After the FUSE daemon crashes, the fuse mount point becomes inaccessible. In some production environments, a watchdog daemon is used to preserve the FUSE connection's file descriptor (fd). When the FUSE daemon crashes, a new FUSE daemon is started and takes over the fd from the watchdog daemon, allowing it to continue providing services. However, if any inflight requests are lost during the crash, the user process becomes stuck as it does not receive any replies. To resolve this issue, this patchset introduces a new notification type that enable resending these pending requests to the FUSE daemon again, allowing the stuck user process to recover. When using the resend API, FUSE daemon needs to ensure avoidance of processing duplicate non-idempotent requests to prevent potential consistency issues. The high bit of the fuse request id is utilized for indicating the resend request. --- v2->v3: - use notification instead of sysfs API to trigger resend - simplify FUSE_REQ_ID_MASK related code - rename some related macro names v1->v2: - remove flush sysfs API in the original mail - add using high bit of request ID for indicating resend requests - add wakeup in fuse_resend_pqueue() Zhao Chen (2): fuse: Introduce a new notification type for resend pending requests fuse: Use the high bit of request ID for indicating resend requests fs/fuse/dev.c | 69 ++++++++++++++++++++++++++++++++++++++- fs/fuse/inode.c | 3 +- include/uapi/linux/fuse.h | 12 +++++++ 3 files changed, 82 insertions(+), 2 deletions(-) -- 2.32.0.3.g01195cf9f
