@@ -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 */
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: Jens Axboe <axboe@kernel.dk> --- fs/open.c | 6 ++++++ include/linux/fcntl.h | 2 +- include/uapi/linux/openat2.h | 4 ++++ 3 files changed, 11 insertions(+), 1 deletion(-)