9:56 a.m.
You may not have done anything from client that does:
fd = open(“foo”, O_RDWR + O_CREAT + O_TRUNC, 0666)
Try
echo foo > /mnt/foo
from the client, and then run it again (so you get both the create case and the already
exists case.
Frank
From: Sachin Punadikar [mailto:punadikar.sachin@gmail.com]
Sent: Wednesday, October 24, 2018 4:07 AM
To: Daniel Gryniewicz <dang(a)redhat.com>
Cc: devel(a)lists.nfs-ganesha.org
Subject: [NFS-Ganesha-Devel] Re: read-only open causing file to be truncated with
NFSv4/ganesha.
Hi Daniel,
Here is the code snippet from fsal_open2 function:
/* Handle attribute size = 0 here, normalize to FSAL_O_TRUNC
* instead of setting ATTR_SIZE.
*/
if (attr != NULL &&
FSAL_TEST_MASK(attr->valid_mask, ATTR_SIZE) &&
attr->filesize == 0) {
LogFullDebug(COMPONENT_FSAL, "Truncate");
/* Handle truncate to zero on open */
openflags |= FSAL_O_TRUNC;
/* Don't set the size if we later set the attributes */
FSAL_UNSET_MASK(attr->valid_mask, ATTR_SIZE);
}
If I enable full debug, I could see "Truncate" being logged only when the file
is new. For existing files, "Truncate" log entry was never seen.
Hence I mentioned that it gets applied to only new files.
On Tue, Oct 23, 2018 at 7:27 PM Daniel Gryniewicz <dang(a)redhat.com
<mailto:dang@redhat.com> > wrote:
Where are you seeing this? It looks to me like FSAL_O_TRUNC is applied
on all opens.
Daniel
On 10/23/2018 06:42 AM, Sachin Punadikar wrote:
I have uploaded a patch to fix this
(https://review.gerrithub.io/c/ffilz/nfs-ganesha/+/430435)
But I have a question on this.
As per the code, the O_TRUNC gets applied (via open_flags) only when it
is file create. If the file pre-exists, O_TRUNC is not applied to
open_flags.
Was wondering, why we need O_TRUNC while creating new file, anyway it
will be of size 0 ?
As per my little understanding the O_TRUNC should be applicable if we
are opening a pre-existing file. Correct me if I am wrong.
On Mon, Oct 15, 2018 at 6:32 PM Daniel Gryniewicz <dang(a)redhat.com
<mailto:dang@redhat.com>
<mailto:dang@redhat.com <mailto:dang@redhat.com> >> wrote:
This seems like a bug. My guess is that either status2() shouldn't
return O_TRUNC, or it shouldn't be saved in the fd to begin with.
O_TRUNC is a transitory flag, only useful at the time of the open
itself.
Fixing the common status2() is simplest; otherwise we need to fix all
the FSALs.
Daniel
On 10/12/2018 08:12 PM, Pradeep wrote:
> Hello,
>
> I'm seeing an issue with a specific application flow and with
ganesha
> server (2.6.5). Here is what the application does:
>
> - fd1 = open (file1, O_WRONLY|O_CREAT|O_TRUNC)
> Ganesha creates a state and stores the flags in fd->openflags
(see
> vfs_open2())
> - write (fd1, ....)
> - fd2 = open(file1, O_RDONLY)
> Ganesha finds the state for the first open, finds the flags
and calls
> fsal_reopen2() with old and new flags OR'd together. This causes the
> file to be truncated because the original open was done with O_TRUNC.
>
> I don't see this behavior with kernel NFS or a local filesystem. Any
> suggestions on fixing this? Here is a quick and dirty program to
> reproduce it - you can see that the second stat prints zero as
size with
> a mount from Ganesha server.
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <sys/stat.h>
> #include <unistd.h>
>
> int main(int argc, char **argv)
> {
> char *fn = argv[1];
> int fd;
> char buf[1024];
> struct stat stbuf;
> int rc;
>
>
> fd = open(fn, O_WRONLY|O_CREAT|O_TRUNC, 0666);
> printf("open(%s) = %d\n", fn, fd);
>
> ssize_t ret;
> ret = write(fd, buf, sizeof(buf));
> printf("write returned %ld\n", ret);
>
> rc = stat(fn, &stbuf);
> printf("size: %ld\n", stbuf.st_size);
>
> int fd1;
> fd1 = open(fn, O_RDONLY);
> printf("open(%s) = %d\n", fn, fd1);
>
> rc = stat(fn, &stbuf);
> printf("size: %ld\n", stbuf.st_size);
> }
>
> Thanks,
> Pradeep
>
>
>
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--
with regards,
Sachin Punadikar
--
with regards,
Sachin Punadikar