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

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

fs/open.c

+6 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/fcntl.h

+1 −1
Original line number Diff line number Diff line
@@ -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 */

include/uapi/linux/openat2.h

+4 −0
Original line number Diff line number Diff line
@@ -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 */