Issue running random reads with verify on a raw device

[Radha Ramachandran <radha@xxxxxxxxxx>]

Hi,
We have a test that runs the test on a raw device say of size 100GB
> Sequential write of a pattern to the raw device with size=10GB (so even though the device is 100GB big we try to write only to the first 10GB)
> Random read and verify of the pattern to the raw device with size=10GB, (with randommap, so we maintain the bitmap of previously visited blocks)

This test almost always lands up trying to do the read beyond the
10GB. So I see this code in io_u.c:

static int get_next_free_block(struct thread_data *td, struct fio_file *f,
			       enum fio_ddir ddir, unsigned long long *b) {
...
       while ((*b) * min_bs < f->real_file_size) {   ========= This
code looks for an unvisited block within the real_file_size which in
this case is 100GB, and will exceed 10GB in a lot of cases causing the
verify to fail.


So i fixed this by checking if the block is within the real_file_size
and the io_size, so this wld work in cases where:
1. Actual file size < io_size
2. io_size < Actual file size


diff -crB io_u.c io_u.c_fixed
*** io_u.c      Fri Apr 10 15:47:02 2009
--- io_u.c_fixed        Fri Apr 10 15:48:02 2009
***************
*** 113,119 ****

        i = f->last_free_lookup;
        *b = (i * BLOCKS_PER_MAP);
!       while ((*b) * min_bs < f->real_file_size) {
                if (f->file_map[i] != (unsigned int) -1) {
                        *b += ffz(f->file_map[i]);
                        if (*b > last_block(td, f, ddir))
--- 113,120 ----

        i = f->last_free_lookup;
        *b = (i * BLOCKS_PER_MAP);
!       while (((*b) * min_bs < f->real_file_size) &&
!               ((*b) * min_bs < f->io_size)) {
                if (f->file_map[i] != (unsigned int) -1) {
                        *b += ffz(f->file_map[i]);
                        if (*b > last_block(td, f, ddir))


Is there some case I missed?
thanks
-radha
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