[PATCH v4 0/2] fuse: add timeout option for requests

[Joanne Koong <joannelkoong@gmail.com>]

There are situations where fuse servers can become unresponsive or take
too long to reply to a request. Currently there is no upper bound on
how long a request may take, which may be frustrating to users who get
stuck waiting for a request to complete.

This patchset adds a timeout option for requests and two dynamically
configurable fuse sysctls "default_request_timeout" and "max_request_timeout"
for controlling/enforcing timeout behavior system-wide.

Existing fuse servers will not be affected unless they explicitly opt into the
timeout.

v3: https://lore.kernel.org/linux-fsdevel/20240808190110.3188039-1-joannelkoong@gmail.com/
Changes from v3 -> v4:
- Fix wording on some comments to make it more clear
- Use simpler logic for timer (eg remove extra if checks, use mod timer API) (Josef)
- Sanity-check should be on FR_FINISHING not FR_FINISHED (Jingbo)
- Fix comment for "processing queue", add req->fpq = NULL safeguard  (Bernd)

v2: https://lore.kernel.org/linux-fsdevel/20240730002348.3431931-1-joannelkoong@gmail.com/
Changes from v2 -> v3:
- Disarm / rearm timer in dev_do_read to handle race conditions (Bernrd)
- Disarm timer in error handling for fatal interrupt (Yafang)
- Clean up do_fuse_request_end (Jingbo)
- Add timer for notify retrieve requests 
- Fix kernel test robot errors for #define no-op functions

v1: https://lore.kernel.org/linux-fsdevel/20240717213458.1613347-1-joannelkoong@gmail.com/
Changes from v1 -> v2:
- Add timeout for background requests
- Handle resend race condition
- Add sysctls

Joanne Koong (2):
  fuse: add optional kernel-enforced timeout for requests
  fuse: add default_request_timeout and max_request_timeout sysctls

 Documentation/admin-guide/sysctl/fs.rst |  17 +++
 fs/fuse/Makefile                        |   2 +-
 fs/fuse/dev.c                           | 192 +++++++++++++++++++++++-
 fs/fuse/fuse_i.h                        |  30 ++++
 fs/fuse/inode.c                         |  24 +++
 fs/fuse/sysctl.c                        |  42 ++++++
 6 files changed, 298 insertions(+), 9 deletions(-)
 create mode 100644 fs/fuse/sysctl.c

-- 
2.43.5