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linux-next/fs/xfs/libxfs/xfs_rmap_btree.c
Dave Chinner 11ef38afe9 xfs: make xfs btree stats less huge 
Embedding a switch statement in every btree stats inc/add adds a lot
of code overhead to the core btree infrastructure paths. Stats are
supposed to be small and lightweight, but the btree stats have
become big and bloated as we've added more btrees. It needs fixing
because the reflink code will just add more overhead again.

Convert the v2 btree stats to arrays instead of independent
variables, and instead use the type to index the specific btree
array via an enum. This allows us to use array based indexing
to update the stats, rather than having to derefence variables
specific to the btree type.

If we then wrap the xfsstats structure in a union and place uint32_t
array beside it, and calculate the correct btree stats array base
array index when creating a btree cursor,  we can easily access
entries in the stats structure without having to switch names based
on the btree type.

We then replace with the switch statement with a simple set of stats
wrapper macros, resulting in a significant simplification of the
btree stats code, and:

   text	   data	    bss	    dec	    hex	filename
  48905	    144	      8	  49057	   bfa1	fs/xfs/libxfs/xfs_btree.o.old
  36793	    144	      8	  36945	   9051	fs/xfs/libxfs/xfs_btree.o

it reduces the core btree infrastructure code size by close to 25%!

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-12-05 14:38:58 +11:00

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/*
* Copyright (c) 2014 Red Hat, 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_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_alloc.h"
#include "xfs_btree.h"
#include "xfs_rmap.h"
#include "xfs_rmap_btree.h"
#include "xfs_trace.h"
#include "xfs_cksum.h"
#include "xfs_error.h"
#include "xfs_extent_busy.h"
#include "xfs_ag_resv.h"
/*
* Reverse map btree.
*
* This is a per-ag tree used to track the owner(s) of a given extent. With
* reflink it is possible for there to be multiple owners, which is a departure
* from classic XFS. Owner records for data extents are inserted when the
* extent is mapped and removed when an extent is unmapped. Owner records for
* all other block types (i.e. metadata) are inserted when an extent is
* allocated and removed when an extent is freed. There can only be one owner
* of a metadata extent, usually an inode or some other metadata structure like
* an AG btree.
*
* The rmap btree is part of the free space management, so blocks for the tree
* are sourced from the agfl. Hence we need transaction reservation support for
* this tree so that the freelist is always large enough. This also impacts on
* the minimum space we need to leave free in the AG.
*
* The tree is ordered by [ag block, owner, offset]. This is a large key size,
* but it is the only way to enforce unique keys when a block can be owned by
* multiple files at any offset. There's no need to order/search by extent
* size for online updating/management of the tree. It is intended that most
* reverse lookups will be to find the owner(s) of a particular block, or to
* try to recover tree and file data from corrupt primary metadata.
*/
static struct xfs_btree_cur *
xfs_rmapbt_dup_cursor(
struct xfs_btree_cur *cur)
{
return xfs_rmapbt_init_cursor(cur->bc_mp, cur->bc_tp,
cur->bc_private.a.agbp, cur->bc_private.a.agno);
}
STATIC void
xfs_rmapbt_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_rmapbt_alloc_block(
struct xfs_btree_cur *cur,
union xfs_btree_ptr *start,
union xfs_btree_ptr *new,
int *stat)
{
struct xfs_buf *agbp = cur->bc_private.a.agbp;
struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp);
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;
}
trace_xfs_rmapbt_alloc_block(cur->bc_mp, cur->bc_private.a.agno,
bno, 1);
if (bno == NULLAGBLOCK) {
XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
*stat = 0;
return 0;
}
xfs_extent_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);
be32_add_cpu(&agf->agf_rmap_blocks, 1);
xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
*stat = 1;
return 0;
}
STATIC int
xfs_rmapbt_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));
trace_xfs_rmapbt_free_block(cur->bc_mp, cur->bc_private.a.agno,
bno, 1);
be32_add_cpu(&agf->agf_rmap_blocks, -1);
xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
error = xfs_alloc_put_freelist(cur->bc_tp, agbp, NULL, bno, 1);
if (error)
return error;
xfs_extent_busy_insert(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1,
XFS_EXTENT_BUSY_SKIP_DISCARD);
xfs_trans_agbtree_delta(cur->bc_tp, -1);
return 0;
}
STATIC int
xfs_rmapbt_get_minrecs(
struct xfs_btree_cur *cur,
int level)
{
return cur->bc_mp->m_rmap_mnr[level != 0];
}
STATIC int
xfs_rmapbt_get_maxrecs(
struct xfs_btree_cur *cur,
int level)
{
return cur->bc_mp->m_rmap_mxr[level != 0];
}
STATIC void
xfs_rmapbt_init_key_from_rec(
union xfs_btree_key *key,
union xfs_btree_rec *rec)
{
key->rmap.rm_startblock = rec->rmap.rm_startblock;
key->rmap.rm_owner = rec->rmap.rm_owner;
key->rmap.rm_offset = rec->rmap.rm_offset;
}
/*
* The high key for a reverse mapping record can be computed by shifting
* the startblock and offset to the highest value that would still map
* to that record. In practice this means that we add blockcount-1 to
* the startblock for all records, and if the record is for a data/attr
* fork mapping, we add blockcount-1 to the offset too.
*/
STATIC void
xfs_rmapbt_init_high_key_from_rec(
union xfs_btree_key *key,
union xfs_btree_rec *rec)
{
__uint64_t off;
int adj;
adj = be32_to_cpu(rec->rmap.rm_blockcount) - 1;
key->rmap.rm_startblock = rec->rmap.rm_startblock;
be32_add_cpu(&key->rmap.rm_startblock, adj);
key->rmap.rm_owner = rec->rmap.rm_owner;
key->rmap.rm_offset = rec->rmap.rm_offset;
if (XFS_RMAP_NON_INODE_OWNER(be64_to_cpu(rec->rmap.rm_owner)) ||
XFS_RMAP_IS_BMBT_BLOCK(be64_to_cpu(rec->rmap.rm_offset)))
return;
off = be64_to_cpu(key->rmap.rm_offset);
off = (XFS_RMAP_OFF(off) + adj) | (off & ~XFS_RMAP_OFF_MASK);
key->rmap.rm_offset = cpu_to_be64(off);
}
STATIC void
xfs_rmapbt_init_rec_from_cur(
struct xfs_btree_cur *cur,
union xfs_btree_rec *rec)
{
rec->rmap.rm_startblock = cpu_to_be32(cur->bc_rec.r.rm_startblock);
rec->rmap.rm_blockcount = cpu_to_be32(cur->bc_rec.r.rm_blockcount);
rec->rmap.rm_owner = cpu_to_be64(cur->bc_rec.r.rm_owner);
rec->rmap.rm_offset = cpu_to_be64(
xfs_rmap_irec_offset_pack(&cur->bc_rec.r));
}
STATIC void
xfs_rmapbt_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_rmapbt_key_diff(
struct xfs_btree_cur *cur,
union xfs_btree_key *key)
{
struct xfs_rmap_irec *rec = &cur->bc_rec.r;
struct xfs_rmap_key *kp = &key->rmap;
__u64 x, y;
__int64_t d;
d = (__int64_t)be32_to_cpu(kp->rm_startblock) - rec->rm_startblock;
if (d)
return d;
x = be64_to_cpu(kp->rm_owner);
y = rec->rm_owner;
if (x > y)
return 1;
else if (y > x)
return -1;
x = XFS_RMAP_OFF(be64_to_cpu(kp->rm_offset));
y = rec->rm_offset;
if (x > y)
return 1;
else if (y > x)
return -1;
return 0;
}
STATIC __int64_t
xfs_rmapbt_diff_two_keys(
struct xfs_btree_cur *cur,
union xfs_btree_key *k1,
union xfs_btree_key *k2)
{
struct xfs_rmap_key *kp1 = &k1->rmap;
struct xfs_rmap_key *kp2 = &k2->rmap;
__int64_t d;
__u64 x, y;
d = (__int64_t)be32_to_cpu(kp1->rm_startblock) -
be32_to_cpu(kp2->rm_startblock);
if (d)
return d;
x = be64_to_cpu(kp1->rm_owner);
y = be64_to_cpu(kp2->rm_owner);
if (x > y)
return 1;
else if (y > x)
return -1;
x = XFS_RMAP_OFF(be64_to_cpu(kp1->rm_offset));
y = XFS_RMAP_OFF(be64_to_cpu(kp2->rm_offset));
if (x > y)
return 1;
else if (y > x)
return -1;
return 0;
}
static bool
xfs_rmapbt_verify(
struct xfs_buf *bp)
{
struct xfs_mount *mp = bp->b_target->bt_mount;
struct xfs_btree_block *block = XFS_BUF_TO_BLOCK(bp);
struct xfs_perag *pag = bp->b_pag;
unsigned int level;
/*
* magic number and level verification
*
* During growfs operations, we can't verify the exact level or owner as
* the perag is not fully initialised and hence not attached to the
* buffer. In this case, check against the maximum tree depth.
*
* Similarly, during log recovery we will have a perag structure
* attached, but the agf information will not yet have been initialised
* from the on disk AGF. Again, we can only check against maximum limits
* in this case.
*/
if (block->bb_magic != cpu_to_be32(XFS_RMAP_CRC_MAGIC))
return false;
if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
return false;
if (!xfs_btree_sblock_v5hdr_verify(bp))
return false;
level = be16_to_cpu(block->bb_level);
if (pag && pag->pagf_init) {
if (level >= pag->pagf_levels[XFS_BTNUM_RMAPi])
return false;
} else if (level >= mp->m_rmap_maxlevels)
return false;
return xfs_btree_sblock_verify(bp, mp->m_rmap_mxr[level != 0]);
}
static void
xfs_rmapbt_read_verify(
struct xfs_buf *bp)
{
if (!xfs_btree_sblock_verify_crc(bp))
xfs_buf_ioerror(bp, -EFSBADCRC);
else if (!xfs_rmapbt_verify(bp))
xfs_buf_ioerror(bp, -EFSCORRUPTED);
if (bp->b_error) {
trace_xfs_btree_corrupt(bp, _RET_IP_);
xfs_verifier_error(bp);
}
}
static void
xfs_rmapbt_write_verify(
struct xfs_buf *bp)
{
if (!xfs_rmapbt_verify(bp)) {
trace_xfs_btree_corrupt(bp, _RET_IP_);
xfs_buf_ioerror(bp, -EFSCORRUPTED);
xfs_verifier_error(bp);
return;
}
xfs_btree_sblock_calc_crc(bp);
}
const struct xfs_buf_ops xfs_rmapbt_buf_ops = {
.name = "xfs_rmapbt",
.verify_read = xfs_rmapbt_read_verify,
.verify_write = xfs_rmapbt_write_verify,
};
#if defined(DEBUG) || defined(XFS_WARN)
STATIC int
xfs_rmapbt_keys_inorder(
struct xfs_btree_cur *cur,
union xfs_btree_key *k1,
union xfs_btree_key *k2)
{
__uint32_t x;
__uint32_t y;
__uint64_t a;
__uint64_t b;
x = be32_to_cpu(k1->rmap.rm_startblock);
y = be32_to_cpu(k2->rmap.rm_startblock);
if (x < y)
return 1;
else if (x > y)
return 0;
a = be64_to_cpu(k1->rmap.rm_owner);
b = be64_to_cpu(k2->rmap.rm_owner);
if (a < b)
return 1;
else if (a > b)
return 0;
a = XFS_RMAP_OFF(be64_to_cpu(k1->rmap.rm_offset));
b = XFS_RMAP_OFF(be64_to_cpu(k2->rmap.rm_offset));
if (a <= b)
return 1;
return 0;
}
STATIC int
xfs_rmapbt_recs_inorder(
struct xfs_btree_cur *cur,
union xfs_btree_rec *r1,
union xfs_btree_rec *r2)
{
__uint32_t x;
__uint32_t y;
__uint64_t a;
__uint64_t b;
x = be32_to_cpu(r1->rmap.rm_startblock);
y = be32_to_cpu(r2->rmap.rm_startblock);
if (x < y)
return 1;
else if (x > y)
return 0;
a = be64_to_cpu(r1->rmap.rm_owner);
b = be64_to_cpu(r2->rmap.rm_owner);
if (a < b)
return 1;
else if (a > b)
return 0;
a = XFS_RMAP_OFF(be64_to_cpu(r1->rmap.rm_offset));
b = XFS_RMAP_OFF(be64_to_cpu(r2->rmap.rm_offset));
if (a <= b)
return 1;
return 0;
}
#endif /* DEBUG */
static const struct xfs_btree_ops xfs_rmapbt_ops = {
.rec_len = sizeof(struct xfs_rmap_rec),
.key_len = 2 * sizeof(struct xfs_rmap_key),
.dup_cursor = xfs_rmapbt_dup_cursor,
.set_root = xfs_rmapbt_set_root,
.alloc_block = xfs_rmapbt_alloc_block,
.free_block = xfs_rmapbt_free_block,
.get_minrecs = xfs_rmapbt_get_minrecs,
.get_maxrecs = xfs_rmapbt_get_maxrecs,
.init_key_from_rec = xfs_rmapbt_init_key_from_rec,
.init_high_key_from_rec = xfs_rmapbt_init_high_key_from_rec,
.init_rec_from_cur = xfs_rmapbt_init_rec_from_cur,
.init_ptr_from_cur = xfs_rmapbt_init_ptr_from_cur,
.key_diff = xfs_rmapbt_key_diff,
.buf_ops = &xfs_rmapbt_buf_ops,
.diff_two_keys = xfs_rmapbt_diff_two_keys,
#if defined(DEBUG) || defined(XFS_WARN)
.keys_inorder = xfs_rmapbt_keys_inorder,
.recs_inorder = xfs_rmapbt_recs_inorder,
#endif
};
/*
* Allocate a new allocation btree cursor.
*/
struct xfs_btree_cur *
xfs_rmapbt_init_cursor(
struct xfs_mount *mp,
struct xfs_trans *tp,
struct xfs_buf *agbp,
xfs_agnumber_t agno)
{
struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp);
struct xfs_btree_cur *cur;
cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_NOFS);
cur->bc_tp = tp;
cur->bc_mp = mp;
/* Overlapping btree; 2 keys per pointer. */
cur->bc_btnum = XFS_BTNUM_RMAP;
cur->bc_flags = XFS_BTREE_CRC_BLOCKS | XFS_BTREE_OVERLAPPING;
cur->bc_blocklog = mp->m_sb.sb_blocklog;
cur->bc_ops = &xfs_rmapbt_ops;
cur->bc_nlevels = be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]);
cur->bc_statoff = XFS_STATS_CALC_INDEX(xs_rmap_2);
cur->bc_private.a.agbp = agbp;
cur->bc_private.a.agno = agno;
return cur;
}
/*
* Calculate number of records in an rmap btree block.
*/
int
xfs_rmapbt_maxrecs(
struct xfs_mount *mp,
int blocklen,
int leaf)
{
blocklen -= XFS_RMAP_BLOCK_LEN;
if (leaf)
return blocklen / sizeof(struct xfs_rmap_rec);
return blocklen /
(2 * sizeof(struct xfs_rmap_key) + sizeof(xfs_rmap_ptr_t));
}
/* Compute the maximum height of an rmap btree. */
void
xfs_rmapbt_compute_maxlevels(
struct xfs_mount *mp)
{
/*
* On a non-reflink filesystem, the maximum number of rmap
* records is the number of blocks in the AG, hence the max
* rmapbt height is log_$maxrecs($agblocks). However, with
* reflink each AG block can have up to 2^32 (per the refcount
* record format) owners, which means that theoretically we
* could face up to 2^64 rmap records.
*
* That effectively means that the max rmapbt height must be
* XFS_BTREE_MAXLEVELS. "Fortunately" we'll run out of AG
* blocks to feed the rmapbt long before the rmapbt reaches
* maximum height. The reflink code uses ag_resv_critical to
* disallow reflinking when less than 10% of the per-AG metadata
* block reservation since the fallback is a regular file copy.
*/
if (xfs_sb_version_hasreflink(&mp->m_sb))
mp->m_rmap_maxlevels = XFS_BTREE_MAXLEVELS;
else
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;
}
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