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);
+}
+
/**
* 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
|