On Wed, Sep 2, 2015 at 10:00 AM, Janusz Borkowski
<janusz.borkowski@xxxxxxxxxxxxxx> wrote:
> Hi!
>
> I mount cephfs using kernel client (3.10.0-229.11.1.el7.x86_64).
>
> The effect is the same when doing "echo >>" from another machine and from a
> machine keeping the file open.
>
> The file is opened with open( ..,
> O_WRONLY|O_LARGEFILE|O_APPEND|O_BINARY|O_CREAT)
>
> Shell ">>" is implemented as (from strace bash -c "echo '7789' >>
> /mnt/ceph/test):
>
> open("/mnt/ceph/test", O_WRONLY|O_CREAT|O_APPEND, 0666) = 3
>
> The test file had ~500KB size.
>
> Each subsequent "echo >>" writes to the start of the test file, first "echo"
> overwriting the original contents, next "echos" overwriting bytes written by
> the preceding "echo".
Hmmm. The userspace (ie, ceph-fuse) implementation of this is a little
bit racy but ought to work. I'm not as familiar with the kernel code
but I'm not seeing any special behavior in the Ceph code — Zheng,
would you expect this to work? It looks like some of the linux
filesystems have their own O_APPEND handling and some don't, but I
can't find it in the VFS either.
-Greg
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
