On Tue, May 22, 2018 at 10:37:14AM -0700, Omar Sandoval wrote:
> On Tue, May 22, 2018 at 07:17:48PM +0200, David Sterba wrote:
> > On Tue, May 22, 2018 at 09:47:58AM -0700, Omar Sandoval wrote:
> > > From: Omar Sandoval <osandov@xxxxxx>
> > >
> > > Jun Wu at Facebook reported that an internal service was seeing a return
> > > value of 1 from ftruncate() on Btrfs in some cases.
> >
> > Do you have a reproducer? To estimate how likely is to hit the problem
> > in practice.
Here's an even easier one: truncating a compressed, inline file twice:
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main() {
char buf[256] = { 0 };
int ret;
int fd;
fd = open("test", O_CREAT | O_WRONLY | O_TRUNC, 0666);
if (fd == -1) {
perror("open");
return EXIT_FAILURE;
}
if (write(fd, buf, sizeof(buf)) != sizeof(buf)) {
perror("write");
close(fd);
return EXIT_FAILURE;
}
close(fd);
fd = open("test", O_WRONLY, 0666);
if (fd == -1) {
perror("open");
return EXIT_FAILURE;
}
ret = ftruncate(fd, 128);
if (ret) {
printf("first ftruncate() returned %d\n", ret);
close(fd);
return EXIT_FAILURE;
}
close(fd);
fd = open("test", O_WRONLY, 0666);
if (fd == -1) {
perror("open");
return EXIT_FAILURE;
}
ret = ftruncate(fd, 64);
if (ret) {
printf("second ftruncate() returned %d\n", ret);
close(fd);
return EXIT_FAILURE;
}
close(fd);
return EXIT_SUCCESS;
}
The output is
second ftruncate() returned 1
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