On Wed, Jun 3, 2009 at 2:35 AM, Andreas Dilger <adilger@xxxxxxx> wrote: > Can you please provide some more details of the problem this solves. Sorry for the late reply. When used with -v and the targeted file has more than 144 extents(double of the length of fm_extents array provided by buf), filefrag_fiemap loops and calls fiemap ioctl() multiple times to calculate the actual number of extents in a file. Each call to fiemap ioctl() uses fm_start as the starting logical offset. The patch fixes fm_start in each loop( except for the first one) and makes the extent calculation correct for files with more that 144 extents. To produce the problem, first run filefrag -v on a highly fragmented file. Then change the buf size in filefrag_fiemap to make it large enough to have all the extent mapped in a single loop and run filefrag -v after recompiling. The former will produce a much smaller extent count because of the false fm_start used in the loop. And the two will produce different extent output since the 145th extent. BTW, should I resend the patch to include the above explanation? > > On Jun 03, 2009 02:03 +0800, Peng Tao wrote: >> Signed-off-by: Peng Tao <bergwolf@xxxxxxxxx> >> --- >> misc/filefrag.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/misc/filefrag.c b/misc/filefrag.c >> index 6bea2cd..7786646 100644 >> --- a/misc/filefrag.c >> +++ b/misc/filefrag.c >> @@ -239,7 +239,7 @@ int filefrag_fiemap(int fd, int blk_shift, int *num_extents) >> n++; >> } >> >> - fiemap->fm_start += fm_ext[i-1].fe_logical + >> + fiemap->fm_start = fm_ext[i-1].fe_logical + >> fm_ext[i-1].fe_length; >> } while (last == 0); >> >> -- >> 1.6.2.GIT >> >> -- >> 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 > > Cheers, Andreas > -- > Andreas Dilger > Sr. Staff Engineer, Lustre Group > Sun Microsystems of Canada, Inc. > > -- Cheers, Bergwolf -- 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
