On 8/10/23 11:51, Luís Henriques wrote:
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,
Oof, guess I need to add 'build btrfs as a module' to my preflight checklist. Thank you.
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