possible endianes bug in mkfs.f2fs roll-forward speed

possible endianes bug in mkfs.f2fs roll-forward speed

[joerg jungermann]

Hi,

I might found a bug in mkfs.f2fs. while experimenting with f2fs on my big
endian MIPS32 device (platform lantiq, 14.07-rc3, uclibc).

I ran into an issue that mkfs.f2fs, was not able to format block devices if i did not
specify the sector count manually.

I hunted it down to lib/libf2fs.c.
After I found that the detected sector count equals to the wanted sector count shifted left (32+9) times.

I found two issues:
Firstly it uses ioctl BLKGETSIZE, which writes to an uint32_t the size of the device.
As c->total_sectors is of type uint64_t, the value is written in to the first 4 bytes.
That explained the left shift of 32 bits.

Secondly BLKGETSIZE determines the size of the device in bytes (AFAIK, learned by observation).
In the first branch of the if-block patched below, the c->total_sectors is calculated by
  c->total_sectors = stat_buf.st_size / c->sector_size;
The else branch omits the devision. sector_sice is mostly 512, that explained the left shift by 9 bytes.

I prepared patch against 1.4.0, not HEAD, sorry.
 * fixes sector count calculation
 * uses BLKGETSIZE64 if avail

best regards


--- lib/libf2fs.c.orig  2014-09-25 17:41:56.433763287 +0200
+++ lib/libf2fs.c       2014-09-25 17:45:04.944604490 +0200
@@ -453,11 +453,21 @@
                                c->sectors_per_blk = PAGE_SIZE / sector_size;
                        }
                }
-
-               if (ioctl(fd, BLKGETSIZE, &c->total_sectors) < 0) {
+#ifdef BLKGETSIZE64
+               if (ioctl(fd, BLKGETSIZE64, &c->total_sectors) < 0) {
+                       MSG(0, "\tError: Cannot get the device size\n");
+                       return -1;
+               }
+    c->total_sectors /= c->sector_size;
+#else
+         uint32_t total_sectors;
+               if (ioctl(fd, BLKGETSIZE, &total_sectors) < 0) {
                        MSG(0, "\tError: Cannot get the device size\n");
                        return -1;
                }
+    total_sectors /= c->sector_size;
+    c->total_sectors = total_sectors;
+#endif
 
                if (ioctl(fd, HDIO_GETGEO, &geom) < 0)
                        c->start_sector = 0;


-- 
Joerg Jungermann

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