shmem: allow reporting fanotify events with file handles on tmpfs

Since kernel v5.1, fanotify_init(2) supports the flag FAN_REPORT_FID
for identifying objects using file handle and fsid in events.

fanotify_mark(2) fails with -ENODEV when trying to set a mark on
filesystems that report null f_fsid in stasfs(2).

Use the digest of uuid as f_fsid for tmpfs to uniquely identify tmpfs
objects as best as possible and allow setting an fanotify mark that
reports events with file handles on tmpfs.

Link: https://lore.kernel.org/r/[email protected]
Acked-by: Hugh Dickins <[email protected]>
Reviewed-by: Christian Brauner <[email protected]>
Signed-off-by: Amir Goldstein <[email protected]>
Signed-off-by: Jan Kara <[email protected]>

0 files changed, 0 insertions, 0 deletions