Commit 99668f61 authored by Jens Axboe's avatar Jens Axboe Committed by Al Viro

fs: expose LOOKUP_CACHED through openat2() RESOLVE_CACHED

Now that we support non-blocking path resolution internally, expose it
via openat2() in the struct open_how ->resolve flags. This allows
applications using openat2() to limit path resolution to the extent that
it is already cached.

If the lookup cannot be satisfied in a non-blocking manner, openat2(2)
will return -1/-EAGAIN.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 6c6ec2b0
......@@ -1091,6 +1091,12 @@ inline int build_open_flags(const struct open_how *how, struct open_flags *op)
lookup_flags |= LOOKUP_BENEATH;
if (how->resolve & RESOLVE_IN_ROOT)
lookup_flags |= LOOKUP_IN_ROOT;
if (how->resolve & RESOLVE_CACHED) {
/* Don't bother even trying for create/truncate/tmpfile open */
if (flags & (O_TRUNC | O_CREAT | O_TMPFILE))
return -EAGAIN;
lookup_flags |= LOOKUP_CACHED;
}
op->lookup_flags = lookup_flags;
return 0;
......
......@@ -19,7 +19,7 @@
/* List of all valid flags for the how->resolve argument: */
#define VALID_RESOLVE_FLAGS \
(RESOLVE_NO_XDEV | RESOLVE_NO_MAGICLINKS | RESOLVE_NO_SYMLINKS | \
RESOLVE_BENEATH | RESOLVE_IN_ROOT)
RESOLVE_BENEATH | RESOLVE_IN_ROOT | RESOLVE_CACHED)
/* List of all open_how "versions". */
#define OPEN_HOW_SIZE_VER0 24 /* sizeof first published struct */
......
......@@ -35,5 +35,9 @@ struct open_how {
#define RESOLVE_IN_ROOT 0x10 /* Make all jumps to "/" and ".."
be scoped inside the dirfd
(similar to chroot(2)). */
#define RESOLVE_CACHED 0x20 /* Only complete if resolution can be
completed through cached lookup. May
return -EAGAIN if that's not
possible. */
#endif /* _UAPI_LINUX_OPENAT2_H */
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