This is functionality peeled out of quick-read into a separate
Fops which modify the file (where it is required to perform the
operation on the true fd) will trigger and wait for the backend
open to succeed and use that fd.
Fops like fstat() readv() etc. will use anonymous FD (configurable)
when original fd is unopened at the backend.
Signed-off-by: Anand Avati <email@example.com>
Tested-by: Gluster Build System <firstname.lastname@example.org>
Reviewed-by: Raghavendra Bhat <email@example.com>
Reviewed-by: Jeff Darcy <firstname.lastname@example.org>