On Fri 15-11-24 12:28:01, Amir Goldstein wrote:
> On Tue, Nov 12, 2024 at 6:56 PM Josef Bacik <josef@xxxxxxxxxxxxxx> wrote:
> >
> > From: Amir Goldstein <amir73il@xxxxxxxxx>
> >
> > Similar to FAN_ACCESS_PERM permission event, but it is only allowed with
> > class FAN_CLASS_PRE_CONTENT and only allowed on regular files and dirs.
> >
> > Unlike FAN_ACCESS_PERM, it is safe to write to the file being accessed
> > in the context of the event handler.
> >
> > This pre-content event is meant to be used by hierarchical storage
> > managers that want to fill the content of files on first read access.
> >
> > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> > ---
> > fs/notify/fanotify/fanotify.c | 3 ++-
> > fs/notify/fanotify/fanotify_user.c | 22 +++++++++++++++++++---
> > include/linux/fanotify.h | 14 ++++++++++----
> > include/uapi/linux/fanotify.h | 2 ++
> > 4 files changed, 33 insertions(+), 8 deletions(-)
> >
> > diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> > index 2e6ba94ec405..da6c3c1c7edf 100644
> > --- a/fs/notify/fanotify/fanotify.c
> > +++ b/fs/notify/fanotify/fanotify.c
> > @@ -916,8 +916,9 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
> > BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
> > BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR);
> > BUILD_BUG_ON(FAN_RENAME != FS_RENAME);
> > + BUILD_BUG_ON(FAN_PRE_ACCESS != FS_PRE_ACCESS);
> >
> > - BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 21);
> > + BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 22);
> >
> > mask = fanotify_group_event_mask(group, iter_info, &match_mask,
> > mask, data, data_type, dir);
> > diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> > index 9cc4a9ac1515..2ec0cc9c85cf 100644
> > --- a/fs/notify/fanotify/fanotify_user.c
> > +++ b/fs/notify/fanotify/fanotify_user.c
> > @@ -1633,11 +1633,23 @@ static int fanotify_events_supported(struct fsnotify_group *group,
> > unsigned int flags)
> > {
> > unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
> > + bool is_dir = d_is_dir(path->dentry);
> > /* Strict validation of events in non-dir inode mask with v5.17+ APIs */
> > bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) ||
> > (mask & FAN_RENAME) ||
> > (flags & FAN_MARK_IGNORE);
> >
> > + /*
> > + * Filesystems need to opt-into pre-content evnets (a.k.a HSM)
> > + * and they are only supported on regular files and directories.
> > + */
> > + if (mask & FANOTIFY_PRE_CONTENT_EVENTS) {
> > + if (!(path->mnt->mnt_sb->s_iflags & SB_I_ALLOW_HSM))
> > + return -EINVAL;
>
> Should we make this return -EOPNOTSUPP?
I see no reason not to do that so go ahead.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
