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authorBrian Foster <bfoster@redhat.com>2018-05-08 02:38:47 +0200
committerDarrick J. Wong <darrick.wong@oracle.com>2018-05-09 19:04:02 +0200
commitf8f2835a9cf300079835e1adb1d90f85033be04c (patch)
tree238c8853b3db62ccea6c56cdfe08035c723d2ae4 /fs/xfs/xfs_trans.c
parentxfs: create agfl block free helper function (diff)
downloadlinux-f8f2835a9cf300079835e1adb1d90f85033be04c.tar.xz
linux-f8f2835a9cf300079835e1adb1d90f85033be04c.zip
xfs: defer agfl block frees when dfops is available
The AGFL fixup code executes before every block allocation/free and rectifies the AGFL based on the current, dynamic allocation requirements of the fs. The AGFL must hold a minimum number of blocks to satisfy a worst case split of the free space btrees caused by the impending allocation operation. The AGFL is also updated to maintain the implicit requirement for a minimum number of free slots to satisfy a worst case join of the free space btrees. Since the AGFL caches individual blocks, AGFL reduction typically involves multiple, single block frees. We've had reports of transaction overrun problems during certain workloads that boil down to AGFL reduction freeing multiple blocks and consuming more space in the log than was reserved for the transaction. Since the objective of freeing AGFL blocks is to ensure free AGFL free slots are available for the upcoming allocation, one way to address this problem is to release surplus blocks from the AGFL immediately but defer the free of those blocks (similar to how file-mapped blocks are unmapped from the file in one transaction and freed via a deferred operation) until the transaction is rolled. This turns AGFL reduction into an operation with predictable log reservation consumption. Add the capability to defer AGFL block frees when a deferred ops list is available to the AGFL fixup code. Add a dfops pointer to the transaction to carry dfops through various contexts to the allocator context. Deferring AGFL frees is conditional behavior based on whether the transaction pointer is populated. The long term objective is to reuse the transaction pointer to clean up all unrelated callchains that pass dfops on the stack along with a transaction and in doing so, consistently defer AGFL blocks from the allocator. A bit of customization is required to handle deferred completion processing because AGFL blocks are accounted against a per-ag reservation pool and AGFL blocks are not inserted into the extent busy list when freed (they are inserted when used and released back to the AGFL). Reuse the majority of the existing deferred extent free infrastructure and customize it appropriately to handle AGFL blocks. Note that this patch only adds infrastructure. It does not change behavior because no callers have been updated to pass ->t_agfl_dfops into the allocation code. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/xfs/xfs_trans.c')
-rw-r--r--fs/xfs/xfs_trans.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index d6d8f9d129a7..06adb1a3e31f 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -31,6 +31,7 @@
#include "xfs_log.h"
#include "xfs_trace.h"
#include "xfs_error.h"
+#include "xfs_defer.h"
kmem_zone_t *xfs_trans_zone;
kmem_zone_t *xfs_log_item_desc_zone;
@@ -94,11 +95,11 @@ xfs_trans_free(
* blocks. Locks and log items, however, are no inherited. They must
* be added to the new transaction explicitly.
*/
-STATIC xfs_trans_t *
+STATIC struct xfs_trans *
xfs_trans_dup(
- xfs_trans_t *tp)
+ struct xfs_trans *tp)
{
- xfs_trans_t *ntp;
+ struct xfs_trans *ntp;
ntp = kmem_zone_zalloc(xfs_trans_zone, KM_SLEEP);
@@ -127,6 +128,7 @@ xfs_trans_dup(
ntp->t_rtx_res = tp->t_rtx_res - tp->t_rtx_res_used;
tp->t_rtx_res = tp->t_rtx_res_used;
ntp->t_pflags = tp->t_pflags;
+ ntp->t_agfl_dfops = tp->t_agfl_dfops;
xfs_trans_dup_dqinfo(tp, ntp);
@@ -936,6 +938,9 @@ __xfs_trans_commit(
int error = 0;
int sync = tp->t_flags & XFS_TRANS_SYNC;
+ ASSERT(!tp->t_agfl_dfops ||
+ !xfs_defer_has_unfinished_work(tp->t_agfl_dfops) || regrant);
+
/*
* If there is nothing to be logged by the transaction,
* then unlock all of the items associated with the