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From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: david@fromorbit.com, darrick.wong@oracle.com
Cc: linux-xfs@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	xfs@oss.sgi.com
Subject: [PATCH 35/71] xfs: preallocate blocks for worst-case btree expansion
Date: Thu, 25 Aug 2016 16:50:19 -0700	[thread overview]
Message-ID: <147216901995.4420.9308541290373322813.stgit@birch.djwong.org> (raw)
In-Reply-To: <147216879156.4420.2446767701729565218.stgit@birch.djwong.org>

To gracefully handle the situation where a CoW operation turns a
single refcount extent into a lot of tiny ones and then run out of
space when a tree split has to happen, use the per-AG reserved block
pool to pre-allocate all the space we'll ever need for a maximal
btree.  For a 4K block size, this only costs an overhead of 0.3% of
available disk space.

When reflink is enabled, we have an unfortunate problem with rmap --
since we can share a block billions of times, this means that the
reverse mapping btree can expand basically infinitely.  When an AG is
so full that there are no free blocks with which to expand the rmapbt,
the filesystem will shut down hard.

This is rather annoying to the user, so use the AG reservation code to
reserve a "reasonable" amount of space for rmap.  We'll prevent
reflinks and CoW operations if we think we're getting close to
exhausting an AG's free space rather than shutting down, but this
permanent reservation should be enough for "most" users.  Hopefully.

v2: Simplify the return value from xfs_perag_pool_free_block to a bool
so that we can easily call xfs_trans_binval for both the per-AG pool
and the real freeing case.  Without this we fail to invalidate the
btree buffer and will trip over the write verifier on a shrinking
refcount btree.

v3: Convert to the new per-AG reservation code.

v4: Combine this patch with the one that adds the rmapbt reservation,
since the rmapbt reservation is only needed for reflink filesystems.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
[hch@lst.de: ensure that we invalidate the freed btree buffer]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 libxfs/xfs_ag_resv.c        |   11 ++++++++
 libxfs/xfs_refcount_btree.c |   45 ++++++++++++++++++++++++++++++--
 libxfs/xfs_refcount_btree.h |    3 ++
 libxfs/xfs_rmap_btree.c     |   60 +++++++++++++++++++++++++++++++++++++++++++
 libxfs/xfs_rmap_btree.h     |    7 +++++
 5 files changed, 123 insertions(+), 3 deletions(-)


diff --git a/libxfs/xfs_ag_resv.c b/libxfs/xfs_ag_resv.c
index af69235..9d338bd 100644
--- a/libxfs/xfs_ag_resv.c
+++ b/libxfs/xfs_ag_resv.c
@@ -37,6 +37,7 @@
 #include "xfs_trans_space.h"
 #include "xfs_rmap_btree.h"
 #include "xfs_btree.h"
+#include "xfs_refcount_btree.h"
 
 /*
  * Per-AG Block Reservations
@@ -229,6 +230,11 @@ xfs_ag_resv_init(
 	/* Create the metadata reservation. */
 	ask = used = 0;
 
+	err2 = xfs_refcountbt_calc_reserves(pag->pag_mount, pag->pag_agno,
+			&ask, &used);
+	if (err2 && !error)
+		error = err2;
+
 	err2 = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA, ask, used);
 	if (err2 && !error)
 		error = err2;
@@ -240,6 +246,11 @@ init_agfl:
 	/* Create the AGFL metadata reservation */
 	ask = used = 0;
 
+	err2 = xfs_rmapbt_calc_reserves(pag->pag_mount, pag->pag_agno,
+			&ask, &used);
+	if (err2 && !error)
+		error = err2;
+
 	err2 = __xfs_ag_resv_init(pag, XFS_AG_RESV_AGFL, ask, used);
 	if (err2 && !error)
 		error = err2;
diff --git a/libxfs/xfs_refcount_btree.c b/libxfs/xfs_refcount_btree.c
index 568a2f8..d2dbdbd 100644
--- a/libxfs/xfs_refcount_btree.c
+++ b/libxfs/xfs_refcount_btree.c
@@ -78,6 +78,8 @@ xfs_refcountbt_alloc_block(
 	struct xfs_alloc_arg	args;		/* block allocation args */
 	int			error;		/* error return value */
 
+	XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+
 	memset(&args, 0, sizeof(args));
 	args.tp = cur->bc_tp;
 	args.mp = cur->bc_mp;
@@ -87,6 +89,7 @@ xfs_refcountbt_alloc_block(
 	args.firstblock = args.fsbno;
 	xfs_rmap_ag_owner(&args.oinfo, XFS_RMAP_OWN_REFC);
 	args.minlen = args.maxlen = args.prod = 1;
+	args.resv = XFS_AG_RESV_METADATA;
 
 	error = xfs_alloc_vextent(&args);
 	if (error)
@@ -124,16 +127,19 @@ xfs_refcountbt_free_block(
 	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agbp);
 	xfs_fsblock_t		fsbno = XFS_DADDR_TO_FSB(mp, XFS_BUF_ADDR(bp));
 	struct xfs_owner_info	oinfo;
+	int			error;
 
 	trace_xfs_refcountbt_free_block(cur->bc_mp, cur->bc_private.a.agno,
 			XFS_FSB_TO_AGBNO(cur->bc_mp, fsbno), 1);
 	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_REFC);
 	be32_add_cpu(&agf->agf_refcount_blocks, -1);
 	xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_REFCOUNT_BLOCKS);
-	xfs_bmap_add_free(mp, cur->bc_private.a.dfops, fsbno, 1,
-			&oinfo);
+	error = xfs_free_extent(cur->bc_tp, fsbno, 1, &oinfo,
+			XFS_AG_RESV_METADATA);
+	if (error)
+		return error;
 
-	return 0;
+	return error;
 }
 
 STATIC int
@@ -403,3 +409,36 @@ xfs_refcountbt_max_size(
 
 	return xfs_refcountbt_calc_size(mp, mp->m_sb.sb_agblocks);
 }
+
+/*
+ * Figure out how many blocks to reserve and how many are used by this btree.
+ */
+int
+xfs_refcountbt_calc_reserves(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	xfs_extlen_t		*ask,
+	xfs_extlen_t		*used)
+{
+	struct xfs_buf		*agbp;
+	struct xfs_agf		*agf;
+	xfs_extlen_t		tree_len;
+	int			error;
+
+	if (!xfs_sb_version_hasreflink(&mp->m_sb))
+		return 0;
+
+	*ask += xfs_refcountbt_max_size(mp);
+
+	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
+	if (error)
+		return error;
+
+	agf = XFS_BUF_TO_AGF(agbp);
+	tree_len = be32_to_cpu(agf->agf_refcount_blocks);
+	xfs_buf_relse(agbp);
+
+	*used += tree_len;
+
+	return error;
+}
diff --git a/libxfs/xfs_refcount_btree.h b/libxfs/xfs_refcount_btree.h
index 780b02f..3be7768 100644
--- a/libxfs/xfs_refcount_btree.h
+++ b/libxfs/xfs_refcount_btree.h
@@ -68,4 +68,7 @@ extern xfs_extlen_t xfs_refcountbt_calc_size(struct xfs_mount *mp,
 		unsigned long long len);
 extern xfs_extlen_t xfs_refcountbt_max_size(struct xfs_mount *mp);
 
+extern int xfs_refcountbt_calc_reserves(struct xfs_mount *mp,
+		xfs_agnumber_t agno, xfs_extlen_t *ask, xfs_extlen_t *used);
+
 #endif	/* __XFS_REFCOUNT_BTREE_H__ */
diff --git a/libxfs/xfs_rmap_btree.c b/libxfs/xfs_rmap_btree.c
index 29a4dd6..02ceace 100644
--- a/libxfs/xfs_rmap_btree.c
+++ b/libxfs/xfs_rmap_btree.c
@@ -33,6 +33,7 @@
 #include "xfs_rmap_btree.h"
 #include "xfs_trace.h"
 #include "xfs_cksum.h"
+#include "xfs_ag_resv.h"
 
 /*
  * Reverse map btree.
@@ -516,3 +517,62 @@ xfs_rmapbt_compute_maxlevels(
 		mp->m_rmap_maxlevels = xfs_btree_compute_maxlevels(mp,
 				mp->m_rmap_mnr, mp->m_sb.sb_agblocks);
 }
+
+/* Calculate the refcount btree size for some records. */
+xfs_extlen_t
+xfs_rmapbt_calc_size(
+	struct xfs_mount	*mp,
+	unsigned long long	len)
+{
+	return xfs_btree_calc_size(mp, mp->m_rmap_mnr, len);
+}
+
+/*
+ * Calculate the maximum refcount btree size.
+ */
+xfs_extlen_t
+xfs_rmapbt_max_size(
+	struct xfs_mount	*mp)
+{
+	/* Bail out if we're uninitialized, which can happen in mkfs. */
+	if (mp->m_rmap_mxr[0] == 0)
+		return 0;
+
+	return xfs_rmapbt_calc_size(mp, mp->m_sb.sb_agblocks);
+}
+
+/*
+ * Figure out how many blocks to reserve and how many are used by this btree.
+ */
+int
+xfs_rmapbt_calc_reserves(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	xfs_extlen_t		*ask,
+	xfs_extlen_t		*used)
+{
+	struct xfs_buf		*agbp;
+	struct xfs_agf		*agf;
+	xfs_extlen_t		pool_len;
+	xfs_extlen_t		tree_len;
+	int			error;
+
+	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+		return 0;
+
+	/* Reserve 1% of the AG or enough for 1 block per record. */
+	pool_len = max(mp->m_sb.sb_agblocks / 100, xfs_rmapbt_max_size(mp));
+	*ask += pool_len;
+
+	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
+	if (error)
+		return error;
+
+	agf = XFS_BUF_TO_AGF(agbp);
+	tree_len = be32_to_cpu(agf->agf_rmap_blocks);
+	xfs_buf_relse(agbp);
+
+	*used += tree_len;
+
+	return error;
+}
diff --git a/libxfs/xfs_rmap_btree.h b/libxfs/xfs_rmap_btree.h
index 5ff9cfa..f3137a3 100644
--- a/libxfs/xfs_rmap_btree.h
+++ b/libxfs/xfs_rmap_btree.h
@@ -58,4 +58,11 @@ struct xfs_btree_cur *xfs_rmapbt_init_cursor(struct xfs_mount *mp,
 int xfs_rmapbt_maxrecs(struct xfs_mount *mp, int blocklen, int leaf);
 extern void xfs_rmapbt_compute_maxlevels(struct xfs_mount *mp);
 
+extern xfs_extlen_t xfs_rmapbt_calc_size(struct xfs_mount *mp,
+		unsigned long long len);
+extern xfs_extlen_t xfs_rmapbt_max_size(struct xfs_mount *mp);
+
+extern int xfs_rmapbt_calc_reserves(struct xfs_mount *mp,
+		xfs_agnumber_t agno, xfs_extlen_t *ask, xfs_extlen_t *used);
+
 #endif /* __XFS_RMAP_BTREE_H__ */

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  parent reply	other threads:[~2016-08-25 23:50 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-25 23:46 [PATCH v8 00/71] xfsprogs: add reflink and dedupe support Darrick J. Wong
2016-08-25 23:46 ` [PATCH 01/71] xfs: remove xfs_btree_bigkey Darrick J. Wong
2016-08-25 23:46 ` [PATCH 02/71] xfs: create a standard btree size calculator code Darrick J. Wong
2016-08-25 23:46 ` [PATCH 03/71] xfs: count the blocks in a btree Darrick J. Wong
2016-08-25 23:46 ` [PATCH 04/71] xfs: defer should allow ->finish_item to request a new transaction Darrick J. Wong
2016-08-25 23:47 ` [PATCH 05/71] xfs: set up per-AG free space reservations Darrick J. Wong
2016-08-25 23:47 ` [PATCH 06/71] xfs: introduce refcount btree definitions Darrick J. Wong
2016-08-25 23:47 ` [PATCH 07/71] xfs: add refcount btree stats infrastructure Darrick J. Wong
2016-08-25 23:47 ` [PATCH 08/71] xfs: refcount btree add more reserved blocks Darrick J. Wong
2016-08-25 23:47 ` [PATCH 09/71] xfs: define the on-disk refcount btree format Darrick J. Wong
2016-08-25 23:47 ` [PATCH 10/71] xfs: account for the refcount btree in the alloc/free log reservation Darrick J. Wong
2016-08-25 23:47 ` [PATCH 11/71] xfs: add refcount btree operations Darrick J. Wong
2016-08-25 23:47 ` [PATCH 12/71] xfs: create refcount update intent log items Darrick J. Wong
2016-08-25 23:47 ` [PATCH 13/71] xfs: log refcount intent items Darrick J. Wong
2016-08-25 23:48 ` [PATCH 14/71] xfs: adjust refcount of an extent of blocks in refcount btree Darrick J. Wong
2016-08-25 23:48 ` [PATCH 15/71] xfs: connect refcount adjust functions to upper layers Darrick J. Wong
2016-08-25 23:48 ` [PATCH 16/71] xfs: adjust refcount when unmapping file blocks Darrick J. Wong
2016-08-25 23:48 ` [PATCH 17/71] xfs: refcount btree requires more reserved space Darrick J. Wong
2016-08-25 23:48 ` [PATCH 18/71] xfs: introduce reflink utility functions Darrick J. Wong
2016-08-25 23:48 ` [PATCH 19/71] xfs: create bmbt update intent log items Darrick J. Wong
2016-08-25 23:48 ` [PATCH 20/71] xfs: log bmap intent items Darrick J. Wong
2016-08-25 23:48 ` [PATCH 21/71] xfs: map an inode's offset to an exact physical block Darrick J. Wong
2016-08-25 23:48 ` [PATCH 22/71] xfs: pass bmapi flags through to bmap_del_extent Darrick J. Wong
2016-08-25 23:48 ` [PATCH 23/71] xfs: implement deferred bmbt map/unmap operations Darrick J. Wong
2016-08-25 23:49 ` [PATCH 24/71] xfs: return work remaining at the end of a bunmapi operation Darrick J. Wong
2016-08-25 23:49 ` [PATCH 25/71] xfs: add reflink feature flag to geometry Darrick J. Wong
2016-08-25 23:49 ` [PATCH 26/71] xfs: don't allow reflinked dir/dev/fifo/socket/pipe files Darrick J. Wong
2016-08-25 23:49 ` [PATCH 27/71] xfs: introduce the CoW fork Darrick J. Wong
2016-08-25 23:49 ` [PATCH 28/71] xfs: support bmapping delalloc extents in " Darrick J. Wong
2016-08-25 23:49 ` [PATCH 29/71] xfs: support allocating delayed extents in " Darrick J. Wong
2016-08-25 23:49 ` [PATCH 30/71] xfs: support removing extents from " Darrick J. Wong
2016-08-25 23:49 ` [PATCH 31/71] xfs: store in-progress CoW allocations in the refcount btree Darrick J. Wong
2016-08-25 23:49 ` [PATCH 32/71] xfs: teach get_bmapx and fiemap about shared extents and the CoW fork Darrick J. Wong
2016-08-25 23:50 ` [PATCH 33/71] xfs: support FS_XFLAG_REFLINK on reflink filesystems Darrick J. Wong
2016-08-25 23:50 ` [PATCH 34/71] xfs: create a separate cow extent size hint for the allocator Darrick J. Wong
2016-08-25 23:50 ` Darrick J. Wong [this message]
2016-08-25 23:50 ` [PATCH 36/71] xfs: try other AGs to allocate a BMBT block Darrick J. Wong
2016-08-25 23:50 ` [PATCH 37/71] xfs: increase log reservations for reflink Darrick J. Wong
2016-08-25 23:50 ` [PATCH 38/71] xfs: add shared rmap map/unmap/convert log item types Darrick J. Wong
2016-08-25 23:50 ` [PATCH 39/71] xfs: use interval query for rmap map and unmap operations on shared files Darrick J. Wong
2016-08-25 23:50 ` [PATCH 40/71] xfs: convert unwritten status of shared-extent reverse mappings " Darrick J. Wong
2016-08-25 23:50 ` [PATCH 41/71] xfs: don't allow realtime and reflinked files to mix Darrick J. Wong
2016-08-25 23:51 ` [PATCH 42/71] xfs: don't mix reflink and DAX mode for now Darrick J. Wong
2016-08-25 23:51 ` [PATCH 43/71] xfs: recognize the reflink feature bit Darrick J. Wong
2016-08-25 23:51 ` [PATCH 44/71] xfs_db: dump refcount btree data Darrick J. Wong
2016-08-25 23:51 ` [PATCH 45/71] xfs_db: add support for checking the refcount btree Darrick J. Wong
2016-08-25 23:51 ` [PATCH 46/71] xfs_db: metadump should copy the refcount btree too Darrick J. Wong
2016-08-25 23:51 ` [PATCH 47/71] xfs_db: deal with the CoW extent size hint Darrick J. Wong
2016-08-25 23:51 ` [PATCH 48/71] xfs_db: print one array element per line Darrick J. Wong
2016-08-25 23:51 ` [PATCH 49/71] xfs_growfs: report the presence of the reflink feature Darrick J. Wong
2016-08-25 23:51 ` [PATCH 50/71] xfs_io: bmap should support querying CoW fork, shared blocks Darrick J. Wong
2016-08-25 23:52 ` [PATCH 51/71] libxfs: add configure option to override system header fsxattr Darrick J. Wong
2016-08-25 23:52 ` [PATCH 52/71] xfs_io: get and set the CoW extent size hint Darrick J. Wong
2016-08-25 23:52 ` [PATCH 53/71] xfs_io: add refcount+bmap error injection types Darrick J. Wong
2016-08-25 23:52 ` [PATCH 54/71] xfs_logprint: support cowextsize reporting in log contents Darrick J. Wong
2016-08-25 23:52 ` [PATCH 55/71] xfs_logprint: support refcount redo items Darrick J. Wong
2016-08-25 23:52 ` [PATCH 56/71] xfs_logprint: support bmap " Darrick J. Wong
2016-08-25 23:52 ` [PATCH 57/71] man: document the reflink inode flag in fsxattr Darrick J. Wong
2016-08-25 23:52 ` [PATCH 58/71] man: document the inode cowextsize flags & fields Darrick J. Wong
2016-08-25 23:52 ` [PATCH 59/71] xfs_repair: fix get_agino_buf to avoid corrupting inodes Darrick J. Wong
2016-08-25 23:53 ` [PATCH 60/71] xfs_repair: check the existing refcount btree Darrick J. Wong
2016-08-25 23:53 ` [PATCH 61/71] xfs_repair: handle multiple owners of data blocks Darrick J. Wong
2016-08-25 23:53 ` [PATCH 62/71] xfs_repair: process reverse-mapping data into refcount data Darrick J. Wong
2016-08-25 23:53 ` [PATCH 63/71] xfs_repair: record reflink inode state Darrick J. Wong
2016-08-25 23:53 ` [PATCH 64/71] xfs_repair: fix inode reflink flags Darrick J. Wong
2016-08-25 23:53 ` [PATCH 65/71] xfs_repair: check the refcount btree against our observed reference counts when -n Darrick J. Wong
2016-08-25 23:53 ` [PATCH 66/71] xfs_repair: rebuild the refcount btree Darrick J. Wong
2016-08-25 23:53 ` [PATCH 67/71] xfs_repair: complain about copy-on-write leftovers Darrick J. Wong
2016-08-25 23:53 ` [PATCH 68/71] xfs_repair: check the CoW extent size hint Darrick J. Wong
2016-08-25 23:54 ` [PATCH 69/71] xfs_repair: use range query when while checking rmaps Darrick J. Wong
2016-08-25 23:54 ` [PATCH 70/71] xfs_repair: check for mergeable refcount records Darrick J. Wong
2016-08-25 23:54 ` [PATCH 71/71] mkfs.xfs: format reflink enabled filesystems Darrick J. Wong

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