[PATCH 1/4] xfs: Accounting for AGFL blocks in xfs_spaceman

[Dhruvesh Rathore]

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

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Signed-off-by: Dhruvesh Rathore <dhruvesh_r at outlook.com>
Signed-off-by: Amey Ruikar <ameyruikar at yahoo.com>
Signed-off-by: Somdeep Dey <somdeepdey10 at gmail.com>
---
fs/xfs/libxfs/xfs_alloc.c | 69 ++++++++++++++++
1 file changed, 69 insertions(+)

--- a/fs/xfs/libxfs/xfs_alloc.c	2015-01-29 09:07:07.116439198 +0530
+++ b/fs/xfs/libxfs/xfs_alloc.c	2015-01-29 09:06:39.664440229 +0530

@@ -2698,6 +2698,71 @@
 }
 
 
+/*
+ * 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_agblock_t		sagbno,
+	xfs_agblock_t		eagbno)
+{
+	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_agblock_t	fbno;
+		xfs_extlen_t	flen;
+		xfs_daddr_t	dbno;
+		xfs_fileoff_t	dlen;	
+		int		flags = 0;
+
+		fbno = be32_to_cpu(agfl_bno[i]);
+		flen = 1;
+
+		/* range check - must be wholly withing requested range */
+		if (fbno < sagbno ||
+			(eagbno != NULLAGBLOCK && fbno + flen > eagbno)) {
+		xfs_warn(mp, "10: %d/%d, %d/%d", sagbno, eagbno, fbno, flen);
+			continue;
+		}
+
+		/*
+		 * 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, fbno);
+		dlen = XFS_FSB_TO_BB(mp, flen);
+
+		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.
@@ -2804,6 +2869,10 @@
 		}
 		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, sagbno,
+						agno == eagno ? eagbno : NULLAGBLOCK);
+
 		if (!bycnt) {
 			/*
 			 * if we are doing a bno ordered lookup, we can just

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