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linux/fs/xfs/xfs_alloc_btree.c
Christoph Hellwig 55a7bc5a30 xfs: do not discard alloc btree blocks 
Blocks for the allocation btree are allocated from and released to
the AGFL, and thus frequently reused.  Even worse we do not have an
easy way to avoid using an AGFL block when it is discarded due to
the simple FILO list of free blocks, and thus can frequently stall
on blocks that are currently undergoing a discard.

Add a flag to the busy extent tracking structure to skip the discard
for allocation btree blocks.  In normal operation these blocks are
reused frequently enough that there is no need to discard them
anyway, but if they spill over to the allocation btree as part of a
balance we "leak" blocks that we would otherwise discard.  We could
fix this by adding another flag and keeping these block in the
rbtree even after they aren't busy any more so that we could discard
them when they migrate out of the AGFL.  Given that this would cause
significant overhead I don't think it's worthwile for now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-05-24 11:17:22 -05:00

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/*
* Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
#include "xfs_btree_trace.h"
#include "xfs_alloc.h"
#include "xfs_error.h"
#include "xfs_trace.h"
STATIC struct xfs_btree_cur *
xfs_allocbt_dup_cursor(
struct xfs_btree_cur *cur)
{
return xfs_allocbt_init_cursor(cur->bc_mp, cur->bc_tp,
cur->bc_private.a.agbp, cur->bc_private.a.agno,
cur->bc_btnum);
}
STATIC void
xfs_allocbt_set_root(
struct xfs_btree_cur *cur,
union xfs_btree_ptr *ptr,
int inc)
{
struct xfs_buf *agbp = cur->bc_private.a.agbp;
struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp);
xfs_agnumber_t seqno = be32_to_cpu(agf->agf_seqno);
int btnum = cur->bc_btnum;
struct xfs_perag *pag = xfs_perag_get(cur->bc_mp, seqno);
ASSERT(ptr->s != 0);
agf->agf_roots[btnum] = ptr->s;
be32_add_cpu(&agf->agf_levels[btnum], inc);
pag->pagf_levels[btnum] += inc;
xfs_perag_put(pag);
xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_ROOTS | XFS_AGF_LEVELS);
}
STATIC int
xfs_allocbt_alloc_block(
struct xfs_btree_cur *cur,
union xfs_btree_ptr *start,
union xfs_btree_ptr *new,
int length,
int *stat)
{
int error;
xfs_agblock_t bno;
XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
/* Allocate the new block from the freelist. If we can't, give up. */
error = xfs_alloc_get_freelist(cur->bc_tp, cur->bc_private.a.agbp,
&bno, 1);
if (error) {
XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
return error;
}
if (bno == NULLAGBLOCK) {
XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
*stat = 0;
return 0;
}
xfs_alloc_busy_reuse(cur->bc_mp, cur->bc_private.a.agno, bno, 1, false);
xfs_trans_agbtree_delta(cur->bc_tp, 1);
new->s = cpu_to_be32(bno);
XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
*stat = 1;
return 0;
}
STATIC int
xfs_allocbt_free_block(
struct xfs_btree_cur *cur,
struct xfs_buf *bp)
{
struct xfs_buf *agbp = cur->bc_private.a.agbp;
struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp);
xfs_agblock_t bno;
int error;
bno = xfs_daddr_to_agbno(cur->bc_mp, XFS_BUF_ADDR(bp));
error = xfs_alloc_put_freelist(cur->bc_tp, agbp, NULL, bno, 1);
if (error)
return error;
xfs_alloc_busy_insert(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1,
XFS_ALLOC_BUSY_SKIP_DISCARD);
xfs_trans_agbtree_delta(cur->bc_tp, -1);
return 0;
}
/*
* Update the longest extent in the AGF
*/
STATIC void
xfs_allocbt_update_lastrec(
struct xfs_btree_cur *cur,
struct xfs_btree_block *block,
union xfs_btree_rec *rec,
int ptr,
int reason)
{
struct xfs_agf *agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
xfs_agnumber_t seqno = be32_to_cpu(agf->agf_seqno);
struct xfs_perag *pag;
__be32 len;
int numrecs;
ASSERT(cur->bc_btnum == XFS_BTNUM_CNT);
switch (reason) {
case LASTREC_UPDATE:
/*
* If this is the last leaf block and it's the last record,
* then update the size of the longest extent in the AG.
*/
if (ptr != xfs_btree_get_numrecs(block))
return;
len = rec->alloc.ar_blockcount;
break;
case LASTREC_INSREC:
if (be32_to_cpu(rec->alloc.ar_blockcount) <=
be32_to_cpu(agf->agf_longest))
return;
len = rec->alloc.ar_blockcount;
break;
case LASTREC_DELREC:
numrecs = xfs_btree_get_numrecs(block);
if (ptr <= numrecs)
return;
ASSERT(ptr == numrecs + 1);
if (numrecs) {
xfs_alloc_rec_t *rrp;
rrp = XFS_ALLOC_REC_ADDR(cur->bc_mp, block, numrecs);
len = rrp->ar_blockcount;
} else {
len = 0;
}
break;
default:
ASSERT(0);
return;
}
agf->agf_longest = len;
pag = xfs_perag_get(cur->bc_mp, seqno);
pag->pagf_longest = be32_to_cpu(len);
xfs_perag_put(pag);
xfs_alloc_log_agf(cur->bc_tp, cur->bc_private.a.agbp, XFS_AGF_LONGEST);
}
STATIC int
xfs_allocbt_get_minrecs(
struct xfs_btree_cur *cur,
int level)
{
return cur->bc_mp->m_alloc_mnr[level != 0];
}
STATIC int
xfs_allocbt_get_maxrecs(
struct xfs_btree_cur *cur,
int level)
{
return cur->bc_mp->m_alloc_mxr[level != 0];
}
STATIC void
xfs_allocbt_init_key_from_rec(
union xfs_btree_key *key,
union xfs_btree_rec *rec)
{
ASSERT(rec->alloc.ar_startblock != 0);
key->alloc.ar_startblock = rec->alloc.ar_startblock;
key->alloc.ar_blockcount = rec->alloc.ar_blockcount;
}
STATIC void
xfs_allocbt_init_rec_from_key(
union xfs_btree_key *key,
union xfs_btree_rec *rec)
{
ASSERT(key->alloc.ar_startblock != 0);
rec->alloc.ar_startblock = key->alloc.ar_startblock;
rec->alloc.ar_blockcount = key->alloc.ar_blockcount;
}
STATIC void
xfs_allocbt_init_rec_from_cur(
struct xfs_btree_cur *cur,
union xfs_btree_rec *rec)
{
ASSERT(cur->bc_rec.a.ar_startblock != 0);
rec->alloc.ar_startblock = cpu_to_be32(cur->bc_rec.a.ar_startblock);
rec->alloc.ar_blockcount = cpu_to_be32(cur->bc_rec.a.ar_blockcount);
}
STATIC void
xfs_allocbt_init_ptr_from_cur(
struct xfs_btree_cur *cur,
union xfs_btree_ptr *ptr)
{
struct xfs_agf *agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
ASSERT(cur->bc_private.a.agno == be32_to_cpu(agf->agf_seqno));
ASSERT(agf->agf_roots[cur->bc_btnum] != 0);
ptr->s = agf->agf_roots[cur->bc_btnum];
}
STATIC __int64_t
xfs_allocbt_key_diff(
struct xfs_btree_cur *cur,
union xfs_btree_key *key)
{
xfs_alloc_rec_incore_t *rec = &cur->bc_rec.a;
xfs_alloc_key_t *kp = &key->alloc;
__int64_t diff;
if (cur->bc_btnum == XFS_BTNUM_BNO) {
return (__int64_t)be32_to_cpu(kp->ar_startblock) -
rec->ar_startblock;
}
diff = (__int64_t)be32_to_cpu(kp->ar_blockcount) - rec->ar_blockcount;
if (diff)
return diff;
return (__int64_t)be32_to_cpu(kp->ar_startblock) - rec->ar_startblock;
}
#ifdef DEBUG
STATIC int
xfs_allocbt_keys_inorder(
struct xfs_btree_cur *cur,
union xfs_btree_key *k1,
union xfs_btree_key *k2)
{
if (cur->bc_btnum == XFS_BTNUM_BNO) {
return be32_to_cpu(k1->alloc.ar_startblock) <
be32_to_cpu(k2->alloc.ar_startblock);
} else {
return be32_to_cpu(k1->alloc.ar_blockcount) <
be32_to_cpu(k2->alloc.ar_blockcount) ||
(k1->alloc.ar_blockcount == k2->alloc.ar_blockcount &&
be32_to_cpu(k1->alloc.ar_startblock) <
be32_to_cpu(k2->alloc.ar_startblock));
}
}
STATIC int
xfs_allocbt_recs_inorder(
struct xfs_btree_cur *cur,
union xfs_btree_rec *r1,
union xfs_btree_rec *r2)
{
if (cur->bc_btnum == XFS_BTNUM_BNO) {
return be32_to_cpu(r1->alloc.ar_startblock) +
be32_to_cpu(r1->alloc.ar_blockcount) <=
be32_to_cpu(r2->alloc.ar_startblock);
} else {
return be32_to_cpu(r1->alloc.ar_blockcount) <
be32_to_cpu(r2->alloc.ar_blockcount) ||
(r1->alloc.ar_blockcount == r2->alloc.ar_blockcount &&
be32_to_cpu(r1->alloc.ar_startblock) <
be32_to_cpu(r2->alloc.ar_startblock));
}
}
#endif /* DEBUG */
#ifdef XFS_BTREE_TRACE
ktrace_t *xfs_allocbt_trace_buf;
STATIC void
xfs_allocbt_trace_enter(
struct xfs_btree_cur *cur,
const char *func,
char *s,
int type,
int line,
__psunsigned_t a0,
__psunsigned_t a1,
__psunsigned_t a2,
__psunsigned_t a3,
__psunsigned_t a4,
__psunsigned_t a5,
__psunsigned_t a6,
__psunsigned_t a7,
__psunsigned_t a8,
__psunsigned_t a9,
__psunsigned_t a10)
{
ktrace_enter(xfs_allocbt_trace_buf, (void *)(__psint_t)type,
(void *)func, (void *)s, NULL, (void *)cur,
(void *)a0, (void *)a1, (void *)a2, (void *)a3,
(void *)a4, (void *)a5, (void *)a6, (void *)a7,
(void *)a8, (void *)a9, (void *)a10);
}
STATIC void
xfs_allocbt_trace_cursor(
struct xfs_btree_cur *cur,
__uint32_t *s0,
__uint64_t *l0,
__uint64_t *l1)
{
*s0 = cur->bc_private.a.agno;
*l0 = cur->bc_rec.a.ar_startblock;
*l1 = cur->bc_rec.a.ar_blockcount;
}
STATIC void
xfs_allocbt_trace_key(
struct xfs_btree_cur *cur,
union xfs_btree_key *key,
__uint64_t *l0,
__uint64_t *l1)
{
*l0 = be32_to_cpu(key->alloc.ar_startblock);
*l1 = be32_to_cpu(key->alloc.ar_blockcount);
}
STATIC void
xfs_allocbt_trace_record(
struct xfs_btree_cur *cur,
union xfs_btree_rec *rec,
__uint64_t *l0,
__uint64_t *l1,
__uint64_t *l2)
{
*l0 = be32_to_cpu(rec->alloc.ar_startblock);
*l1 = be32_to_cpu(rec->alloc.ar_blockcount);
*l2 = 0;
}
#endif /* XFS_BTREE_TRACE */
static const struct xfs_btree_ops xfs_allocbt_ops = {
.rec_len = sizeof(xfs_alloc_rec_t),
.key_len = sizeof(xfs_alloc_key_t),
.dup_cursor = xfs_allocbt_dup_cursor,
.set_root = xfs_allocbt_set_root,
.alloc_block = xfs_allocbt_alloc_block,
.free_block = xfs_allocbt_free_block,
.update_lastrec = xfs_allocbt_update_lastrec,
.get_minrecs = xfs_allocbt_get_minrecs,
.get_maxrecs = xfs_allocbt_get_maxrecs,
.init_key_from_rec = xfs_allocbt_init_key_from_rec,
.init_rec_from_key = xfs_allocbt_init_rec_from_key,
.init_rec_from_cur = xfs_allocbt_init_rec_from_cur,
.init_ptr_from_cur = xfs_allocbt_init_ptr_from_cur,
.key_diff = xfs_allocbt_key_diff,
#ifdef DEBUG
.keys_inorder = xfs_allocbt_keys_inorder,
.recs_inorder = xfs_allocbt_recs_inorder,
#endif
#ifdef XFS_BTREE_TRACE
.trace_enter = xfs_allocbt_trace_enter,
.trace_cursor = xfs_allocbt_trace_cursor,
.trace_key = xfs_allocbt_trace_key,
.trace_record = xfs_allocbt_trace_record,
#endif
};
/*
* Allocate a new allocation btree cursor.
*/
struct xfs_btree_cur * /* new alloc btree cursor */
xfs_allocbt_init_cursor(
struct xfs_mount *mp, /* file system mount point */
struct xfs_trans *tp, /* transaction pointer */
struct xfs_buf *agbp, /* buffer for agf structure */
xfs_agnumber_t agno, /* allocation group number */
xfs_btnum_t btnum) /* btree identifier */
{
struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp);
struct xfs_btree_cur *cur;
ASSERT(btnum == XFS_BTNUM_BNO || btnum == XFS_BTNUM_CNT);
cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_SLEEP);
cur->bc_tp = tp;
cur->bc_mp = mp;
cur->bc_nlevels = be32_to_cpu(agf->agf_levels[btnum]);
cur->bc_btnum = btnum;
cur->bc_blocklog = mp->m_sb.sb_blocklog;
cur->bc_ops = &xfs_allocbt_ops;
if (btnum == XFS_BTNUM_CNT)
cur->bc_flags = XFS_BTREE_LASTREC_UPDATE;
cur->bc_private.a.agbp = agbp;
cur->bc_private.a.agno = agno;
return cur;
}
/*
* Calculate number of records in an alloc btree block.
*/
int
xfs_allocbt_maxrecs(
struct xfs_mount *mp,
int blocklen,
int leaf)
{
blocklen -= XFS_ALLOC_BLOCK_LEN(mp);
if (leaf)
return blocklen / sizeof(xfs_alloc_rec_t);
return blocklen / (sizeof(xfs_alloc_key_t) + sizeof(xfs_alloc_ptr_t));
}
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