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authorDarrick J. Wong <darrick.wong@oracle.com>2018-06-21 23:26:56 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2018-06-24 12:00:12 -0700
commitd8cb5e42378918e00eda58792f3ab86dd1e7d214 (patch)
treea6b91979eb68dab9cbfe3415068f8be9b358bfd5
parente53c4b598372001a13901b77649dc1b4afec3e85 (diff)
xfs: fix fdblocks accounting w/ RMAPBT per-AG reservation
In __xfs_ag_resv_init we incorrectly calculate the amount by which to decrease fdblocks when reserving blocks for the rmapbt. Because rmapbt allocations do not decrease fdblocks, we must decrease fdblocks by the entire size of the requested reservation in order to achieve our goal of always having enough free blocks to satisfy an rmapbt expansion. This is in contrast to the refcountbt/finobt, which /do/ subtract from fdblocks whenever they allocate a block. For this allocation type we preserve the existing behavior where we decrease fdblocks only by the requested reservation minus the size of the existing tree. This fixes the problem where the available block counts reported by statfs change across a remount if there had been an rmapbt size change since mount time. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
-rw-r--r--fs/xfs/libxfs/xfs_ag_resv.c31
1 files changed, 27 insertions, 4 deletions
diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c
index 84db76e0e3e3..fecd187fcf2c 100644
--- a/fs/xfs/libxfs/xfs_ag_resv.c
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -157,6 +157,7 @@ __xfs_ag_resv_free(
error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true);
resv->ar_reserved = 0;
resv->ar_asked = 0;
+ resv->ar_orig_reserved = 0;
if (error)
trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno,
@@ -189,13 +190,34 @@ __xfs_ag_resv_init(
struct xfs_mount *mp = pag->pag_mount;
struct xfs_ag_resv *resv;
int error;
- xfs_extlen_t reserved;
+ xfs_extlen_t hidden_space;
if (used > ask)
ask = used;
- reserved = ask - used;
- error = xfs_mod_fdblocks(mp, -(int64_t)reserved, true);
+ switch (type) {
+ case XFS_AG_RESV_RMAPBT:
+ /*
+ * Space taken by the rmapbt is not subtracted from fdblocks
+ * because the rmapbt lives in the free space. Here we must
+ * subtract the entire reservation from fdblocks so that we
+ * always have blocks available for rmapbt expansion.
+ */
+ hidden_space = ask;
+ break;
+ case XFS_AG_RESV_METADATA:
+ /*
+ * Space taken by all other metadata btrees are accounted
+ * on-disk as used space. We therefore only hide the space
+ * that is reserved but not used by the trees.
+ */
+ hidden_space = ask - used;
+ break;
+ default:
+ ASSERT(0);
+ return -EINVAL;
+ }
+ error = xfs_mod_fdblocks(mp, -(int64_t)hidden_space, true);
if (error) {
trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
error, _RET_IP_);
@@ -216,7 +238,8 @@ __xfs_ag_resv_init(
resv = xfs_perag_resv(pag, type);
resv->ar_asked = ask;
- resv->ar_reserved = resv->ar_orig_reserved = reserved;
+ resv->ar_orig_reserved = hidden_space;
+ resv->ar_reserved = ask - used;
trace_xfs_ag_resv_init(pag, type, ask);
return 0;