Date: Wed, 31 Jan 2018 13:40:48 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 225586] ftruncate+mmap+fsync fails for small maps Message-ID: <bug-225586-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D225586 Bug ID: 225586 Summary: ftruncate+mmap+fsync fails for small maps Product: Base System Version: 11.1-STABLE Hardware: amd64 OS: Any Status: New Severity: Affects Many People Priority: --- Component: misc Assignee: freebsd-bugs@FreeBSD.org Reporter: tris_vern@hotmail.com Created attachment 190220 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D190220&action= =3Dedit test on tmp filesystem that can be unmounted When doing an ftruncate+mmap+fsync to a size less than 512 bytes the data n= ever seems to be sync'd properly to disk. This work fine on the latest 11.1-RELEASE but not the latest 11.1-STABLE. I= t is also ok if the ftruncate is to the existing file size. While the mapped changes are visible in the file before an umount, after ev= en a failed umount, the changes are no longer present. (non-error checked) C code below. After running the binary, check the contents of the file (eg hd) and it wil= l be all 0xFF. Then, umount the filesystem you are on*. Then check the contents = of the file again. It will now be 0x01. Running extra sync's or fsync's from the command line before the umount doe= sn't seem to help. * The umount should fail but still shows the problem. However note it doesn= 't seem to work with the error given for the root filesystem "/". I've also attached a script that creates a filesystem to umount --- #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <string.h> #include <sys/mman.h> int main (int argc, char *argv[]) { int fd; size_t i, size1, size2; char *data; char *filename; char pattern =3D 0x01; if (argc < 2) { fprintf(stderr, "Usage: %s filename size1 size2\n", argv[0]); exit(1); } filename =3D argv[1]; size1 =3D atoi(argv[2]); size2 =3D atoi(argv[3]); fd =3D open(filename, O_RDWR | O_TRUNC | O_CREAT, 0644); for (i =3D 0; i < size1; i++) write(fd, &pattern, 1); close(fd); fd =3D open(filename, O_RDWR, 0644); ftruncate(fd, size2); data =3D mmap(NULL, size2, PROT_READ|PROT_WRITE,MAP_SHARED,fd,0); memset(data, 0xFF, size2); fsync(fd); munmap(data, size2); close(fd); } --=20 You are receiving this mail because: You are the assignee for the bug.=
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