I will try to elaborate more about the problem and steps to reproduce: Linux version 3.4.0 on X86 box. Step1: First create a small partition as it would be easy to fragment quickly. The main intent for fragmenting the partition is to create a file with at least 2 extent indexes. You can also choose some other method to create such a file. I created 200Mb partition and while formating used blocksize as 4KB and used attached script to fragment. This script fragments the partition such that each extent is exactly 6FS blocks OR 24KB in length. Linux#> ./fragment.sh /mnt/ 6+0 records in 6+0 records out 24576 bytes (24.0KB) copied, 0.087997 seconds, 272.7KB/s cp: write error: No space left on device Partition filled rm: can't remove '/mnt//file1.7564': No such file or directory fragmented partition /mnt/ with 24KB files Step2: Create a file with 342 extents i.e 2 extent indexes [root@sputnik ashish]# dd if=linux-3.4.tar.bz2 of=check_1 bs=24576 count=342 342+0 records in 342+0 records out 8404992 bytes (8.4 MB) copied, 0.0913289 s, 92.0 MB/s [root@sputnik ashish]# cp check_1 /mnt/check_2 [root@sputnik ashish]# debugfs /dev/sdb1 debugfs 1.41.14 (22-Dec-2010) debugfs: dump_extents check_2 Level Entries Logical Physical Length Flags 0/ 1 1/ 2 0 - 2039 32792 2040 1/ 1 1/340 0 - 5 5771 - 5776 6 1/ 1 2/340 6 - 11 5783 - 5788 6 <------- continue like wise till 340 -------------> 1/ 1 340/340 2034 - 2039 9835 - 9840 6 0/ 1 2/ 2 2040 - 2051 5764 12 1/ 1 1/ 2 2040 - 2045 9847 - 9852 6 1/ 1 2/ 2 2046 - 2051 9859 - 9864 6 Step3: Punch hole at offset 4KB and length of hole is also 4KB There is attached fallocate.c [root@sputnik ashish]# ./fallacote.x86 /mnt/check_2 ret = 0 [root@sputnik ashish]# Check extent tree: [root@sputnik ashish]# debugfs /dev/sdb1 debugfs 1.41.14 (22-Dec-2010) debugfs: dump_extents check_2 Level Entries Logical Physical Length Flags 0/ 1 1/ 3 0 - 5 32792 6 1/ 1 1/ 2 0 - 1 5771 - 5772 2 1/ 1 2/ 2 2 - 5 5773 - 5776 4 0/ 1 2/ 3 6 - 2039 9871 2034 1/ 1 1/339 6 - 11 5783 - 5788 6 <------- continue like wise till 339 -------------> 1/ 1 339/339 2034 - 2039 9835 - 9840 6 0/ 1 3/ 3 2040 - 2051 5764 12 1/ 1 1/ 2 2040 - 2045 9847 - 9852 6 1/ 1 2/ 2 2046 - 2051 9859 - 9864 6 It is clearly visible that punching hole just split the first extent into 2 but failed to remove the required blocks. Step4: To cross check, take diff of 2 files. [root@sputnik ashish]# diff check_1 /mnt/check_2 [root@sputnik ashish]# The 2 files are exactly same. After applying this patch, correct results will be observed. On Mon, Jul 2, 2012 at 2:42 PM, Lukáš Czerner <lczerner@xxxxxxxxxx> wrote: > On Mon, 2 Jul 2012, Ashish Sangwan wrote: > >> Date: Mon, 2 Jul 2012 11:03:26 +0530 >> From: Ashish Sangwan <ashishsangwan2@xxxxxxxxx> >> To: sandeen@xxxxxxxxxx, Lukáš Czerner <lczerner@xxxxxxxxxx>, >> Ted Tso <tytso@xxxxxxx> >> Cc: linux-kernel@xxxxxxxxxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx, >> Namjae Jeon <linkinjeon@xxxxxxxxx> >> Subject: Re: [PATCH v2] ext4: fix hole punch failure when depth is greater >> than 0 >> >> Hi Ted, Lukas, Eric, >> >> Did any of you get a chance to look at it? > > I am sorry for the delay. I have been trying to reproduce this > problem without any success so far. But is was on ppc64 machine, so > I'll try that on x86_64 and then review the patch. > > Thanks! > -Lukas > >> >> On Fri, Jun 22, 2012 at 6:19 AM, Namjae Jeon <linkinjeon@xxxxxxxxx> wrote: >> > Hi. Eric. >> > >> > This is the patch for punch hole issue. >> > >> > Thanks. >> > >>
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#define FALLOC_FL_PUNCH_HOLE 0x02
#define FALLOC_FL_KEEP_SIZE 0X01
int main(int argc, char **argv)
{
int fd;
int mode = 0;
int ret = 0;
if (argc < 2) {
_exit(1);
}
mode = (mode | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE);
if ((fd = open(argv[1], O_RDWR)) < 0) {
fprintf(stderr, "Cannot open file %s\n", argv[1]);
_exit(1);
}
ret= fallocate(fd,mode,4096,4096);
if( ret != 0)
perror("Fallocate fail\n");
printf("ret = %d\n",ret);
close(fd);
return 0;
}
Attachment:
fragment.sh
Description: Bourne shell script
