80 lines
3.0 KiB
Diff
80 lines
3.0 KiB
Diff
From de7d5664d0f7a4a29c32aa98331d965f6c5c6de8 Mon Sep 17 00:00:00 2001
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From: Brian Foster <bfoster@redhat.com>
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Date: Tue, 15 Sep 2020 15:59:38 -0400
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Subject: [PATCH 11/16] xfs: fix off-by-one in inode alloc block reservation
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calculation
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Source kernel commit: 657f101930bc6c5b41bd7d6c22565c4302a80d33
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The inode chunk allocation transaction reserves inobt_maxlevels-1
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blocks to accommodate a full split of the inode btree. A full split
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requires an allocation for every existing level and a new root
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block, which means inobt_maxlevels is the worst case block
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requirement for a transaction that inserts to the inobt. This can
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lead to a transaction block reservation overrun when tmpfile
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creation allocates an inode chunk and expands the inobt to its
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maximum depth. This problem has been observed in conjunction with
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overlayfs, which makes frequent use of tmpfiles internally.
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The existing reservation code goes back as far as the Linux git repo
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history (v2.6.12). It was likely never observed as a problem because
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the traditional file/directory creation transactions also include
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worst case block reservation for directory modifications, which most
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likely is able to make up for a single block deficiency in the inode
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allocation portion of the calculation. tmpfile support is relatively
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more recent (v3.15), less heavily used, and only includes the inode
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allocation block reservation as tmpfiles aren't linked into the
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directory tree on creation.
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Fix up the inode alloc block reservation macro and a couple of the
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block allocator minleft parameters that enforce an allocation to
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leave enough free blocks in the AG for a full inobt split.
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Signed-off-by: Brian Foster <bfoster@redhat.com>
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Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
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Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
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---
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libxfs/xfs_ialloc.c | 4 ++--
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libxfs/xfs_trans_space.h | 2 +-
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2 files changed, 3 insertions(+), 3 deletions(-)
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diff --git a/libxfs/xfs_ialloc.c b/libxfs/xfs_ialloc.c
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index 00b3326..750b223 100644
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--- a/libxfs/xfs_ialloc.c
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+++ b/libxfs/xfs_ialloc.c
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@@ -683,7 +683,7 @@ xfs_ialloc_ag_alloc(
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args.minalignslop = igeo->cluster_align - 1;
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/* Allow space for the inode btree to split. */
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- args.minleft = igeo->inobt_maxlevels - 1;
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+ args.minleft = igeo->inobt_maxlevels;
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if ((error = xfs_alloc_vextent(&args)))
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return error;
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@@ -731,7 +731,7 @@ xfs_ialloc_ag_alloc(
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/*
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* Allow space for the inode btree to split.
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*/
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- args.minleft = igeo->inobt_maxlevels - 1;
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+ args.minleft = igeo->inobt_maxlevels;
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if ((error = xfs_alloc_vextent(&args)))
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return error;
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}
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diff --git a/libxfs/xfs_trans_space.h b/libxfs/xfs_trans_space.h
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index c6df01a..7ad3659 100644
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--- a/libxfs/xfs_trans_space.h
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+++ b/libxfs/xfs_trans_space.h
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@@ -58,7 +58,7 @@
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#define XFS_IALLOC_SPACE_RES(mp) \
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(M_IGEO(mp)->ialloc_blks + \
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((xfs_sb_version_hasfinobt(&mp->m_sb) ? 2 : 1) * \
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- (M_IGEO(mp)->inobt_maxlevels - 1)))
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+ M_IGEO(mp)->inobt_maxlevels))
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/*
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* Space reservation values for various transactions.
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--
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1.8.3.1
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