linux-ext4 - [PATCH 07/12] ext4: drop posix acl handlers

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Message-Id: <20230125-fs-acl-remove-generic-xattr-handlers-v1-7-6cf155b492b6@kernel.org>
Date:   Wed, 25 Jan 2023 12:28:52 +0100
From:   Christian Brauner <brauner@...nel.org>
To:     linux-fsdevel@...r.kernel.org, Christoph Hellwig <hch@....de>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Seth Forshee <sforshee@...nel.org>,
        "Christian Brauner (Microsoft)" <brauner@...nel.org>,
        linux-ext4@...r.kernel.org
Subject: [PATCH 07/12] ext4: drop posix acl handlers

Last cycle we introduced a new posix acl api. Filesystems now only need
to implement the inode operations for posix acls. The generic xattr
handlers aren't used anymore by the vfs and will be completely removed.
Keeping the handler around is confusing and gives the false impression
that the xattr infrastructure of the vfs is used to interact with posix
acls when it really isn't anymore.

For this to work we simply rework the ->listxattr() inode operation to
not rely on the generix posix acl handlers anymore.

Cc: <linux-ext4@...r.kernel.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner@...nel.org>
---
 fs/ext4/xattr.c | 71 ++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 40 insertions(+), 31 deletions(-)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 7decaaf27e82..5472b8eac672 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -83,26 +83,9 @@ static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
 				    size_t value_count);
 static void ext4_xattr_rehash(struct ext4_xattr_header *);
 
-static const struct xattr_handler * const ext4_xattr_handler_map[] = {
-	[EXT4_XATTR_INDEX_USER]		     = &ext4_xattr_user_handler,
-#ifdef CONFIG_EXT4_FS_POSIX_ACL
-	[EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
-	[EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
-#endif
-	[EXT4_XATTR_INDEX_TRUSTED]	     = &ext4_xattr_trusted_handler,
-#ifdef CONFIG_EXT4_FS_SECURITY
-	[EXT4_XATTR_INDEX_SECURITY]	     = &ext4_xattr_security_handler,
-#endif
-	[EXT4_XATTR_INDEX_HURD]		     = &ext4_xattr_hurd_handler,
-};
-
 const struct xattr_handler *ext4_xattr_handlers[] = {
 	&ext4_xattr_user_handler,
 	&ext4_xattr_trusted_handler,
-#ifdef CONFIG_EXT4_FS_POSIX_ACL
-	&posix_acl_access_xattr_handler,
-	&posix_acl_default_xattr_handler,
-#endif
 #ifdef CONFIG_EXT4_FS_SECURITY
 	&ext4_xattr_security_handler,
 #endif
@@ -110,6 +93,43 @@ const struct xattr_handler *ext4_xattr_handlers[] = {
 	NULL
 };
 
+static const char *ext4_xattr_prefix(int xattr_index, struct dentry *dentry)
+{
+	const char *name = NULL;
+	const struct xattr_handler *handler = NULL;
+
+	switch (xattr_index) {
+	case EXT4_XATTR_INDEX_USER:
+		handler = &ext4_xattr_user_handler;
+		break;
+	case EXT4_XATTR_INDEX_TRUSTED:
+		handler = &ext4_xattr_trusted_handler;
+		break;
+#ifdef CONFIG_EXT4_FS_SECURITY
+	case EXT4_XATTR_INDEX_SECURITY:
+		handler = &ext4_xattr_security_handler;
+		break;
+#endif
+#ifdef CONFIG_EXT4_FS_POSIX_ACL
+	case EXT4_XATTR_INDEX_POSIX_ACL_ACCESS:
+		if (posix_acl_dentry_list(dentry))
+			name = XATTR_NAME_POSIX_ACL_ACCESS;
+		break;
+	case EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT:
+		if (posix_acl_dentry_list(dentry))
+			name = XATTR_NAME_POSIX_ACL_DEFAULT;
+		break;
+#endif
+	default:
+		return NULL;
+	}
+
+	if (xattr_dentry_list(handler, dentry))
+		name = xattr_prefix(handler);
+
+	return name;
+}
+
 #define EA_BLOCK_CACHE(inode)	(((struct ext4_sb_info *) \
 				inode->i_sb->s_fs_info)->s_ea_block_cache)
 
@@ -171,16 +191,6 @@ static void ext4_xattr_block_csum_set(struct inode *inode,
 						bh->b_blocknr, BHDR(bh));
 }
 
-static inline const struct xattr_handler *
-ext4_xattr_handler(int name_index)
-{
-	const struct xattr_handler *handler = NULL;
-
-	if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
-		handler = ext4_xattr_handler_map[name_index];
-	return handler;
-}
-
 static int
 ext4_xattr_check_entries(struct ext4_xattr_entry *entry, void *end,
 			 void *value_start)
@@ -679,11 +689,10 @@ ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 	size_t rest = buffer_size;
 
 	for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
-		const struct xattr_handler *handler =
-			ext4_xattr_handler(entry->e_name_index);
+		const char *prefix;
 
-		if (handler && (!handler->list || handler->list(dentry))) {
-			const char *prefix = handler->prefix ?: handler->name;
+		prefix = ext4_xattr_prefix(entry->e_name_index, dentry);
+		if (prefix) {
 			size_t prefix_len = strlen(prefix);
 			size_t size = prefix_len + entry->e_name_len + 1;
 

-- 
2.34.1