Bug#664088: mdadm fails to initialize components for bitmap

[Michael Tokarev]

tags 664088 confirmed fixed-upstream
thanks

> Package: mdadm
> Version: 3.2.3-2
> Severity: normal
> 
> Hi,
> 
> When trying to add a bitmap to a freshly created device, I get an error:

> # mdadm -G -b internal /dev/md0
> mdadm: failed to set internal bitmap.

> A strace of the mdadm -G command contained the following snippet:
> 
> open("/dev/vdb", O_RDWR|O_DIRECT)       = 4
> fstat(4, {st_mode=S_IFBLK|S_ISVTX|0660, st_rdev=makedev(254, 16), ...}) = 0
> ioctl(4, BLKGETSIZE64, 0x7fffc64838d0)  = 0
> ioctl(4, BLKFLSBUF, 0)                  = 0
> lseek(4, 4096, SEEK_SET)                = 4096
> ioctl(4, BLKSSZGET, 0x7fffc64838cc)     = 0
> read(4, "\374N+\251\1\0\0\0\0\0\0\0\0\0\0\0\371\323O\276]W~\353-2\27034U\246\216"..., 1024) = 1024
> lseek(4, 8192, SEEK_SET)                = 8192
> ioctl(4, BLKSSZGET, 0x7fffc648296c)     = 0
> write(4, "bitm\4\0\0\0\371\323O\276]W~\353-2\27034U\246\216\0\0\0\0\0\0\0\0"..., 512) = -1 EINVAL (Invalid argument)
> fsync(4)                                = 0
> close(4)                                = 0
> 
> (Followed by a similar one for vdc.)
> 
> There are at least two bugs here:
> 
> 1) mdadm opens the device with O_DIRECT but fails to do page aligned
>    writes (a requirement for O_DIRECT).
> 
> 2) mdadm does not check the return code of its write() calls.

This has been fixed upstream for the next version.

See:
 https://bugzilla.redhat.com/show_bug.cgi?id=789898
 http://neil.brown.name/git?p=mdadm;h=d669228f295e4c695475f0c1f7dc52f514a177c4

Apparently it only fixes the 1) case, not 2).

In any way, the fix will be in the next release.

Thanks,

/mjt