https://bugzilla.kernel.org/show_bug.cgi?id=50981 Summary: ext4 : DATA CORRUPTION read and write on same 4096 page range Product: File System Version: 2.5 Kernel Version: 2.6.32 Red Hat Enterprise Linux Workstation release 6.2 (Santiago) Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: high Priority: P1 Component: ext4 AssignedTo: fs_ext4@xxxxxxxxxxxxxxxxxxxx ReportedBy: meetmehiro@xxxxxxxxx Regression: No Kernal version and Red hat 2.6.32 , Red Hat Enterprise Linux Workstation release 6.2 (Santiago) I have one scientific application, that is running on ext4 , after three to fours days, I have started to seen that data is not correct.. then i tried to find simple reproducer for the same. Pl. find the reproducer for the same with this issue is hitting easily. Logs : ./sim ext4_write creating the threads writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... reader thread has opened the file, fd : 4 reader..checking data integrity writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... reader..checking data integrity writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... reader..checking data integrity writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... reader..checking data integrity writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... reader..checking data integrity writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... reader..checking data integrity writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... reader..checking data integrity writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... reader..checking data integrity writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... reader..checking data integrity writing A at offset 0... writing B at offset 0... writing A at offset 0... reader..checking data integrity writing B at offset 0... writing A at offset 0... reader..checking data integrity writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... reader..checking data integrity writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... reader..checking data integrity writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... reader..checking data integrity writing A at offset 0... writing B at offset 0... writing A at offset 0... writing B at offset 0... reader..checking data integrity writing A at offset 0... reader.. corrupted data, at offset : 511 writing B at offset 0... C program : #include <stdio.h> #include <fcntl.h> #include <pthread.h> #include <assert.h> #include <errno.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <sys/mman.h> pthread_t reader_id, writer_id; char write_buf [4096] = {0,}; char read_buf[4096] = {0,}; char datafile[256] = {0,}; int stop_write = 0; void * writer (void * arg) { int fd = -1; int count = 0; /* this thread will open the file and write 4k data to it alternatively * of a different data set to the same offset */ /* opening the file */ assert((fd = open(datafile, O_CREAT|O_RDWR, 0777)) != -1); while (1) { if (stop_write) { close(fd); printf("write stopped\n"); return NULL; } if (count % 2 == 0) memset(write_buf, 'A', sizeof(write_buf)); else memset(write_buf, 'B', sizeof(write_buf)); assert(lseek(fd, 0, SEEK_SET) == 0); printf("writing %c at offset 0...\n", write_buf[0]); assert(write(fd, write_buf, 4096) == 4096); count ++; } //pthread_exit((void *)0); close(fd); return NULL; } void * reader(void * arg) { int fd = -1; int count = 0; /* this thread will open the file and write 4k data to it alternatively * of a different data set to the same offset */ /* opening the file */ assert((fd = open(datafile, O_CREAT|O_RDWR, 0777)) != -1); printf("reader thread has opened the file, fd : %d\n", fd); while (1) { memset(read_buf, '\0', 4096); assert(lseek(fd, 0, SEEK_SET) == 0); assert(read(fd, read_buf, 4096) == 4096); count ++; printf("reader..checking data integrity\n"); int i=0; for (i=0; i < 4095; i++) { int prev_char = read_buf[i]; int next_char = read_buf[i+1]; if (prev_char != next_char) { printf("reader.. corrupted data, at offset : %d\n", i); stop_write = 1; int output_fd = open("res.txt", O_CREAT|O_RDWR, 0777); assert(write(output_fd, read_buf, 4096) == 4096); close(output_fd); close(fd); return NULL; } } } //pthread_exit((void *)0); close(fd); return NULL; } int main (int argc, char *argv[]) { pthread_attr_t attr; void * arg = NULL; int *status; int err = 0; if (argc != 2) { printf("usage : ./reader_writer <file pathname>\n"); exit(1); } memset(datafile, '\0', sizeof(datafile)); strcpy(datafile, argv[1]); pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE); /* create the reader and writer thread */ printf("creating the threads\n"); if ((err = pthread_create(&writer_id, &attr, writer, (void *)arg)) != 0) { printf ("pthread_create failed err no :%d\n", err); } if ((err = pthread_create(&reader_id, &attr, reader, (void *)arg)) != 0) { printf ("pthread_create failed err no :%d\n", err); } pthread_attr_destroy(&attr); /* Wait on the other threads */ assert(pthread_join(writer_id, (void *)&status) == 0); assert(pthread_join(reader_id, (void *)&status) == 0); pthread_exit(NULL); } How to run gcc program.c -o ext4_program -lpthread ./ext4_program ext4_write -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
