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);
> >
