Messages in this thread | | | Date | Tue, 16 Jun 2009 16:42:17 +0200 | From | Jan Kara <> | Subject | Re: [PATCH 0/10] Fix page_mkwrite() for blocksize < pagesize (version 3) |
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On Tue 16-06-09 10:34:24, Christoph Hellwig wrote: > On Mon, Jun 15, 2009 at 07:59:47PM +0200, Jan Kara wrote: > > > > patches below are an attempt to solve problems filesystems have with > > page_mkwrite() when blocksize < pagesize (see the changelog of the second patch > > for details). > > It would be useful if you had a test case reproducing these issues, > so that I can verify how well your patches work in various scenarios. Good point, I should have mentioned in the changelog: fsx-linux is able to trigger the problem quite quickly. I have also written a simple program for initial testing of the fix (works only for 1K blocksize and 4K pagesize) - it's attached.
Honza -- Jan Kara <jack@suse.cz> SUSE Labs, CR #define _XOPEN_SOURCE 500 #define _GNU_SOURCE #include <unistd.h> #include <stdio.h> #include <string.h> #include <stdlib.h> #include <fcntl.h> #include <sys/mman.h>
#define MMAP_THREADS 4
void map_file(int fd) { char *addr = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); int i;
if (addr == MAP_FAILED) { perror("mmap"); exit(1); } while (1) { for (i = 0; i < 128; i++) addr[i + 1024] = 'c'; } }
char buf2[4096] __attribute__ ((aligned (4096)));
int main(int argc, char **argv) { int i; int ret; int fd; char buf[1024];
if (argc != 2) { printf("Usage: test-mkwrite <file>\n"); return 1; } fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0644); if (fd < 0) { perror("open"); return 1; } memset(buf, 'a', sizeof(buf)); pwrite(fd, buf, sizeof(buf), 0);
for (i = 0; i < MMAP_THREADS; i++) { ret = fork(); if (ret < 0) { perror("fork"); return 1; } else if (ret == 0) map_file(fd); } close(fd);
memset(buf2, 'b', sizeof(buf2)); fd = open(argv[1], O_RDWR | O_DIRECT); if (fd < 0) { perror("dopen"); return 1; } while (1) { if (pwrite(fd, buf2, 4096, 4096) < 0) perror("pwrite"); usleep(10000000); ftruncate(fd, 1024); usleep(10000000); } return 0; }
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