[PATCH 1/9] xfs: fix reflink quota reservation accounting error

Darrick J. Wong
2020-06-25T01:19:55Z

From: Darrick J. Wong <darrick.wong@oracle.com>

Quota reservations are supposed to account for the blocks that might be
allocated due to a bmap btree split. Reflink doesn't do this, so fix
this to make the quota accounting more accurate before we start
rearranging things.

Fixes: 862bb360ef56 ("xfs: reflink extents from one file to another")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/xfs_reflink.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 107bf2a2f344..d89201d40891 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1003,6 +1003,7 @@ xfs_reflink_remap_extent(
xfs_filblks_t rlen;
xfs_filblks_t unmap_len;
xfs_off_t newlen;
+ int64_t qres;
int error;

unmap_len = irec->br_startoff + irec->br_blockcount - destoff;
@@ -1025,13 +1026,19 @@ xfs_reflink_remap_extent(
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, 0);

- /* If we're not just clearing space, then do we have enough quota? */
- if (real_extent) {
- error = xfs_trans_reserve_quota_nblks(tp, ip,
- irec->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS);
- if (error)
- goto out_cancel;
- }
+ /*
+ * Reserve quota for this operation. We don't know if the first unmap
+ * in the dest file will cause a bmap btree split, so we always reserve
+ * at least enough blocks for that split. If the extent being mapped
+ * in is written, we need to reserve quota for that too.
+ */
+ qres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
+ if (real_extent)
+ qres += irec->br_blockcount;
+ error = xfs_trans_reserve_quota_nblks(tp, ip, qres, 0,
+ XFS_QMOPT_RES_REGBLKS);
+ if (error)
+ goto out_cancel;

trace_xfs_reflink_remap(ip, irec->br_startoff,
irec->br_blockcount, irec->br_startblock);