Userspace generally expects APIs that return -EMSGSIZE to allow for them to adjust their buffer size and retry the operation. However, the fscontext log would previously clear the message even in the -EMSGSIZE case.
Given that it is very cheap for us to check whether the buffer is too small before we remove the message from the ring buffer, let's just do that instead. While we're at it, refactor some fscontext_read() into a separate helper to make the ring buffer logic a bit easier to read.
Fixes: 007ec26cdc9f ("vfs: Implement logging through fs_context") Signed-off-by: Aleksa Sarai cyphar@cyphar.com --- Changes in v3: - selftests: use EXPECT_STREQ() - v2: https://lore.kernel.org/r/20250806-fscontext-log-cleanups-v2-0-88e9d34d142f@cyphar.com
Changes in v2: - Refactor message fetching to fetch_message_locked() which returns ERR_PTR() in error cases. [Al Viro] - v1: https://lore.kernel.org/r/20250806-fscontext-log-cleanups-v1-0-880597d42a5a@cyphar.com
--- Aleksa Sarai (2): fscontext: do not consume log entries when returning -EMSGSIZE selftests/filesystems: add basic fscontext log tests
fs/fsopen.c | 54 +++++----- tools/testing/selftests/filesystems/.gitignore | 1 + tools/testing/selftests/filesystems/Makefile | 2 +- tools/testing/selftests/filesystems/fclog.c | 130 +++++++++++++++++++++++++ 4 files changed, 162 insertions(+), 25 deletions(-) --- base-commit: 66639db858112bf6b0f76677f7517643d586e575 change-id: 20250806-fscontext-log-cleanups-50f0143674ae
Best regards,