Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx> writes:
> btrfs occasionally splits in-memory extents while holding a mutex. This
> means we can't just copy the info, since setting up a new inlinecrypt
> key requires taking a semaphore. Thus adding a mechanism to split
> extents and merely take a new reference on the info is necessary.
>
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx>
> ---
> fs/crypto/fscrypt_private.h | 5 +++++
> fs/crypto/keysetup.c | 18 +++++++++++++++++-
> include/linux/fscrypt.h | 2 ++
> 3 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
> index cd29c71b4349..03be2c136c0e 100644
> --- a/fs/crypto/fscrypt_private.h
> +++ b/fs/crypto/fscrypt_private.h
> @@ -287,6 +287,11 @@ struct fscrypt_info {
>
> /* Hashed inode number. Only set for IV_INO_LBLK_32 */
> u32 ci_hashed_ino;
> +
> + /* Reference count. Normally 1, unless a extent info is shared by
> + * several virtual extents.
> + */
> + refcount_t refs;
> };
>
> typedef enum {
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index 8d50716bdf11..12c3851b7cd6 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -598,7 +598,7 @@ static void put_crypt_info(struct fscrypt_info *ci)
> {
> struct fscrypt_master_key *mk;
>
> - if (!ci)
> + if (!ci || !refcount_dec_and_test(&ci->refs))
> return;
>
> if (ci->ci_enc_key) {
> @@ -686,6 +686,7 @@ fscrypt_setup_encryption_info(struct inode *inode,
> crypt_info->ci_inode = inode;
> crypt_info->ci_sb = inode->i_sb;
> crypt_info->ci_policy = *policy;
> + refcount_set(&crypt_info->refs, 1);
> memcpy(crypt_info->ci_nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);
>
> mode = select_encryption_mode(&crypt_info->ci_policy, inode);
> @@ -1046,6 +1047,21 @@ int fscrypt_load_extent_info(struct inode *inode, void *buf, size_t len,
> }
> EXPORT_SYMBOL_GPL(fscrypt_load_extent_info);
>
> +/**
> + * fscrypt_get_extent_info_ref() - mark a second extent using the same info
> + * @info: the info to be used by another extent
> + *
> + * Sometimes, an existing extent must be split into multiple extents in memory.
> + * In such a case, this function allows multiple extents to use the same extent
> + * info without allocating or taking any lock, which is necessary in certain IO
> + * paths.
> + */
> +void fscrypt_get_extent_info_ref(struct fscrypt_info *info)
> +{
> + if (info)
> + refcount_inc(&info->refs);
> +}
> +
There's an EXPORT_SYMBOL_GPL() missing here, right?
Cheers,
--
Luís
>
> /**
> * fscrypt_put_encryption_info() - free most of an inode's fscrypt data
> * @inode: an inode being evicted
> diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
> index 4ba624beea91..b67054a2c965 100644
> --- a/include/linux/fscrypt.h
> +++ b/include/linux/fscrypt.h
> @@ -370,6 +370,8 @@ void fscrypt_free_extent_info(struct fscrypt_info **info_ptr);
> int fscrypt_load_extent_info(struct inode *inode, void *buf, size_t len,
> struct fscrypt_info **info_ptr);
>
> +void fscrypt_get_extent_info_ref(struct fscrypt_info *info);
> +
> /* fname.c */
> int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
> u8 *out, unsigned int olen);
> --
>
> 2.41.0
>
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