[PATCH] xfs: use tr_qm_dqalloc log reservation for dquot alloc

[Brian Foster <bfoster@xxxxxxxxxx>]

The dquot allocation path in xfs_qm_dqread() currently uses the
attribute set log reservation, which appears to be incorrect. We
have reports of transaction reservation overruns with the current
code. E.g., a repeated run of xfstests test generic/270 on a 512b
block size fs occassionally produces the following in dmesg:

        XFS (sdN): xlog_write: reservation summary:
          trans type  = QM_DQALLOC (30)
          unit res    = 7080 bytes
          current res = -632 bytes
          total reg   = 0 bytes (o/flow = 0 bytes)
          ophdrs      = 0 (ophdr space = 0 bytes)
          ophdr + reg = 0 bytes
          num regions = 0

        XFS (sdN): xlog_write: reservation ran out. Need to up reservation

The dquot allocation case should consist of a write reservation
(i.e., we are allocating a range of the internal quota file) plus
the size of the actual dquots. We already have a log reservation
definition for this operation (tr_qm_dqalloc). Use it in
xfs_qm_dqread() and update the log reservation calculation function
to use the write res. calculation function rather than reading the
assumed to be pre-calculated value directly.

Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
Hi all,

This issue was reported here:

https://bugzilla.redhat.com/show_bug.cgi?id=1052787

... and the patch seems to address the reservation overrun from my testing.
It also runs through an xfstests regression. Thanks.

Brian

 fs/xfs/xfs_dquot.c      | 2 +-
 fs/xfs/xfs_trans_resv.c | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 6b1e695..06280c6 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -614,7 +614,7 @@ xfs_qm_dqread(
 
        if (flags & XFS_QMOPT_DQALLOC) {
                tp = xfs_trans_alloc(mp, XFS_TRANS_QM_DQALLOC);
-               error = xfs_trans_reserve(tp, &M_RES(mp)->tr_attrsetm,
+               error = xfs_trans_reserve(tp, &M_RES(mp)->tr_qm_dqalloc,
                                          XFS_QM_DQALLOC_SPACE_RES(mp), 0);
                if (error)
                        goto error1;
diff --git a/fs/xfs/xfs_trans_resv.c b/fs/xfs/xfs_trans_resv.c
index 2fd59c0..60b7d40 100644
--- a/fs/xfs/xfs_trans_resv.c
+++ b/fs/xfs/xfs_trans_resv.c
@@ -651,8 +651,7 @@ STATIC uint
 xfs_calc_qm_dqalloc_reservation(
        struct xfs_mount        *mp)
 {
-       ASSERT(M_RES(mp)->tr_write.tr_logres);
-       return M_RES(mp)->tr_write.tr_logres +
+       return xfs_calc_write_reservation(mp) +
                xfs_calc_buf_res(1,
                        XFS_FSB_TO_B(mp, XFS_DQUOT_CLUSTER_SIZE_FSB) - 1);
 }
-- 
1.8.1.4