On 6/14/12 3:44 AM, Liu Bo wrote:
> filefrag has several bugs:
>
> 1.
> $ touch f1
> $ filefrag f1
> f1: 1 extent found ----> bug!
> $ filefrag -v f1
> Filesystem type is: ef53
> File size of f1 is 0 (0 blocks, blocksize 4096)
> f1: 0 extents found
>
> 2.
> $ truncate -s 1m f2
> $ filefrag f2
> f2: 1 extent found ----> bug!
> $ filefrag -v f2
> Filesystem type is: ef53
> File size of f2 is 1048576 (256 blocks, blocksize 4096)
> f2: 0 extents found
>
> 3.
> $ for i in `seq 11 -2 0`; do dd if=/dev/zero of=f4 bs=4k count=1 seek=$i conv=notrunc oflag=sync &>/dev/null; done
> $ ll f4
> -rw-r--r-- 1 root root 49152 Jun 9 15:09 f4
> $ filefrag f4
> f4: 7 extents found
> $ filefrag -v f4
> Filesystem type is: ef53
> File size of f4 is 49152 (12 blocks, blocksize 4096)
> ext logical physical expected length flags
> 0 1 1109993 1
> 1 3 1109992 1109994 1
> 2 5 1109991 1109993 1
> 3 7 1109990 1109992 1
> 4 9 1109989 1109991 1
> 5 11 1108207 1109990 1 eof
> f4: 7 extents found --------------------------> but we only have 6 extents, bug!
>
> All of these bugs come from the fact that we've made a mistake on calculating
> total extents:
> o we set 1 as default for 'total extents', and this will report 1 extent found
> even when we don't get any extent from fiemap.
> o if our first extent does not start from 0(logical addr), total extents will
> be one more than what it should be.
>
> Signed-off-by: Liu Bo <liubo2009@xxxxxxxxxxxxxx>
Looks right to me. FWIW, there's a Fedora bug open for this, #840848
Maybe another one for merging, Ted?
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
> misc/filefrag.c | 25 ++++++++++---------------
> 1 files changed, 10 insertions(+), 15 deletions(-)
>
> diff --git a/misc/filefrag.c b/misc/filefrag.c
> index 0583e91..af008fb 100644
> --- a/misc/filefrag.c
> +++ b/misc/filefrag.c
> @@ -175,7 +175,7 @@ static int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
> unsigned int i;
> static int fiemap_incompat_printed;
> int fiemap_header_printed = 0;
> - int tot_extents = 1, n = 0;
> + int tot_extents = 0, n = 0;
> int last = 0;
> int rc;
>
> @@ -201,25 +201,17 @@ static int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
> return rc;
> }
>
> + /* If 0 extents are returned, then more ioctls are not needed */
> + if (fiemap->fm_mapped_extents == 0)
> + break;
> +
> if (verbose && !fiemap_header_printed) {
> - /*
> - * No extents on first call?
> - * Skip header and show 0 extents.
> - */
> - if (fiemap->fm_mapped_extents == 0) {
> - *num_extents = 0;
> - goto out;
> - }
> printf(" ext %*s %*s %*s length flags\n", logical_width,
> "logical", physical_width, "physical",
> physical_width, "expected");
> fiemap_header_printed = 1;
> }
>
> - /* If 0 extents are returned, then more ioctls are not needed */
> - if (fiemap->fm_mapped_extents == 0)
> - break;
> -
> for (i = 0; i < fiemap->fm_mapped_extents; i++) {
> __u64 phy_blk, logical_blk;
> unsigned long ext_len;
> @@ -228,10 +220,13 @@ static int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
> ext_len = fm_ext[i].fe_length >> blk_shift;
> logical_blk = fm_ext[i].fe_logical >> blk_shift;
>
> - if (logical_blk && phy_blk != expected)
> + if (logical_blk && phy_blk != expected) {
> tot_extents++;
> - else
> + } else {
> expected = 0;
> + if (!tot_extents)
> + tot_extents = 1;
> + }
> if (verbose)
> print_extent_info(&fm_ext[i], n, expected,
> blk_shift);
>
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