Hi Jens, On 2/21/21 2:12 PM, Jens Axboe wrote: > RESOLVE_CACHED allows an application to attempt a cache-only open > of a file. If this isn't possible, the request will fail with > -1/EAGAIN and the caller should retry without RESOLVE_CACHED set. > This will generally happen from a different context, where a slower > open operation can be performed. > > Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Is it correct that this feature is now merged? Cheers, Michael > > --- > > Since v2: > - Incorporate suggested edits from Michael > > diff --git a/man2/openat2.2 b/man2/openat2.2 > index 3bda20620574..a8381c753f0d 100644 > --- a/man2/openat2.2 > +++ b/man2/openat2.2 > @@ -385,6 +385,17 @@ This may occur if, for example, > a system pathname that is used by an application is modified > (e.g., in a new distribution release) > so that a pathname component (now) contains a bind mount. > +.TP > +.B RESOLVE_CACHED > +Make the open operation fail unless all path components are already present > +in the kernel's lookup cache. > +If any kind of revalidation or I/O is needed to satisfy the lookup, > +.BR openat2 () > +fails with the error > +.B EAGAIN . > +This is useful in providing a fast-path open that can be performed without > +resorting to thread offload, or other mechanisms that an application might > +use to offload slower operations. > .RE > .IP > If any bits other than those listed above are set in > @@ -421,6 +432,14 @@ The caller may choose to retry the > .BR openat2 () > call. > .TP > +.B EAGAIN > +.BR RESOLVE_CACHED > +was set, and the open operation cannot be performed using only cached > +information. The caller should retry without > +.B RESOLVE_CACHED > +set in > +.I how.resolve . > +.TP > .B EINVAL > An unknown flag or invalid value was specified in > .IR how . > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
