Fixup for a minor 0 byte file size case

When a file size calculated by (size / nrfiles) happens to be 0 in
setup_files(), it simply sets ->file_size to ->real_file_size which
means the size is set to the existing file size (if any) or 0.

Add log_info() to show that it's been set that way, and also 0 byte
file isn't likely to be created in the first place. Also add a check
to avoid negative file size.

This usually doesn't happen unless one tries to make it happen by
for e.g. using a small size= and large nrfiles= options.

Signed-off-by: Tomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/HOWTO b/HOWTO
index 7884944a763d55436b365e8ca90c83cfbb9f5505..6d903bba0cb372745767ca7f81afcd19aefbc544 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -1513,7 +1513,7 @@ I/O size
        Fio will divide this size between the available files determined by options
        such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
        specified by the job. If the result of division happens to be 0, the size is
-       set to the physical size of the given files or devices.
+       set to the physical size of the given files or devices if they exist.
        If this option is not specified, fio will use the full size of the given
        files or devices.  If the files do not exist, size must be given. It is also
        possible to give size as a percentage between 1 and 100. If ``size=20%`` is

diff --git a/filesetup.c b/filesetup.c
index ae7f8171305507d9a28417cb5afb74181cc4c655..9388bfc94b419e54e670b7410affda94c97ef9ea 100644 (file)
--- a/filesetup.c
+++ b/filesetup.c
@@ -904,8 +904,7 @@ int setup_files(struct thread_data *td)
                if (!o->file_size_low) {
                        /*
                         * no file size or range given, file size is equal to
-                        * total size divided by number of files. If that is
-                        * zero, set it to the real file size. If the size
+                        * total size divided by number of files. If the size
                         * doesn't divide nicely with the min blocksize,
                         * make the first files bigger.
                         */
@@ -915,8 +914,24 @@ int setup_files(struct thread_data *td)
                                f->io_size += bs;
                        }
 
-                       if (!f->io_size)
+                       /*
+                        * We normally don't come here, but if the result is 0,
+                        * set it to the real file size. This could be size of
+                        * the existing one if it already exists, but otherwise
+                        * will be set to 0. A new file won't be created because
+                        * ->io_size + ->file_offset equals ->real_file_size.
+                        */
+                       if (!f->io_size) {
+                               if (f->file_offset > f->real_file_size)
+                                       goto err_offset;
                                f->io_size = f->real_file_size - f->file_offset;
+                               log_info("fio: forcing file %s size to %llu\n",
+                                       f->file_name,
+                                       (unsigned long long)f->io_size);
+                               if (!f->io_size)
+                                       log_info("fio: file %s may be ignored\n",
+                                               f->file_name);
+                       }
                } else if (f->real_file_size < o->file_size_low ||
                           f->real_file_size > o->file_size_high) {
                        if (f->file_offset > o->file_size_low)