From d8cb5e42378918e00eda58792f3ab86dd1e7d214 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 21 Jun 2018 23:26:56 -0700 Subject: 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 Reviewed-by: Allison Henderson --- fs/xfs/libxfs/xfs_ag_resv.c | 31 +++++++++++++++++++++++++++---- 1 file 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; -- cgit v1.2.3