Re: [PATCH v2] xfs_scrub: don't use statvfs to collect filesystem summary counts

Brian Foster
2020-10-09T11:18:22Z

On Mon, Oct 05, 2020 at 09:37:37AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> The function scrub_scan_estimate_blocks naÃ¯vely uses the statvfs counts
> to estimate the size and free blocks on the data volume. Unfortunately,
> it fails to account for the fact that statvfs can return the size and
> free counts for the realtime volume if the root directory has the
> rtinherit flag set, which leads to phase 7 reporting totally absurd
> quantities.
>
> Eric pointed out a further problem with statvfs, which is that the file
> counts are clamped to the current user's project quota inode limits.
> Therefore, we must not use statvfs for querying the filesystem summary
> counts.
>
> The XFS_IOC_FSCOUNTS ioctl returns all the data we need, so use that
> instead.
>
> Fixes: 604dd3345f35 ("xfs_scrub: filesystem counter collection functions")
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> v2: drop statvfs entirely
> ---

This doesn't seem to apply to for-next..?

Brian

> scrub/fscounters.c | 27 ++++-----------------------
> 1 file changed, 4 insertions(+), 23 deletions(-)
>
> diff --git a/scrub/fscounters.c b/scrub/fscounters.c
> index f9d64f8c008f..e9901fcdf6df 100644
> --- a/scrub/fscounters.c
> +++ b/scrub/fscounters.c
> @@ -130,38 +130,19 @@ scrub_scan_estimate_blocks(
> unsigned long long *f_free)
> {
> struct xfs_fsop_counts fc;
> - struct xfs_fsop_resblks rb;
> - struct statvfs sfs;
> int error;
>
> - /* Grab the fstatvfs counters, since it has to report accurately. */
> - error = fstatvfs(ctx->mnt.fd, &sfs);
> - if (error)
> - return errno;
> -
> /* Fetch the filesystem counters. */
> error = ioctl(ctx->mnt.fd, XFS_IOC_FSCOUNTS, &fc);
> if (error)
> return errno;
>
> - /*
> - * XFS reserves some blocks to prevent hard ENOSPC, so add those
> - * blocks back to the free data counts.
> - */
> - error = ioctl(ctx->mnt.fd, XFS_IOC_GET_RESBLKS, &rb);
> - if (error)
> - return errno;
> -
> - sfs.f_bfree += rb.resblks_avail;
> -
> - *d_blocks = sfs.f_blocks;
> - if (ctx->mnt.fsgeom.logstart > 0)
> - *d_blocks += ctx->mnt.fsgeom.logblocks;
> - *d_bfree = sfs.f_bfree;
> + *d_blocks = ctx->mnt.fsgeom.datablocks;
> + *d_bfree = fc.freedata;
> *r_blocks = ctx->mnt.fsgeom.rtblocks;
> *r_bfree = fc.freertx;
> - *f_files = sfs.f_files;
> - *f_free = sfs.f_ffree;
> + *f_files = fc.allocino;
> + *f_free = fc.freeino;
>
> return 0;
> }
>