Hello Linus,
could you please pull from
git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git fsnotify_hsm_for_v6.14-rc1
to get support for fsnotify pre-content (or HSM) event. Let me quickly sum
up what the feature is about:
The patches introduce new fsnotify event (FS_PRE_ACCESS) that gets
generated before a file contents is accessed. The event is synchronous so
if there is listener for this event, the kernel waits for reply. On success
the execution continues as usual, on failure we propagate the error to
userspace. This allows userspace to fill in file content on demand from
slow storage. The context in which the events are generated has been
picked so that we don't hold any locks and thus there's no risk of a
deadlock for the userspace handler.
The new pre-content event is available only for users with global
CAP_SYS_ADMIN capability (similarly to other parts of fanotify
functionality) and it is an administrator responsibility to make sure the
userspace event handler doesn't do stupid stuff that can DoS the system.
Based on your feedback from the last submission, fsnotify code has been
improved and now file->f_mode encodes whether pre-content event needs to be
generated for the file so the fast path when nobody wants pre-content event
for the file just grows the additional file->f_mode check. As a bonus this
also removes the checks whether the old FS_ACCESS event needs to be
generated from the fast path. Also the place where the event is generated
during page fault has been moved so now filemap_fault() generates the event
if and only if there is no uptodate folio in the page cache.
Also we have dropped FS_PRE_MODIFY event as current real-world users of the
pre-content functionality don't really use it so let's start with the
minimal useful feature set.
Top of the tree is 0c0214df28f0. The full shortlog is:
Al Viro (1):
fs: get rid of __FMODE_NONOTIFY kludge
Amir Goldstein (11):
fsnotify: opt-in for permission events at file open time
fsnotify: check if file is actually being watched for pre-content events on open
fanotify: rename a misnamed constant
fanotify: reserve event bit of deprecated FAN_DIR_MODIFY
fsnotify: introduce pre-content permission events
fsnotify: pass optional file access range in pre-content event
fsnotify: generate pre-content permission event on truncate
fanotify: introduce FAN_PRE_ACCESS permission event
fanotify: report file range info with pre-content events
fanotify: allow to set errno in FAN_DENY permission response
fs: don't block write during exec on pre-content watched files
Jan Kara (2):
ext4: add pre-content fsnotify hook for DAX faults
fanotify: Fix crash in fanotify_init(2)
Josef Bacik (7):
fanotify: don't skip extra event info if no info_mode is set
fanotify: disable readahead if we have pre-content watches
mm: don't allow huge faults for files with pre content watches
fsnotify: generate pre-content permission event on page fault
xfs: add pre-content fsnotify hook for DAX faults
btrfs: disable defrag on pre-content watched files
fs: enable pre-content events on supported file systems
The diffstat is
fs/binfmt_elf.c | 4 +-
fs/binfmt_elf_fdpic.c | 4 +-
fs/btrfs/ioctl.c | 9 +++
fs/btrfs/super.c | 2 +-
fs/exec.c | 8 +-
fs/ext4/file.c | 3 +
fs/ext4/super.c | 3 +
fs/fcntl.c | 4 +-
fs/notify/fanotify/fanotify.c | 31 ++++++--
fs/notify/fanotify/fanotify.h | 15 ++++
fs/notify/fanotify/fanotify_user.c | 150 +++++++++++++++++++++++++++++--------
fs/notify/fsnotify.c | 83 +++++++++++++++++++-
fs/open.c | 62 +++++++++++----
fs/xfs/xfs_file.c | 13 ++++
fs/xfs/xfs_super.c | 2 +-
include/linux/fanotify.h | 18 +++--
include/linux/fs.h | 72 ++++++++++++++++--
include/linux/fsnotify.h | 78 ++++++++++++++-----
include/linux/fsnotify_backend.h | 53 ++++++++++++-
include/linux/mm.h | 1 +
include/uapi/asm-generic/fcntl.h | 1 -
include/uapi/linux/fanotify.h | 18 +++++
kernel/fork.c | 12 +--
mm/filemap.c | 86 +++++++++++++++++++++
mm/memory.c | 19 +++++
mm/nommu.c | 7 ++
mm/readahead.c | 14 ++++
security/selinux/hooks.c | 3 +-
28 files changed, 669 insertions(+), 106 deletions(-)
Thanks
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
