[PATCH 45/47] xfs: don't update rmapbt when fixing agfl

Darrick J. Wong
2016-07-21T05:01:12Z

Allow a caller of xfs_alloc_fix_freelist to disable rmapbt updates
when fixing the AG freelist. xfs_repair needs this during phase 5
to be able to adjust the freelist while it's reconstructing the rmap
btree; the missing entries will be added back at the very end of
phase 5 once the AGFL contents settle down.

v2: Explicitly skip the rmap owner update since we no longer accept
owner == 0 for "don't update rmap".

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/libxfs/xfs_alloc.c | 18 ++++++++++++++----
fs/xfs/libxfs/xfs_alloc.h | 3 +++
2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 73ab1ea..a0dc299 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2090,9 +2090,21 @@ xfs_alloc_fix_freelist(
* anything other than extra overhead when we need to put more blocks
* back on the free list? Maybe we should only do this when space is
* getting low or the AGFL is more than half full?
+ *
+ * The NOSHRINK flag prevents the AGFL from being shrunk if it's too
+ * big; the NORMAP flag prevents AGFL expand/shrink operations from
+ * updating the rmapbt. Both flags are used in xfs_repair while we're
+ * rebuilding the rmapbt, and neither are used by the kernel. They're
+ * both required to ensure that rmaps are correctly recorded for the
+ * regenerated AGFL, bnobt, and cntbt. See repair/phase5.c and
+ * repair/rmap.c in xfsprogs for details.
*/
- xfs_rmap_ag_owner(&targs.oinfo, XFS_RMAP_OWN_AG);
- while (pag->pagf_flcount > need) {
+ memset(&targs, 0, sizeof(targs));
+ if (flags & XFS_ALLOC_FLAG_NORMAP)
+ xfs_rmap_skip_owner_update(&targs.oinfo);
+ else
+ xfs_rmap_ag_owner(&targs.oinfo, XFS_RMAP_OWN_AG);
+ while (!(flags & XFS_ALLOC_FLAG_NOSHRINK) && pag->pagf_flcount > need) {
struct xfs_buf *bp;

error = xfs_alloc_get_freelist(tp, agbp, &bno, 0);
@@ -2106,10 +2118,8 @@ xfs_alloc_fix_freelist(
xfs_trans_binval(tp, bp);
}

- memset(&targs, 0, sizeof(targs));
targs.tp = tp;
targs.mp = mp;
- xfs_rmap_ag_owner(&targs.oinfo, XFS_RMAP_OWN_AG);
targs.agbp = agbp;
targs.agno = args->agno;
targs.alignment = targs.minlen = targs.prod = targs.isfl = 1;
diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
index 360f9e4..6fe2d6b 100644
--- a/fs/xfs/libxfs/xfs_alloc.h
+++ b/fs/xfs/libxfs/xfs_alloc.h
@@ -54,6 +54,9 @@ typedef unsigned int xfs_alloctype_t;
*/
#define XFS_ALLOC_FLAG_TRYLOCK 0x00000001 /* use trylock for buffer locking */
#define XFS_ALLOC_FLAG_FREEING 0x00000002 /* indicate caller is freeing extents*/
+#define XFS_ALLOC_FLAG_NORMAP 0x00000004 /* don't modify the rmapbt */
+#define XFS_ALLOC_FLAG_NOSHRINK 0x00000008 /* don't shrink the freelist */
+

/*
* Argument structure for xfs_alloc routines.