Lol!
Thanks Darrick!
On Fri, Apr 26, 2019 at 6:24 PM Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote:
>
> On Fri, Apr 26, 2019 at 07:13:49PM -0500, Eric Sandeen wrote:
> > On 4/26/19 5:59 PM, Jorge Guerra wrote:
> > > From: Jorge Guerra <jorgeguerra@xxxxxx>
> > >
> > > While running the 'frag' command of 'xfs_db' we noticed that the
> > > tool is not scanning all the files in the file system. We noticed
> > > this when we modified the tool to print the inodes of all the files
> > > scanned. For example:
> > >
> > > $ find /mnt/xfsdisk -type f | wc -l
> > > 1782674
> > > $ xfs_db -r -c frag /dev/sdXX | grep MB | awk '{print $5}' | paste -s -d+ | bc
> > > 656818
> > >
> > > Upon inspecting the code we noticed that the scanfunc_ino function
> > > stops processing a given inode block once it encounters a free leaf.
> > > However, in practice we see that inodes are necessarily always layed
> > > out contiguously on the leaf node. This resulted in the 'frag'
> > > command skipping some valid inodes.
> > >
> > > In this change we modify the scanfunc_ino function to skip freed
> > > inodes. With the change in place we ran the same experiment again
> > > and noticed a more accurate file count:
> > >
> > > $ find /mnt/d0 -type f | wc -l
> > > 1810442
> > > $ xfs_db -r -c frag /dev/sdXX | grep MB | awk '{print $5}' | paste -s -d+ | bc
> > > 1810442
> > >
> > > Signed-off-by: Jorge Guerra <jorgeguerra@xxxxxx>
> >
> > This looks right, but I'll warn you that xfs_db's frag command is largely
> > useless in the first place. ;)
>
> I was looking through the manpages for the part where it says frag is
> useless but couldn't find it. Oh well. :(
>
> Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> --D
>
> >
> > Also, I think:
> >
> > Fixes: 2a5eb70c ("xfs_db: teach the frag command about sparse inode chunks")
> >
> > Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> >
> > Thanks!
> >
> > > ---
> > > db/frag.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/db/frag.c b/db/frag.c
> > > index 5f33cb73..91395234 100644
> > > --- a/db/frag.c
> > > +++ b/db/frag.c
> > > @@ -507,7 +507,7 @@ scanfunc_ino(
> > >
> > > for (j = 0; j < inodes_per_buf; j++) {
> > > if (XFS_INOBT_IS_FREE_DISK(&rp[i], ioff + j))
> > > - goto next_buf;
> > > + continue;
> > > dip = (xfs_dinode_t *)((char *)iocur_top->data +
> > > ((off + j) << mp->m_sb.sb_inodelog));
> > > process_inode(agf, agino + ioff + j, dip);
> > >
--
Jorge E Guerra D
