On Tue, 2025-07-15 at 16:35 +0200, Christian Brauner wrote:
> struct inode is bloated as everyone is aware and we should try and
> shrink it as that's potentially a lot of memory savings. I've already
> freed up around 8 bytes but we can probably do better.
>
> There's a bunch of stuff that got shoved into struct inode that I don't
> think deserves a spot in there. There are two members I'm currently
> particularly interested in:
>
> (1) #ifdef CONFIG_FS_ENCRYPTION
> struct fscrypt_inode_info *i_crypt_info;
> #endif
>
> ceph, ext4, f2fs, ubifs
>
> (2) #ifdef CONFIG_FS_VERITY
> struct fsverity_info *i_verity_info;
> #endif
>
> btrfs, ext4, f2fs
>
> So we have 4 users for fscrypt and 3 users for fsverity with both
> features having been around for a decent amount of time.
>
> For all other filesystems the 16 bytes are just wasted bloating inodes
> for every pseudo filesystem and most other regular filesystems.
>
> We should be able to move both of these out of struct inode by adding
> inode operations and making it the filesystem's responsibility to
> accommodate the information in their respective inodes.
>
> Unless there are severe performance penalties for the extra pointer
> dereferences getting our hands on 16 bytes is a good reason to at least
> consider doing this.
>
> I've drafted one way of doing this using ext4 as my victim^wexample. I'd
> like to hear some early feedback whether this is something we would want
> to pursue.
>
> Build failures very much expected!
>
> Not-Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
> ---
> fs/crypto/bio.c | 2 +-
> fs/crypto/crypto.c | 8 ++++----
> fs/crypto/fname.c | 8 ++++----
> fs/crypto/fscrypt_private.h | 3 +--
> fs/crypto/hooks.c | 2 +-
> fs/crypto/inline_crypt.c | 10 +++++-----
> fs/crypto/keysetup.c | 21 ++++----------------
> fs/crypto/policy.c | 8 ++++----
> fs/ext4/ext4.h | 9 +++++++++
> fs/ext4/file.c | 4 ++++
> fs/ext4/namei.c | 22 +++++++++++++++++++++
> fs/ext4/super.c | 6 +++++-
> fs/ext4/symlink.c | 12 ++++++++++++
> include/linux/fs.h | 9 +++++----
> include/linux/fscrypt.h | 47 ++++++++++++++++++++++++++++++---------------
> 15 files changed, 112 insertions(+), 59 deletions(-)
>
> diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
> index 0ad8c30b8fa5..f541e6b3a9cc 100644
> --- a/fs/crypto/bio.c
> +++ b/fs/crypto/bio.c
> @@ -111,7 +111,7 @@ static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,
> int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
> sector_t pblk, unsigned int len)
> {
> - const struct fscrypt_inode_info *ci = inode->i_crypt_info;
> + const struct fscrypt_inode_info *ci = inode->i_op->get_fscrypt(inode);
> const unsigned int du_bits = ci->ci_data_unit_bits;
> const unsigned int du_size = 1U << du_bits;
> const unsigned int du_per_page_bits = PAGE_SHIFT - du_bits;
> diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
> index b74b5937e695..c480f6867101 100644
> --- a/fs/crypto/crypto.c
> +++ b/fs/crypto/crypto.c
> @@ -181,7 +181,7 @@ struct page *fscrypt_encrypt_pagecache_blocks(struct folio *folio,
> size_t len, size_t offs, gfp_t gfp_flags)
> {
> const struct inode *inode = folio->mapping->host;
> - const struct fscrypt_inode_info *ci = inode->i_crypt_info;
> + const struct fscrypt_inode_info *ci = inode->i_op->get_fscrypt(inode);
> const unsigned int du_bits = ci->ci_data_unit_bits;
> const unsigned int du_size = 1U << du_bits;
> struct page *ciphertext_page;
> @@ -241,7 +241,7 @@ int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
> {
> if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))
> return -EOPNOTSUPP;
> - return fscrypt_crypt_data_unit(inode->i_crypt_info, FS_ENCRYPT,
> + return fscrypt_crypt_data_unit(inode->i_op->get_fscrypt(inode), FS_ENCRYPT,
> lblk_num, page, page, len, offs,
> gfp_flags);
> }
> @@ -265,7 +265,7 @@ int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len,
> size_t offs)
> {
> const struct inode *inode = folio->mapping->host;
> - const struct fscrypt_inode_info *ci = inode->i_crypt_info;
> + const struct fscrypt_inode_info *ci = inode->i_op->get_fscrypt(inode);
> const unsigned int du_bits = ci->ci_data_unit_bits;
> const unsigned int du_size = 1U << du_bits;
> u64 index = ((u64)folio->index << (PAGE_SHIFT - du_bits)) +
> @@ -316,7 +316,7 @@ int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
> {
> if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))
> return -EOPNOTSUPP;
> - return fscrypt_crypt_data_unit(inode->i_crypt_info, FS_DECRYPT,
> + return fscrypt_crypt_data_unit(inode->i_op->get_fscrypt(inode), FS_DECRYPT,
> lblk_num, page, page, len, offs,
> GFP_NOFS);
> }
> diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
> index 010f9c0a4c2f..a0317df113a9 100644
> --- a/fs/crypto/fname.c
> +++ b/fs/crypto/fname.c
> @@ -94,7 +94,7 @@ int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
> {
> struct skcipher_request *req = NULL;
> DECLARE_CRYPTO_WAIT(wait);
> - const struct fscrypt_inode_info *ci = inode->i_crypt_info;
> + const struct fscrypt_inode_info *ci = inode->i_op->get_fscrypt(inode);
> struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
> union fscrypt_iv iv;
> struct scatterlist sg;
> @@ -151,7 +151,7 @@ static int fname_decrypt(const struct inode *inode,
> struct skcipher_request *req = NULL;
> DECLARE_CRYPTO_WAIT(wait);
> struct scatterlist src_sg, dst_sg;
> - const struct fscrypt_inode_info *ci = inode->i_crypt_info;
> + const struct fscrypt_inode_info *ci = inode->i_op->get_fscrypt(inode);
> struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
> union fscrypt_iv iv;
> int res;
> @@ -293,7 +293,7 @@ bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
> bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
> u32 max_len, u32 *encrypted_len_ret)
> {
> - return __fscrypt_fname_encrypted_size(&inode->i_crypt_info->ci_policy,
> + return __fscrypt_fname_encrypted_size(&inode->i_op->get_fscrypt(inode)->ci_policy,
> orig_len, max_len,
> encrypted_len_ret);
> }
> @@ -562,7 +562,7 @@ EXPORT_SYMBOL_GPL(fscrypt_match_name);
> */
> u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name)
> {
> - const struct fscrypt_inode_info *ci = dir->i_crypt_info;
> + const struct fscrypt_inode_info *ci = dir->i_op->get_fscrypt(dir);
>
> WARN_ON_ONCE(!ci->ci_dirhash_key_initialized);
>
> diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
> index c1d92074b65c..ddc3c86494cf 100644
> --- a/fs/crypto/fscrypt_private.h
> +++ b/fs/crypto/fscrypt_private.h
> @@ -231,8 +231,7 @@ struct fscrypt_prepared_key {
> * fscrypt_inode_info - the "encryption key" for an inode
> *
> * When an encrypted file's key is made available, an instance of this struct is
> - * allocated and stored in ->i_crypt_info. Once created, it remains until the
> - * inode is evicted.
> + * allocated and stored. Once created, it remains until the inode is evicted.
> */
> struct fscrypt_inode_info {
>
> diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
> index d8d5049b8fe1..a45763da352e 100644
> --- a/fs/crypto/hooks.c
> +++ b/fs/crypto/hooks.c
> @@ -197,7 +197,7 @@ int fscrypt_prepare_setflags(struct inode *inode,
> err = fscrypt_require_key(inode);
> if (err)
> return err;
> - ci = inode->i_crypt_info;
> + ci = inode->i_op->get_fscrypt(inode);
> if (ci->ci_policy.version != FSCRYPT_POLICY_V2)
> return -EINVAL;
> mk = ci->ci_master_key;
> diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
> index 1d008c440cb6..f5a6560a9c2e 100644
> --- a/fs/crypto/inline_crypt.c
> +++ b/fs/crypto/inline_crypt.c
> @@ -262,7 +262,7 @@ int fscrypt_derive_sw_secret(struct super_block *sb,
>
> bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
> {
> - return inode->i_crypt_info->ci_inlinecrypt;
> + return inode->i_op->get_fscrypt(inode)->ci_inlinecrypt;
> }
> EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto);
>
> @@ -306,7 +306,7 @@ void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode,
>
> if (!fscrypt_inode_uses_inline_crypto(inode))
> return;
> - ci = inode->i_crypt_info;
> + ci = inode->i_op->get_fscrypt(inode);
>
> fscrypt_generate_dun(ci, first_lblk, dun);
> bio_crypt_set_ctx(bio, ci->ci_enc_key.blk_key, dun, gfp_mask);
> @@ -396,10 +396,10 @@ bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
> * uses the same pointer. I.e., there's currently no need to support
> * merging requests where the keys are the same but the pointers differ.
> */
> - if (bc->bc_key != inode->i_crypt_info->ci_enc_key.blk_key)
> + if (bc->bc_key != inode->i_op->get_fscrypt(inode)->ci_enc_key.blk_key)
> return false;
>
> - fscrypt_generate_dun(inode->i_crypt_info, next_lblk, next_dun);
> + fscrypt_generate_dun(inode->i_op->get_fscrypt(inode), next_lblk, next_dun);
> return bio_crypt_dun_is_contiguous(bc, bio->bi_iter.bi_size, next_dun);
> }
> EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio);
> @@ -501,7 +501,7 @@ u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks)
> if (nr_blocks <= 1)
> return nr_blocks;
>
> - ci = inode->i_crypt_info;
> + ci = inode->i_op->get_fscrypt(inode);
> if (!(fscrypt_policy_flags(&ci->ci_policy) &
> FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32))
> return nr_blocks;
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index 0d71843af946..90e1ea83c573 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -568,7 +568,7 @@ static int setup_file_encryption_key(struct fscrypt_inode_info *ci,
> return err;
> }
>
> -static void put_crypt_info(struct fscrypt_inode_info *ci)
> +void put_crypt_info(struct fscrypt_inode_info *ci)
> {
> struct fscrypt_master_key *mk;
>
> @@ -597,6 +597,7 @@ static void put_crypt_info(struct fscrypt_inode_info *ci)
> memzero_explicit(ci, sizeof(*ci));
> kmem_cache_free(fscrypt_inode_info_cachep, ci);
> }
> +EXPORT_SYMBOL(put_crypt_info);
>
> static int
> fscrypt_setup_encryption_info(struct inode *inode,
> @@ -644,7 +645,7 @@ fscrypt_setup_encryption_info(struct inode *inode,
> * fscrypt_get_inode_info(). I.e., here we publish ->i_crypt_info with
> * a RELEASE barrier so that other tasks can ACQUIRE it.
> */
> - if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) {
> + if (!inode->i_op->set_fscrypt(crypt_info, inode)) {
> /*
> * We won the race and set ->i_crypt_info to our crypt_info.
> * Now link it into the master key's inode list.
> @@ -788,20 +789,6 @@ int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
> }
> EXPORT_SYMBOL_GPL(fscrypt_prepare_new_inode);
>
> -/**
> - * fscrypt_put_encryption_info() - free most of an inode's fscrypt data
> - * @inode: an inode being evicted
> - *
> - * Free the inode's fscrypt_inode_info. Filesystems must call this when the
> - * inode is being evicted. An RCU grace period need not have elapsed yet.
> - */
> -void fscrypt_put_encryption_info(struct inode *inode)
> -{
> - put_crypt_info(inode->i_crypt_info);
> - inode->i_crypt_info = NULL;
> -}
> -EXPORT_SYMBOL(fscrypt_put_encryption_info);
> -
> /**
> * fscrypt_free_inode() - free an inode's fscrypt data requiring RCU delay
> * @inode: an inode being freed
> @@ -830,7 +817,7 @@ EXPORT_SYMBOL(fscrypt_free_inode);
> */
> int fscrypt_drop_inode(struct inode *inode)
> {
> - const struct fscrypt_inode_info *ci = fscrypt_get_inode_info(inode);
> + const struct fscrypt_inode_info *ci = inode->i_op->get_fscrypt(inode);
>
> /*
> * If ci is NULL, then the inode doesn't have an encryption key set up
> diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
> index 701259991277..694d1ed26eeb 100644
> --- a/fs/crypto/policy.c
> +++ b/fs/crypto/policy.c
> @@ -436,7 +436,7 @@ static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy)
> union fscrypt_context ctx;
> int ret;
>
> - ci = fscrypt_get_inode_info(inode);
> + ci = inode->i_op->get_fscrypt(inode);
> if (ci) {
> /* key available, use the cached policy */
> *policy = ci->ci_policy;
> @@ -725,7 +725,7 @@ const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir)
> err = fscrypt_require_key(dir);
> if (err)
> return ERR_PTR(err);
> - return &dir->i_crypt_info->ci_policy;
> + return &dir->i_op->get_fscrypt(dir)->ci_policy;
> }
>
> return fscrypt_get_dummy_policy(dir->i_sb);
> @@ -744,7 +744,7 @@ const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir)
> */
> int fscrypt_context_for_new_inode(void *ctx, struct inode *inode)
> {
> - struct fscrypt_inode_info *ci = inode->i_crypt_info;
> + struct fscrypt_inode_info *ci = inode->i_op->get_fscrypt(inode);
>
> BUILD_BUG_ON(sizeof(union fscrypt_context) !=
> FSCRYPT_SET_CONTEXT_MAX_SIZE);
> @@ -769,7 +769,7 @@ EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode);
> */
> int fscrypt_set_context(struct inode *inode, void *fs_data)
> {
> - struct fscrypt_inode_info *ci = inode->i_crypt_info;
> + struct fscrypt_inode_info *ci = inode->i_op->get_fscrypt(inode);
> union fscrypt_context ctx;
> int ctxsize;
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 18373de980f2..34685eec6245 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1197,6 +1197,10 @@ struct ext4_inode_info {
> __u32 i_csum_seed;
>
> kprojid_t i_projid;
> +
> +#ifdef CONFIG_FS_ENCRYPTION
> + struct fscrypt_inode_info *i_fscrypt_info;
> +#endif
> };
>
> /*
> @@ -3904,6 +3908,11 @@ static inline bool ext4_inode_can_atomic_write(struct inode *inode)
> extern int ext4_block_write_begin(handle_t *handle, struct folio *folio,
> loff_t pos, unsigned len,
> get_block_t *get_block);
> +#ifdef CONFIG_FS_ENCRYPTION
> +struct fscrypt_inode_info *ext4_get_fscrypt(const struct inode *inode);
> +int ext4_set_fscrypt(struct fscrypt_inode_info *fscrypt_info,struct inode *inode);
> +#endif
> +
> #endif /* __KERNEL__ */
>
> #define EFSBADCRC EBADMSG /* Bad CRC detected */
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 21df81347147..676d33a7d842 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -989,5 +989,9 @@ const struct inode_operations ext4_file_inode_operations = {
> .fiemap = ext4_fiemap,
> .fileattr_get = ext4_fileattr_get,
> .fileattr_set = ext4_fileattr_set,
> +#ifdef CONFIG_FS_ENCRYPTION
> + .get_fscrypt = ext4_get_fscrypt,
> + .set_fscrypt = ext4_set_fscrypt,
> +#endif
> };
>
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index a178ac229489..a27c5925c836 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -4203,6 +4203,20 @@ static int ext4_rename2(struct mnt_idmap *idmap,
> return ext4_rename(idmap, old_dir, old_dentry, new_dir, new_dentry, flags);
> }
>
> +#ifdef CONFIG_FS_ENCRYPTION
> +struct fscrypt_inode_info *ext4_get_fscrypt(const struct inode *inode)
> +{
> + struct ext4_inode_info *ei = EXT4_I(inode);
> + return fscrypt_inode_info_get(&ei->i_fscrypt_info);
> +}
> +
> +int ext4_set_fscrypt(struct fscrypt_inode_info *fscrypt_info, struct inode *inode)
> +{
> + struct ext4_inode_info *ei = EXT4_I(inode);
> + return fscrypt_inode_info_set(fscrypt_info, &ei->i_fscrypt_info);
> +}
> +#endif
> +
> /*
> * directories can handle most operations...
> */
> @@ -4225,6 +4239,10 @@ const struct inode_operations ext4_dir_inode_operations = {
> .fiemap = ext4_fiemap,
> .fileattr_get = ext4_fileattr_get,
> .fileattr_set = ext4_fileattr_set,
> +#ifdef CONFIG_FS_ENCRYPTION
> + .get_fscrypt = ext4_get_fscrypt,
> + .set_fscrypt = ext4_set_fscrypt,
> +#endif
> };
>
> const struct inode_operations ext4_special_inode_operations = {
> @@ -4233,4 +4251,8 @@ const struct inode_operations ext4_special_inode_operations = {
> .listxattr = ext4_listxattr,
> .get_inode_acl = ext4_get_acl,
> .set_acl = ext4_set_acl,
> +#ifdef CONFIG_FS_ENCRYPTION
> + .get_fscrypt = ext4_get_fscrypt,
> + .set_fscrypt = ext4_set_fscrypt,
> +#endif
> };
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index c7d39da7e733..972b057b0d00 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1412,6 +1412,9 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
> INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
> ext4_fc_init_inode(&ei->vfs_inode);
> spin_lock_init(&ei->i_fc_lock);
> +#ifdef CONFIG_FS_ENCRYPTION
> + ei->i_fscrypt_info = NULL;
> +#endif
> return &ei->vfs_inode;
> }
>
> @@ -1509,7 +1512,8 @@ void ext4_clear_inode(struct inode *inode)
> jbd2_free_inode(EXT4_I(inode)->jinode);
> EXT4_I(inode)->jinode = NULL;
> }
> - fscrypt_put_encryption_info(inode);
> + put_crypt_info(EXT4_I(inode)->i_fscrypt_info);
> + EXT4_I(inode)->i_fscrypt_info = NULL;
> fsverity_cleanup_inode(inode);
> }
>
> diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c
> index 645240cc0229..ee3f71e406ce 100644
> --- a/fs/ext4/symlink.c
> +++ b/fs/ext4/symlink.c
> @@ -119,6 +119,10 @@ const struct inode_operations ext4_encrypted_symlink_inode_operations = {
> .setattr = ext4_setattr,
> .getattr = ext4_encrypted_symlink_getattr,
> .listxattr = ext4_listxattr,
> +#ifdef CONFIG_FS_ENCRYPTION
> + .get_fscrypt = ext4_get_fscrypt,
> + .set_fscrypt = ext4_set_fscrypt,
> +#endif
> };
>
> const struct inode_operations ext4_symlink_inode_operations = {
> @@ -126,6 +130,10 @@ const struct inode_operations ext4_symlink_inode_operations = {
> .setattr = ext4_setattr,
> .getattr = ext4_getattr,
> .listxattr = ext4_listxattr,
> +#ifdef CONFIG_FS_ENCRYPTION
> + .get_fscrypt = ext4_get_fscrypt,
> + .set_fscrypt = ext4_set_fscrypt,
> +#endif
> };
>
> const struct inode_operations ext4_fast_symlink_inode_operations = {
> @@ -133,4 +141,8 @@ const struct inode_operations ext4_fast_symlink_inode_operations = {
> .setattr = ext4_setattr,
> .getattr = ext4_getattr,
> .listxattr = ext4_listxattr,
> +#ifdef CONFIG_FS_ENCRYPTION
> + .get_fscrypt = ext4_get_fscrypt,
> + .set_fscrypt = ext4_set_fscrypt,
> +#endif
> };
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 96c7925a6551..600b878f41ab 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -778,10 +778,6 @@ struct inode {
> struct fsnotify_mark_connector __rcu *i_fsnotify_marks;
> #endif
>
> -#ifdef CONFIG_FS_ENCRYPTION
> - struct fscrypt_inode_info *i_crypt_info;
> -#endif
> -
> #ifdef CONFIG_FS_VERITY
> struct fsverity_info *i_verity_info;
> #endif
> @@ -2257,6 +2253,11 @@ struct inode_operations {
> struct dentry *dentry, struct fileattr *fa);
> int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);
> struct offset_ctx *(*get_offset_ctx)(struct inode *inode);
> +#ifdef CONFIG_FS_ENCRYPTION
> + struct fscrypt_inode_info *(*get_fscrypt)(const struct inode *inode);
> + int (*set_fscrypt)(struct fscrypt_inode_info *fscrypt_info,
> + struct inode *inode);
> +#endif
> } ____cacheline_aligned;
>
> /* Did the driver provide valid mmap hook configuration? */
> diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
> index 56fad33043d5..7ac612fec6bb 100644
> --- a/include/linux/fscrypt.h
> +++ b/include/linux/fscrypt.h
> @@ -195,18 +195,6 @@ struct fscrypt_operations {
> int fscrypt_d_revalidate(struct inode *dir, const struct qstr *name,
> struct dentry *dentry, unsigned int flags);
>
> -static inline struct fscrypt_inode_info *
> -fscrypt_get_inode_info(const struct inode *inode)
> -{
> - /*
> - * Pairs with the cmpxchg_release() in fscrypt_setup_encryption_info().
> - * I.e., another task may publish ->i_crypt_info concurrently, executing
> - * a RELEASE barrier. We need to use smp_load_acquire() here to safely
> - * ACQUIRE the memory the other task published.
> - */
> - return smp_load_acquire(&inode->i_crypt_info);
> -}
> -
> /**
> * fscrypt_needs_contents_encryption() - check whether an inode needs
> * contents encryption
> @@ -385,7 +373,7 @@ int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
> /* keysetup.c */
> int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
> bool *encrypt_ret);
> -void fscrypt_put_encryption_info(struct inode *inode);
> +void put_crypt_info(struct fscrypt_inode_info *ci);
> void fscrypt_free_inode(struct inode *inode);
> int fscrypt_drop_inode(struct inode *inode);
>
> @@ -446,10 +434,37 @@ static inline void fscrypt_set_ops(struct super_block *sb,
> {
> sb->s_cop = s_cop;
> }
> +
> +static inline int fscrypt_inode_info_set(struct fscrypt_inode_info *crypt_info,
> + struct fscrypt_inode_info **p)
> +{
> + if (cmpxchg_release(p, NULL, crypt_info) != NULL)
> + return -EEXIST;
> + return 0;
> +}
> +
> +static inline struct fscrypt_inode_info *
> +fscrypt_inode_info_get(struct fscrypt_inode_info **crypt_info)
> +{
> + /*
> + * Pairs with the cmpxchg_release() in fscrypt_inode_info_set(). I.e.,
> + * another task may publish crypt_info concurrently, executing a
> + * RELEASE barrier. We need to use smp_load_acquire() here to safely
> + * ACQUIRE the memory the other task published (could be a READ_ONCE()
> + * really).
> + */
> + return smp_load_acquire(crypt_info);
> +}
> #else /* !CONFIG_FS_ENCRYPTION */
>
> +static inline int fscrypt_inode_info_set(struct fscrypt_inode_info *crypt_info,
> + struct fscrypt_inode_info **p)
> +{
> + return 0;
> +}
> +
> static inline struct fscrypt_inode_info *
> -fscrypt_get_inode_info(const struct inode *inode)
> +fscrypt_inode_info_get(const struct fscrypt_inode_info **crypt_info)
> {
> return NULL;
> }
> @@ -639,7 +654,7 @@ static inline int fscrypt_prepare_new_inode(struct inode *dir,
> return 0;
> }
>
> -static inline void fscrypt_put_encryption_info(struct inode *inode)
> +static inline void put_crypt_info(struct fscrypt_inode_info *ci)
> {
> return;
> }
> @@ -930,7 +945,7 @@ static inline bool fscrypt_inode_uses_fs_layer_crypto(const struct inode *inode)
> */
> static inline bool fscrypt_has_encryption_key(const struct inode *inode)
> {
> - return fscrypt_get_inode_info(inode) != NULL;
> + return inode->i_op->get_fscrypt(inode) != NULL;
> }
>
> /**
>
> ---
> base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494
> change-id: 20250715-work-inode-fscrypt-2b63b276e793
I like the concept. Debloating struct inode is a great goal, IMO.
Fields that are not generally useful should be in the fs-specific
inodes.
I do wish it weren't quite so cumbersome with having to define
_get/_set operations, but I think it's a reasonable tradeoff to get
these fields out of struct inode.
Cheers!
--
Jeff Layton <jlayton@xxxxxxxxxx>
