4be536debe
The fix for recent ENOSPC deadlocks introduced certain limitations on allocations. The fix could cause xfssyncd to loop endlessly if we did not leave some space free for the allocator to work correctly. Basically, we needed to ensure that we had at least 4 blocks free for an AG free list and a block for the inode bmap btree at all times. However, this did not take into account the fact that each AG has a free list that needs 4 blocks. Hence any filesystem with more than one AG could cause oversubscription of free space and make xfssyncd spin forever trying to allocate space needed for AG freelists that was not available in the AG. The following patch reserves space for the free lists in all AGs plus the inode bmap btree which prevents oversubscription. It also prevents those blocks from being reported as free space (as they can never be used) and makes the SMP in-core superblock accounting code and the reserved block ioctl respect this requirement. SGI-PV: 955674 SGI-Modid: xfs-linux-melb:xfs-kern:26894a Signed-off-by: David Chinner <dgc@sgi.com> Signed-off-by: David Chatterton <chatz@sgi.com>
211 lines
6.9 KiB
C
211 lines
6.9 KiB
C
/*
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* Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __XFS_ALLOC_H__
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#define __XFS_ALLOC_H__
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struct xfs_buf;
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struct xfs_mount;
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struct xfs_perag;
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struct xfs_trans;
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/*
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* Freespace allocation types. Argument to xfs_alloc_[v]extent.
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*/
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typedef enum xfs_alloctype
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{
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XFS_ALLOCTYPE_ANY_AG, /* allocate anywhere, use rotor */
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XFS_ALLOCTYPE_FIRST_AG, /* ... start at ag 0 */
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XFS_ALLOCTYPE_START_AG, /* anywhere, start in this a.g. */
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XFS_ALLOCTYPE_THIS_AG, /* anywhere in this a.g. */
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XFS_ALLOCTYPE_START_BNO, /* near this block else anywhere */
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XFS_ALLOCTYPE_NEAR_BNO, /* in this a.g. and near this block */
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XFS_ALLOCTYPE_THIS_BNO /* at exactly this block */
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} xfs_alloctype_t;
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/*
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* Flags for xfs_alloc_fix_freelist.
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*/
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#define XFS_ALLOC_FLAG_TRYLOCK 0x00000001 /* use trylock for buffer locking */
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#define XFS_ALLOC_FLAG_FREEING 0x00000002 /* indicate caller is freeing extents*/
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/*
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* In order to avoid ENOSPC-related deadlock caused by
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* out-of-order locking of AGF buffer (PV 947395), we place
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* constraints on the relationship among actual allocations for
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* data blocks, freelist blocks, and potential file data bmap
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* btree blocks. However, these restrictions may result in no
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* actual space allocated for a delayed extent, for example, a data
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* block in a certain AG is allocated but there is no additional
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* block for the additional bmap btree block due to a split of the
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* bmap btree of the file. The result of this may lead to an
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* infinite loop in xfssyncd when the file gets flushed to disk and
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* all delayed extents need to be actually allocated. To get around
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* this, we explicitly set aside a few blocks which will not be
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* reserved in delayed allocation. Considering the minimum number of
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* needed freelist blocks is 4 fsbs _per AG_, a potential split of file's bmap
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* btree requires 1 fsb, so we set the number of set-aside blocks
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* to 4 + 4*agcount.
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*/
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#define XFS_ALLOC_SET_ASIDE(mp) (4 + ((mp)->m_sb.sb_agcount * 4))
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/*
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* Argument structure for xfs_alloc routines.
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* This is turned into a structure to avoid having 20 arguments passed
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* down several levels of the stack.
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*/
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typedef struct xfs_alloc_arg {
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struct xfs_trans *tp; /* transaction pointer */
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struct xfs_mount *mp; /* file system mount point */
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struct xfs_buf *agbp; /* buffer for a.g. freelist header */
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struct xfs_perag *pag; /* per-ag struct for this agno */
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xfs_fsblock_t fsbno; /* file system block number */
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xfs_agnumber_t agno; /* allocation group number */
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xfs_agblock_t agbno; /* allocation group-relative block # */
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xfs_extlen_t minlen; /* minimum size of extent */
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xfs_extlen_t maxlen; /* maximum size of extent */
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xfs_extlen_t mod; /* mod value for extent size */
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xfs_extlen_t prod; /* prod value for extent size */
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xfs_extlen_t minleft; /* min blocks must be left after us */
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xfs_extlen_t total; /* total blocks needed in xaction */
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xfs_extlen_t alignment; /* align answer to multiple of this */
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xfs_extlen_t minalignslop; /* slop for minlen+alignment calcs */
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xfs_extlen_t len; /* output: actual size of extent */
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xfs_alloctype_t type; /* allocation type XFS_ALLOCTYPE_... */
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xfs_alloctype_t otype; /* original allocation type */
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char wasdel; /* set if allocation was prev delayed */
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char wasfromfl; /* set if allocation is from freelist */
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char isfl; /* set if is freelist blocks - !acctg */
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char userdata; /* set if this is user data */
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xfs_fsblock_t firstblock; /* io first block allocated */
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} xfs_alloc_arg_t;
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/*
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* Defines for userdata
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*/
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#define XFS_ALLOC_USERDATA 1 /* allocation is for user data*/
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#define XFS_ALLOC_INITIAL_USER_DATA 2 /* special case start of file */
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#ifdef __KERNEL__
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#if defined(XFS_ALLOC_TRACE)
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/*
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* Allocation tracing buffer size.
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*/
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#define XFS_ALLOC_TRACE_SIZE 4096
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extern ktrace_t *xfs_alloc_trace_buf;
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/*
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* Types for alloc tracing.
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*/
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#define XFS_ALLOC_KTRACE_ALLOC 1
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#define XFS_ALLOC_KTRACE_FREE 2
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#define XFS_ALLOC_KTRACE_MODAGF 3
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#define XFS_ALLOC_KTRACE_BUSY 4
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#define XFS_ALLOC_KTRACE_UNBUSY 5
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#define XFS_ALLOC_KTRACE_BUSYSEARCH 6
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#endif
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/*
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* Compute and fill in value of m_ag_maxlevels.
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*/
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void
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xfs_alloc_compute_maxlevels(
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struct xfs_mount *mp); /* file system mount structure */
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/*
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* Get a block from the freelist.
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* Returns with the buffer for the block gotten.
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*/
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int /* error */
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xfs_alloc_get_freelist(
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struct xfs_trans *tp, /* transaction pointer */
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struct xfs_buf *agbp, /* buffer containing the agf structure */
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xfs_agblock_t *bnop); /* block address retrieved from freelist */
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/*
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* Log the given fields from the agf structure.
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*/
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void
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xfs_alloc_log_agf(
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struct xfs_trans *tp, /* transaction pointer */
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struct xfs_buf *bp, /* buffer for a.g. freelist header */
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int fields);/* mask of fields to be logged (XFS_AGF_...) */
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/*
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* Interface for inode allocation to force the pag data to be initialized.
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*/
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int /* error */
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xfs_alloc_pagf_init(
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struct xfs_mount *mp, /* file system mount structure */
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struct xfs_trans *tp, /* transaction pointer */
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xfs_agnumber_t agno, /* allocation group number */
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int flags); /* XFS_ALLOC_FLAGS_... */
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/*
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* Put the block on the freelist for the allocation group.
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*/
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int /* error */
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xfs_alloc_put_freelist(
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struct xfs_trans *tp, /* transaction pointer */
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struct xfs_buf *agbp, /* buffer for a.g. freelist header */
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struct xfs_buf *agflbp,/* buffer for a.g. free block array */
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xfs_agblock_t bno); /* block being freed */
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/*
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* Read in the allocation group header (free/alloc section).
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*/
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int /* error */
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xfs_alloc_read_agf(
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struct xfs_mount *mp, /* mount point structure */
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struct xfs_trans *tp, /* transaction pointer */
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xfs_agnumber_t agno, /* allocation group number */
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int flags, /* XFS_ALLOC_FLAG_... */
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struct xfs_buf **bpp); /* buffer for the ag freelist header */
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/*
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* Allocate an extent (variable-size).
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*/
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int /* error */
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xfs_alloc_vextent(
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xfs_alloc_arg_t *args); /* allocation argument structure */
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/*
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* Free an extent.
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*/
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int /* error */
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xfs_free_extent(
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struct xfs_trans *tp, /* transaction pointer */
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xfs_fsblock_t bno, /* starting block number of extent */
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xfs_extlen_t len); /* length of extent */
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void
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xfs_alloc_mark_busy(xfs_trans_t *tp,
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xfs_agnumber_t agno,
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xfs_agblock_t bno,
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xfs_extlen_t len);
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void
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xfs_alloc_clear_busy(xfs_trans_t *tp,
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xfs_agnumber_t ag,
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int idx);
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#endif /* __KERNEL__ */
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#endif /* __XFS_ALLOC_H__ */
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