nfsd: update the fsnotify mark when setting or removing a dir delegation

Add a new helper function that will update the mask on the nfsd_file's
fsnotify_mark to be a union of all current directory delegations on an
inode.

Call that when directory delegations are added or removed, since that
can change what fsnotify events nfsd requires from the VFS layer.

The fsnotify_mark is shared by every nfsd_file open on the inode, so
concurrent delegation adds and removes on the same directory can run
nfsd_fsnotify_recalc_mask() in parallel. Because it reads the lease
state and updates the mark in two separate locked sections, a recalc
working from a stale snapshot of the lease list could clobber a
concurrent update and leave the mark missing required events. Add an
nfm_recalc_mutex to the nfsd_file_mark and hold it across the recalc to
serialize callers.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260616-dir-deleg-v7-5-6cbc7eac0ade@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>

0 files changed, 0 insertions, 0 deletions