Hi Jens, On 12/17/20 10:18 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> I take it that this feature is not yet merged into the kernel? (At least, I couldn't grep RESOLVE_CACHED in current kernel sources.) > > --- > > First attempt at this, fully expecting the phrasing to require some > massaging. > > Also see: https://lore.kernel.org/linux-fsdevel/20201217161911.743222-1-axboe@xxxxxxxxx/T/ > > diff --git a/man2/openat2.2 b/man2/openat2.2 > index 3bda20620574..282c13e2df96 100644 > --- a/man2/openat2.2 > +++ b/man2/openat2.2 > @@ -385,6 +385,15 @@ 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 > +Fail path resolution, unless all components needed already exist in the I think "Fail path resolution" needs some clarification. Maybe something like: [[ Make the open operation fail unless all path components are already present in the kernel's lookup cache. ]] ? > +lookup cache. If any kind of revalidation or IO is needed to satisfy the ^ Please start new sentences on new lines. Using such-called "semantic newlines" makes for cleaner future patches. > +lookup, then fail the open attempt with "fail the open attempt with" ==> .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 mechanism that an application might > +use to offload slower operations. > .RE > .IP > If any bits other than those listed above are set in > @@ -421,6 +430,14 @@ 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 cached. The caller should semantic newline > +retry without > +.B RESOLVE_CACHED > +set in > +.I how.resolve > +.TP > .B EINVAL > An unknown flag or invalid value was specified in > .IR how . Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
