xfs: use the actual AG length when reserving blocks

We need to use the actual AG length when making per-AG reservations,
since we could otherwise end up reserving more blocks out of the last
AG than there are actual blocks.

Complained-about-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 7 insertions, 7 deletions

diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index de25771764ba..74e5a54bc428 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -550,13 +550,14 @@ xfs_rmapbt_calc_size(
  */
 xfs_extlen_t
 xfs_rmapbt_max_size(
-	struct xfs_mount	*mp)
+	struct xfs_mount	*mp,
+	xfs_agblock_t		agblocks)
 {
 	/* Bail out if we're uninitialized, which can happen in mkfs. */
 	if (mp->m_rmap_mxr[0] == 0)
 		return 0;
 
-	return xfs_rmapbt_calc_size(mp, mp->m_sb.sb_agblocks);
+	return xfs_rmapbt_calc_size(mp, agblocks);
 }
 
 /*
@@ -571,25 +572,24 @@ xfs_rmapbt_calc_reserves(
 {
 	struct xfs_buf		*agbp;
 	struct xfs_agf		*agf;
-	xfs_extlen_t		pool_len;
+	xfs_agblock_t		agblocks;
 	xfs_extlen_t		tree_len;
 	int			error;
 
 	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
 		return 0;
 
-	/* Reserve 1% of the AG or enough for 1 block per record. */
-	pool_len = max(mp->m_sb.sb_agblocks / 100, xfs_rmapbt_max_size(mp));
-	*ask += pool_len;
-
 	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
 	if (error)
 		return error;
 
 	agf = XFS_BUF_TO_AGF(agbp);
+	agblocks = be32_to_cpu(agf->agf_length);
 	tree_len = be32_to_cpu(agf->agf_rmap_blocks);
 	xfs_buf_relse(agbp);
 
+	/* Reserve 1% of the AG or enough for 1 block per record. */
+	*ask += max(agblocks / 100, xfs_rmapbt_max_size(mp, agblocks));
 	*used += tree_len;
 
 	return error;