xfs: use per-AG reservations for the finobt
Currently we try to rely on the global reserved block pool for block
allocations for the free inode btree, but I have customer reports
(fairly complex workload, need to find an easier reproducer) where that
is not enough as the AG where we free an inode that requires a new
finobt block is entirely full. This causes us to cancel a dirty
transaction and thus a file system shutdown.
I think the right way to guard against this is to treat the finot the same
way as the refcount btree and have a per-AG reservations for the possible
worst case size of it, and the patch below implements that.
Note that this could increase mount times with large finobt trees. In
an ideal world we would have added a field for the number of finobt
fields to the AGI, similar to what we did for the refcount blocks.
We should do add it next time we rev the AGI or AGF format by adding
new fields.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c
index 94234bf..33db69b 100644
--- a/fs/xfs/libxfs/xfs_ag_resv.c
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -39,6 +39,7 @@
#include "xfs_rmap_btree.h"
#include "xfs_btree.h"
#include "xfs_refcount_btree.h"
+#include "xfs_ialloc_btree.h"
/*
* Per-AG Block Reservations
@@ -210,6 +211,9 @@ __xfs_ag_resv_init(
if (error) {
trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
error, _RET_IP_);
+ xfs_warn(mp,
+"Per-AG reservation for AG %u failed. Filesystem may run out of space.",
+ pag->pag_agno);
return error;
}
@@ -228,6 +232,8 @@ int
xfs_ag_resv_init(
struct xfs_perag *pag)
{
+ struct xfs_mount *mp = pag->pag_mount;
+ xfs_agnumber_t agno = pag->pag_agno;
xfs_extlen_t ask;
xfs_extlen_t used;
int error = 0;
@@ -236,23 +242,45 @@ xfs_ag_resv_init(
if (pag->pag_meta_resv.ar_asked == 0) {
ask = used = 0;
- error = xfs_refcountbt_calc_reserves(pag->pag_mount,
- pag->pag_agno, &ask, &used);
+ error = xfs_refcountbt_calc_reserves(mp, agno, &ask, &used);
+ if (error)
+ goto out;
+
+ error = xfs_finobt_calc_reserves(mp, agno, &ask, &used);
if (error)
goto out;
error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
ask, used);
- if (error)
- goto out;
+ if (error) {
+ /*
+ * Because we didn't have per-AG reservations when the
+ * finobt feature was added we might not be able to
+ * reserve all needed blocks. Warn and fall back to the
+ * old and potentially buggy code in that case, but
+ * ensure we do have the reservation for the refcountbt.
+ */
+ ask = used = 0;
+
+ mp->m_inotbt_nores = true;
+
+ error = xfs_refcountbt_calc_reserves(mp, agno, &ask,
+ &used);
+ if (error)
+ goto out;
+
+ error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
+ ask, used);
+ if (error)
+ goto out;
+ }
}
/* Create the AGFL metadata reservation */
if (pag->pag_agfl_resv.ar_asked == 0) {
ask = used = 0;
- error = xfs_rmapbt_calc_reserves(pag->pag_mount, pag->pag_agno,
- &ask, &used);
+ error = xfs_rmapbt_calc_reserves(mp, agno, &ask, &used);
if (error)
goto out;
@@ -261,9 +289,16 @@ xfs_ag_resv_init(
goto out;
}
+#ifdef DEBUG
+ /* need to read in the AGF for the ASSERT below to work */
+ error = xfs_alloc_pagf_init(pag->pag_mount, NULL, pag->pag_agno, 0);
+ if (error)
+ return error;
+
ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
xfs_perag_resv(pag, XFS_AG_RESV_AGFL)->ar_reserved <=
pag->pagf_freeblks + pag->pagf_flcount);
+#endif
out:
return error;
}