On Sat, Mar 10, 2012 at 12:02:40PM -0600, Richard Laager wrote: > If we could probe for FALLOC_FL_PUNCH_HOLE support, then we could avoid > advertising discard support based on FALLOC_FL_PUNCH_HOLE when it is not > going to work. This would side step these problems. You said it wasn't > possible to probe for FALLOC_FL_PUNCH_HOLE. Have you considered probing > by extending the file by one byte and then punching that: > char buf = 0; > fstat(s->fd, &st); > pwrite(s->fd, &buf, 1, st.st_size + 1); > has_discard = !fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | > FALLOC_FL_KEEP_SIZE,
There is no point in using FALLOC_FL_KEEP_SIZE together with FALLOC_FL_PUNCH_HOLE.
