
index 43ad1176dcb9..4794f2cf721a 100644
--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -66,8 +66,6 @@ static struct workqueue_struct *dfscache_wq __read_mostly;
 static int cache_ttl;
 static DEFINE_SPINLOCK(cache_ttl_lock);
 
-static struct nls_table *cache_cp;
-
 /*
  * Number of entries in the cache
  */
@@ -173,14 +171,14 @@ char *dfs_cache_canonical_path(const char *path, const struct nls_table *cp, int
 	if (!path || strlen(path) < 3 || (*path != '\\' && *path != '/'))
 		return ERR_PTR(-EINVAL);
 
-	if (unlikely(strcmp(cp->charset, cache_cp->charset))) {
+	if (unlikely(cp)) {
 		tmp = (char *)cifs_strndup_to_utf16(path, strlen(path), &plen, cp, remap);
 		if (!tmp) {
 			cifs_dbg(VFS, "%s: failed to convert path to utf16\n", __func__);
 			return ERR_PTR(-EINVAL);
 		}
 
-		npath = cifs_strndup_from_utf16(tmp, plen, true, cache_cp);
+		npath = cifs_strndup_from_utf16(tmp, plen, true, NULL);
 		kfree(tmp);
 
 		if (!npath) {
@@ -392,9 +390,6 @@ int dfs_cache_init(void)
 		INIT_HLIST_HEAD(&cache_htable[i]);
 
 	atomic_set(&cache_count, 0);
-	cache_cp = load_nls("utf8");
-	if (!cache_cp)
-		cache_cp = load_nls_default();
 
 	cifs_dbg(FYI, "%s: initialized DFS referral cache\n", __func__);
 	return 0;
@@ -408,11 +403,11 @@ static int cache_entry_hash(const void *data, int size, unsigned int *hash)
 {
 	int i, clen;
 	const unsigned char *s = data;
-	wchar_t c;
+	unicode_t c;
 	unsigned int h = 0;
 
 	for (i = 0; i < size; i += clen) {
-		clen = cache_cp->char2uni(&s[i], size - i, &c);
+		clen = utf8_to_utf32(&s[i], size - i, &c);
 		if (unlikely(clen < 0)) {
 			cifs_dbg(VFS, "%s: can't convert char\n", __func__);
 			return clen;
@@ -601,14 +596,14 @@ static int add_cache_entry_locked(struct dfs_info3_param *refs, int numrefs)
 static bool dfs_path_equal(const char *s1, int len1, const char *s2, int len2)
 {
 	int i, l1, l2;
-	wchar_t c1, c2;
+	unicode_t c1, c2;
 
 	if (len1 != len2)
 		return false;
 
 	for (i = 0; i < len1; i += l1) {
-		l1 = cache_cp->char2uni(&s1[i], len1 - i, &c1);
-		l2 = cache_cp->char2uni(&s2[i], len2 - i, &c2);
+		l1 = utf8_to_utf32(&s1[i], len1 - i, &c1);
+		l2 = utf8_to_utf32(&s2[i], len2 - i, &c2);
 		if (unlikely(l1 < 0 && l2 < 0)) {
 			if (s1[i] != s2[i])
 				return false;
@@ -698,7 +693,6 @@ static struct cache_entry *lookup_cache_entry(const char *path)
 void dfs_cache_destroy(void)
 {
 	cancel_delayed_work_sync(&refresh_task);
-	unload_nls(cache_cp);
 	free_mount_group_list();
 	flush_cache_ents();
 	kmem_cache_destroy(cache_slab);
@@ -744,11 +738,9 @@ static int get_dfs_referral(const unsigned int xid, struct cifs_ses *ses, const
 
 	if (!ses || !ses->server || !ses->server->ops->get_dfs_refer)
 		return -EOPNOTSUPP;
-	if (unlikely(!cache_cp))
-		return -EINVAL;
 
 	cifs_dbg(FYI, "%s: ipc=%s referral=%s\n", __func__, ses->tcon_ipc->tree_name, path);
-	rc =  ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs, cache_cp,
+	rc =  ses->server->ops->get_dfs_refer(xid, ses, path, refs, numrefs, NULL,
 					      NO_MAP_UNI_RSVD);
 	if (!rc) {
 		struct dfs_info3_param *ref = *refs;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index a5695748a89b..3dc69787ae17 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -144,7 +144,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	       struct TCP_Server_Info *server)
 {
 	int rc = 0;
-	struct nls_table *nls_codepage;
 	struct cifs_ses *ses;
 	int retries;
 
@@ -250,8 +249,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		 tcon->ses->chans_need_reconnect,
 		 tcon->need_reconnect);
 
-	nls_codepage = load_nls_default();
-
 	/*
 	 * Recheck after acquire mutex. If another thread is negotiating
 	 * and the server never sends an answer the socket will be closed
@@ -284,7 +281,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	mutex_lock(&ses->session_mutex);
 	rc = cifs_negotiate_protocol(0, ses, server);
 	if (!rc) {
-		rc = cifs_setup_session(0, ses, server, nls_codepage);
+		rc = cifs_setup_session(0, ses, server, NULL);
 		if ((rc == -EACCES) && !tcon->retry) {
 			mutex_unlock(&ses->session_mutex);
 			rc = -EHOSTDOWN;
@@ -309,7 +306,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	if (tcon->use_persistent)
 		tcon->need_reopen_files = true;
 
-	rc = cifs_tree_connect(0, tcon, nls_codepage);
+	rc = cifs_tree_connect(0, tcon, NULL);
 	mutex_unlock(&ses->session_mutex);
 
 	cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);
@@ -345,7 +342,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		rc = -EAGAIN;
 	}
 failed:
-	unload_nls(nls_codepage);
 	return rc;
 }
 
@@ -503,12 +499,10 @@ build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt)
 static unsigned int
 build_netname_ctxt(struct smb2_netname_neg_context *pneg_ctxt, char *hostname)
 {
-	struct nls_table *cp = load_nls_default();
-
 	pneg_ctxt->ContextType = SMB2_NETNAME_NEGOTIATE_CONTEXT_ID;
 
 	/* copy up to max of first 100 bytes of server name to NetName field */
-	pneg_ctxt->DataLength = cpu_to_le16(2 * cifs_strtoUTF16(pneg_ctxt->NetName, hostname, 100, cp));
+	pneg_ctxt->DataLength = cpu_to_le16(2 * cifs_strtoUTF16(pneg_ctxt->NetName, hostname, 100, NULL));
 	/* context size is DataLength + minimal smb2_neg_context */
 	return ALIGN(le16_to_cpu(pneg_ctxt->DataLength) + sizeof(struct smb2_neg_context), 8);
 }
@@ -2568,7 +2562,6 @@ alloc_path_with_tree_prefix(__le16 **out_path, int *out_size, int *out_len,
 			    const char *treename, const __le16 *path)
 {
 	int treename_len, path_len;
-	struct nls_table *cp;
 	const __le16 sep[] = {cpu_to_le16('\\'), cpu_to_le16(0x0000)};
 
 	/*
@@ -2595,8 +2588,7 @@ alloc_path_with_tree_prefix(__le16 **out_path, int *out_size, int *out_len,
 	if (!*out_path)
 		return -ENOMEM;
 
-	cp = load_nls_default();
-	cifs_strtoUTF16(*out_path, treename, treename_len, cp);
+	cifs_strtoUTF16(*out_path, treename, treename_len, NULL);
 
 	/* Do not append the separator if the path is empty */
 	if (path[0] != cpu_to_le16(0x0000)) {
@@ -2604,8 +2596,6 @@ alloc_path_with_tree_prefix(__le16 **out_path, int *out_size, int *out_len,
 		UniStrcat(*out_path, path);
 	}
 
-	unload_nls(cp);
-
 	return 0;
 }
 
-- 
2.20.1