xfs: Accounting for AGFL blocks in xfs_spaceman

The xfs_spaceman utility previously failed to account for AGFL blocks. Old output (Before changes).

$ sudo xfs_spaceman -c "freesp" /media/xfs
   from      to extents  blocks    pct
   1024    2047       1    1262   0.04
   4096    8191       1    5126   0.15
   8192   16383       3   35344   1.05
  32768   65535       1   43989   1.31
 262144  524287       3 1334894  39.78
 524288  967428       2 1934840  57.66

As you can see the AGFL blocks were unaccounted (4 per AG, and there were 4 AGs in this filesystem).

This patch is concerned with adding a new function which will walk the free extents in AGFL and account for these AGFL blocks, while file system scanning.

New output (After implementing this patch).

$ uname -a
Linux dhruv-MacBookAir 3.18.0-rc7+ #3 SMP Thu Dec 25 15:29:59 IST 2014 x86_64 x86_64 x86_64 GNU/Linux
$ sudo xfs_spaceman -V
xfs_spaceman version 3.2.2
$ sudo xfs_spaceman -c "freesp" /media/xfs
   from      to extents  blocks    pct
      1       1      16      16   0.00
   1024    2047       1    1262   0.04
   4096    8191       1    5126   0.15
   8192   16383       3   35344   1.05
  32768   65535       1   43989   1.31
 262144  524287       3 1334894  39.78
 524288  967428       2 1934840  57.66

-------------------------------------------------------------------------------------------

---
fs/xfs/libxfs/xfs_alloc.c | 53 ++++++++++++++

1 file changed, 53 insertions(+)

--- a/fs/xfs/libxfs/xfs_alloc.c 2015-01-28 15:25:02.396172903 +0530
+++ b/fs/xfs/libxfs/xfs_alloc.c 2015-01-28 15:13:46.936198272 +0530

@@ -2697,6 +2697,56 @@

}

+/*
+ * When we map free space we need to take into account the blocks
+ * that are indexed by the AGFL. They aren't found by walking the
+ * free space btrees, so we have to walk each AGFL to find them.
+ */
+static int
+xfs_alloc_agfl_freespace_map(
+ struct xfs_mount *mp,
+ struct xfs_agf *agf,
+ struct fiemap_extent_info *fieinfo,
+ xfs_agnumber_t agno)
+{
+ xfs_buf_t *agflbp;
+ __be32 *agfl_bno;
+ int i;
+ int error = 0;
+
+ error = xfs_alloc_read_agfl(mp, NULL, be32_to_cpu(agf->agf_seqno), &agflbp);
+
+ if (error)
+ return error;
+
+ agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agflbp);
+
+ for(i = be32_to_cpu(agf->agf_flfirst);
+ i <= be32_to_cpu(agf->agf_fllast);) {
+
+ xfs_daddr_t dbno;
+ xfs_fileoff_t dlen;
+ int flags = 0;
+
+ /*
+ * Use daddr format for all range/len calculations as that is
+ * the format the range/len variables are supplied in by
+ * userspace.
+ */
+
+ dbno = XFS_AGB_TO_DADDR(mp, agno, be32_to_cpu(agfl_bno[i]));
+ dlen = XFS_FSB_TO_BB(mp, 1);
+
+ error = -fiemap_fill_next_extent(fieinfo,BBTOB(dbno),
+ BBTOB(dbno), BBTOB(dlen), flags);
+ if (error)
+ break;
+ if (++i == XFS_AGFL_SIZE(mp))
+ i = 0;
+ }
+ xfs_buf_relse(agflbp);
+ return error;
+}

/*
* Map the freespace from the requested range in the requested order.
@@ -2803,6 +2853,9 @@
}
XFS_WANT_CORRUPTED_GOTO(i == 1, del_cursor);

+ /* Account for the free blocks in AGFL */
+ error = xfs_alloc_agfl_freespace_map(mp, XFS_BUF_TO_AGF(agbp), fieinfo, agno);
+
if (!bycnt) {
/*
* if we are doing a bno ordered lookup, we can just

-------------------------------------------------------------------------------------------

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