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. 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
