condition was addressed in libpuffs by counting lookups.
The fix assumes that cookies map to struct puffs_cookie, which has not
been documented as a requirement for filesystems using libpuffs. As an
example, we got burnt by this assumption in libp2k (kern/46734), and
we fixed bit by actually mapping libp2k cookies to struct puffs_node.
It is unlikely, but there may be third party filesystems that use cookies
unmapped to struct puffs_node, and they were left broken for now.
- we introduce a puffs_init() flag PUFFS_FLAG_PNCOOKIE that let filesystems
inform libpuffs that they map cookies to struct puffs_node. Is that flag
is used, the lookup/reclaim race condition fix is enabled. We enable the
flag for libp2k.
- filesystems that use puffs_pn_new() obviouslty use struct puffs_node
and gain PUFFS_FLAG_PNCOOKIE automatically even if they did not specify
it in puffs_init(). This include all our PUFFS filesystem in-tree except
libp2k.
- for filesystems not willing to use struct puffs_node, we introduce a
reclaim2 vnop, which is reclaim with an additionnal lookup count argument.
This vnop let the filesystem implement the lookup/reclaim race fix on
its own.
leads to struct p2k_node corruption now that libpuffs used pn_nlookup field
in struct puffs_node to avoid race conditions.
Attempt to fix that by adding a struct puffs_node at the beginning of struct
p2k_node. This seems to fix kern/46734
filesystem in which format extended attribute shall be listed.
There are currently two formats:
- NUL-terminated strings, used for listxattr(2), this is the default.
- one byte length-pprefixed, non NUL-terminated strings, used for
extattr_list_file(2), which is obtanined by setting the
EXTATTR_LIST_PREFIXLEN flag to VOP_LISTEXTATTR(9)
This approach avoid the need for converting the list back and forth, except
in libperfuse, since FUSE uses NUL-terminated strings, and the kernel may
have requested EXTATTR_LIST_PREFIXLEN.
process receives SIGINFO. Additionally, dump vnode status if the
process gets SIGUSR1 (can be quite quite verbose, therefore not
displayed with SIGINFO).
However, because of a protocol deficiency puffs relies on being able
to keep track of VOP_LOOKUP calls by inspecting their contents, and
this at least allows it to use something vaguely principled instead of
making wild guesses based on whether SAVESTART is set.
Update libp2k to use INRELOOKUP instead of SAVESTART.
(after some changes to rump) actually free those pages, leaving
the tmpfs vnode feeling quite empty.
(the purpose of the flush is to avoid double caching between the
rump kernel and puffs vfs layer)
