On 06/19/2012 01:22 PM, Andrew Morton wrote:
> On Tue, 19 Jun 2012 10:57:27 +0530 Suresh Jayaraman <sjayaraman@xxxxxxxx> wrote:
>
>>> How extensively was this change tested? Please describe the testing
>>> which was performed?
>>>
>>
>> The original patch was tested by mounting a NFS share with fscache
>> option enabled, do a md5sum on a nfs file larger than 2GB and ensure
>> that the file is getting cached by fscache (watch cache size growing)
>> on x86_64.
>
> Well it will need a lot more coverage testing than that. truncate?
> expanding truncate? write, lseek, pwrite, pread(), mmap(MAP_SHARED),
> behavior at the new max file size (what is that?), etc.
>
The changelog could be slightly misleading as the patch doesn't really
add LFS support. It just passes O_LARGEFILE flag to dentry_open() to make
VFS allow cachefiles to open larger files (instead of failing it with
-EOVERFLOW). Cachefiles is just a cache that uses the VFS/VM interfaces to
get another disk filesystem to do the requisite I/O on its behalf.
So, I doubt whether more coverage testing is required for this change.
Anyway, I'm attaching a quick and dirty test program that might help
(not well tested though). I'm unable to to test it as I have modified
my setup and have to redo it.
Justin, do you have the setup and can you get this tested?
/*
* Few tests to ensure LFS (Large File Support) is working correctly.
*
* The requests (seek, truncate, write, mmap etc) that extend beyond the offset
* maximum (off_t) should succeed.
*
* Compile it with -D_FILE_OFFSET_BITS=64
*
* Run it like:
* ./lfs-tests large_file
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#define BUF_SZ 32
#define err(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
void report_size(int fd, struct stat *st)
{
fstat(fd, st);
printf("size of file: %ld\n", st->st_size);
return;
}
int main(int argc, char *argv[])
{
int fd;
int rc = 0;
unsigned long offset = 0;
struct stat stbuf;
char buf[BUF_SZ];
void *file_mem;
if (argc != 2) {
fprintf(stderr, "Usage: %s test_file\n", argv[0]);
exit(EXIT_FAILURE);
}
fd = open(argv[1], O_RDWR | O_APPEND);
if (fd == -1)
err("open");
memset(buf, 0, sizeof(buf));
/* seek to the end of file */
offset = lseek(fd, 0, SEEK_END);
if (offset < 0)
err("lseek");
/* seek past the end of file */
offset = lseek(fd, BUF_SZ, SEEK_END);
printf("%ld\n", offset);
if (offset < 0)
err("lseek");
/* truncate it to < 2GB and report size */
rc = ftruncate(fd, 2147483648 - BUF_SZ);
if (rc != 0)
err("ftruncate");
report_size(fd, &stbuf);
/* truncate it to a size larger than 2GB */
rc = ftruncate(fd, 4294967360);
if (rc != 0)
err("ftruncate");
report_size(fd, &stbuf);
/* seek to the end of file */
offset = lseek(fd, 0, SEEK_END);
if (offset < 0)
err("lseek");
memset(buf, 'a', sizeof(buf));
/* write past 4GB */
rc = write(fd, buf, sizeof(buf));
if (rc == -1)
err("write");
report_size(fd, &stbuf);
offset = lseek(fd, 0, SEEK_END);
if (offset < 0)
err("lseek");
/* pwrite and pread */
rc = pread(fd, buf, BUF_SZ, offset);
if (rc == -1)
err("pread");
rc = pwrite(fd, buf, sizeof(buf), offset);
if (rc == -1)
err("pwrite");
report_size(fd, &stbuf);
/* page align offset */
offset = offset & ~(sysconf(_SC_PAGE_SIZE) - 1);
file_mem = mmap(0, BUF_SZ, PROT_WRITE, MAP_SHARED, fd, offset);
if (file_mem == MAP_FAILED)
err("mmap");
munmap(file_mem, 64);
close(fd);
return EXIT_SUCCESS;
}
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