Fix segfault when passing in size < block_size

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

diff --git a/io_u.c b/io_u.c
index 6d539a01fbdaec105144c2b93252683a4630af46..8cc348a835fed67a2310c04f84b4608281db1315 100644 (file)
--- a/io_u.c
+++ b/io_u.c
@@ -126,16 +126,20 @@ static unsigned long long last_block(struct thread_data *td, struct fio_file *f,
 static int get_next_free_block(struct thread_data *td, struct fio_file *f,
                               enum fio_ddir ddir, unsigned long long *b)
 {
-       unsigned long long min_bs = td->o.rw_min_bs;
+       unsigned long long min_bs = td->o.rw_min_bs, lastb;
        int i;
 
+       lastb = last_block(td, f, ddir);
+       if (!lastb)
+               return 1;
+
        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))
+                       if (*b > lastb)
                                break;
                        f->last_free_lookup = i;
                        return 0;
@@ -152,14 +156,17 @@ static int get_next_free_block(struct thread_data *td, struct fio_file *f,
 static int get_next_rand_offset(struct thread_data *td, struct fio_file *f,
                                enum fio_ddir ddir, unsigned long long *b)
 {
-       unsigned long long r;
+       unsigned long long r, lastb;
        int loops = 5;
 
+       lastb = last_block(td, f, ddir);
+       if (!lastb)
+               return 1;
+
        do {
                r = os_random_long(&td->random_state);
                dprint(FD_RANDOM, "off rand %llu\n", r);
-               *b = (last_block(td, f, ddir) - 1)
-                       * (r / ((unsigned long long) OS_RAND_MAX + 1.0));
+               *b = (lastb - 1) * (r / ((unsigned long long) OS_RAND_MAX + 1.0));
 
                /*
                 * if we are not maintaining a random map, we are done.