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

Dhruvesh Rathore
2015-01-29T13:23:08Z

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@outlook.com>
Signed-off-by: Amey Ruikar <ameyruikar@yahoo.com>
Signed-off-by: Somdeep Dey <somdeepdey10@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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