linux-ext4 - [PATCH v5 03/13] ext4: move crypt info pointer to fs-specific part of inode

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Message-ID: <20250810075706.172910-4-ebiggers@kernel.org>
Date: Sun, 10 Aug 2025 00:56:56 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: linux-fscrypt@...r.kernel.org,
	fsverity@...ts.linux.dev
Cc: linux-fsdevel@...r.kernel.org,
	linux-ext4@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-mtd@...ts.infradead.org,
	linux-btrfs@...r.kernel.org,
	ceph-devel@...r.kernel.org,
	Christian Brauner <brauner@...nel.org>,
	Eric Biggers <ebiggers@...nel.org>
Subject: [PATCH v5 03/13] ext4: move crypt info pointer to fs-specific part of inode

Move the fscrypt_inode_info pointer into the filesystem-specific part of
the inode by adding the field ext4_inode_info::i_crypt_info and
configuring fscrypt_operations::inode_info_offs accordingly.

This is a prerequisite for a later commit that removes
inode::i_crypt_info, saving memory and improving cache efficiency with
filesystems that don't support fscrypt.

Co-developed-by: Christian Brauner <brauner@...nel.org>
Signed-off-by: Christian Brauner <brauner@...nel.org>
Signed-off-by: Eric Biggers <ebiggers@...nel.org>
---
 fs/ext4/crypto.c | 2 ++
 fs/ext4/ext4.h   | 4 ++++
 fs/ext4/super.c  | 3 +++
 3 files changed, 9 insertions(+)

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index 0a056d97e6402..cf0a0970c0956 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -225,10 +225,12 @@ static bool ext4_has_stable_inodes(struct super_block *sb)
 {
 	return ext4_has_feature_stable_inodes(sb);
 }
 
 const struct fscrypt_operations ext4_cryptops = {
+	.inode_info_offs	= (int)offsetof(struct ext4_inode_info, i_crypt_info) -
+				  (int)offsetof(struct ext4_inode_info, vfs_inode),
 	.needs_bounce_pages	= 1,
 	.has_32bit_inodes	= 1,
 	.supports_subblock_data_units = 1,
 	.legacy_key_prefix	= "ext4:",
 	.get_context		= ext4_get_context,
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 01a6e2de7fc3e..c897109dadb15 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1180,10 +1180,14 @@ struct ext4_inode_info {
 
 	/* Precomputed uuid+inum+igen checksum for seeding inode checksums */
 	__u32 i_csum_seed;
 
 	kprojid_t i_projid;
+
+#ifdef CONFIG_FS_ENCRYPTION
+	struct fscrypt_inode_info *i_crypt_info;
+#endif
 };
 
 /*
  * File system states
  */
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c7d39da7e733b..0c3059ecce37c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1468,10 +1468,13 @@ static void init_once(void *foo)
 	INIT_LIST_HEAD(&ei->i_orphan);
 	init_rwsem(&ei->xattr_sem);
 	init_rwsem(&ei->i_data_sem);
 	inode_init_once(&ei->vfs_inode);
 	ext4_fc_init_inode(&ei->vfs_inode);
+#ifdef CONFIG_FS_ENCRYPTION
+	ei->i_crypt_info = NULL;
+#endif
 }
 
 static int __init init_inodecache(void)
 {
 	ext4_inode_cachep = kmem_cache_create_usercopy("ext4_inode_cache",
-- 
2.50.1