linux/fs/xfs/xfs_fsops.c
David Chinner 4be536debe [XFS] Prevent free space oversubscription and xfssyncd looping.
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>
2006-09-07 14:26:50 +10:00

600 lines
16 KiB
C

/*
* Copyright (c) 2000-2005 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_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_btree.h"
#include "xfs_error.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_fsops.h"
#include "xfs_itable.h"
#include "xfs_trans_space.h"
#include "xfs_rtalloc.h"
#include "xfs_rw.h"
/*
* File system operations
*/
int
xfs_fs_geometry(
xfs_mount_t *mp,
xfs_fsop_geom_t *geo,
int new_version)
{
geo->blocksize = mp->m_sb.sb_blocksize;
geo->rtextsize = mp->m_sb.sb_rextsize;
geo->agblocks = mp->m_sb.sb_agblocks;
geo->agcount = mp->m_sb.sb_agcount;
geo->logblocks = mp->m_sb.sb_logblocks;
geo->sectsize = mp->m_sb.sb_sectsize;
geo->inodesize = mp->m_sb.sb_inodesize;
geo->imaxpct = mp->m_sb.sb_imax_pct;
geo->datablocks = mp->m_sb.sb_dblocks;
geo->rtblocks = mp->m_sb.sb_rblocks;
geo->rtextents = mp->m_sb.sb_rextents;
geo->logstart = mp->m_sb.sb_logstart;
ASSERT(sizeof(geo->uuid)==sizeof(mp->m_sb.sb_uuid));
memcpy(geo->uuid, &mp->m_sb.sb_uuid, sizeof(mp->m_sb.sb_uuid));
if (new_version >= 2) {
geo->sunit = mp->m_sb.sb_unit;
geo->swidth = mp->m_sb.sb_width;
}
if (new_version >= 3) {
geo->version = XFS_FSOP_GEOM_VERSION;
geo->flags =
(XFS_SB_VERSION_HASATTR(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_ATTR : 0) |
(XFS_SB_VERSION_HASNLINK(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_NLINK : 0) |
(XFS_SB_VERSION_HASQUOTA(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_QUOTA : 0) |
(XFS_SB_VERSION_HASALIGN(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_IALIGN : 0) |
(XFS_SB_VERSION_HASDALIGN(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_DALIGN : 0) |
(XFS_SB_VERSION_HASSHARED(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_SHARED : 0) |
(XFS_SB_VERSION_HASEXTFLGBIT(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_EXTFLG : 0) |
(XFS_SB_VERSION_HASDIRV2(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_DIRV2 : 0) |
(XFS_SB_VERSION_HASSECTOR(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_SECTOR : 0) |
(XFS_SB_VERSION_HASATTR2(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_ATTR2 : 0);
geo->logsectsize = XFS_SB_VERSION_HASSECTOR(&mp->m_sb) ?
mp->m_sb.sb_logsectsize : BBSIZE;
geo->rtsectsize = mp->m_sb.sb_blocksize;
geo->dirblocksize = mp->m_dirblksize;
}
if (new_version >= 4) {
geo->flags |=
(XFS_SB_VERSION_HASLOGV2(&mp->m_sb) ?
XFS_FSOP_GEOM_FLAGS_LOGV2 : 0);
geo->logsunit = mp->m_sb.sb_logsunit;
}
return 0;
}
static int
xfs_growfs_data_private(
xfs_mount_t *mp, /* mount point for filesystem */
xfs_growfs_data_t *in) /* growfs data input struct */
{
xfs_agf_t *agf;
xfs_agi_t *agi;
xfs_agnumber_t agno;
xfs_extlen_t agsize;
xfs_extlen_t tmpsize;
xfs_alloc_rec_t *arec;
xfs_btree_sblock_t *block;
xfs_buf_t *bp;
int bucket;
int dpct;
int error;
xfs_agnumber_t nagcount;
xfs_agnumber_t nagimax = 0;
xfs_rfsblock_t nb, nb_mod;
xfs_rfsblock_t new;
xfs_rfsblock_t nfree;
xfs_agnumber_t oagcount;
int pct;
xfs_sb_t *sbp;
xfs_trans_t *tp;
nb = in->newblocks;
pct = in->imaxpct;
if (nb < mp->m_sb.sb_dblocks || pct < 0 || pct > 100)
return XFS_ERROR(EINVAL);
dpct = pct - mp->m_sb.sb_imax_pct;
error = xfs_read_buf(mp, mp->m_ddev_targp,
XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
XFS_FSS_TO_BB(mp, 1), 0, &bp);
if (error)
return error;
ASSERT(bp);
xfs_buf_relse(bp);
new = nb; /* use new as a temporary here */
nb_mod = do_div(new, mp->m_sb.sb_agblocks);
nagcount = new + (nb_mod != 0);
if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
nagcount--;
nb = nagcount * mp->m_sb.sb_agblocks;
if (nb < mp->m_sb.sb_dblocks)
return XFS_ERROR(EINVAL);
}
new = nb - mp->m_sb.sb_dblocks;
oagcount = mp->m_sb.sb_agcount;
if (nagcount > oagcount) {
down_write(&mp->m_peraglock);
mp->m_perag = kmem_realloc(mp->m_perag,
sizeof(xfs_perag_t) * nagcount,
sizeof(xfs_perag_t) * oagcount,
KM_SLEEP);
memset(&mp->m_perag[oagcount], 0,
(nagcount - oagcount) * sizeof(xfs_perag_t));
mp->m_flags |= XFS_MOUNT_32BITINODES;
nagimax = xfs_initialize_perag(XFS_MTOVFS(mp), mp, nagcount);
up_write(&mp->m_peraglock);
}
tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFS);
if ((error = xfs_trans_reserve(tp, XFS_GROWFS_SPACE_RES(mp),
XFS_GROWDATA_LOG_RES(mp), 0, 0, 0))) {
xfs_trans_cancel(tp, 0);
return error;
}
nfree = 0;
for (agno = nagcount - 1; agno >= oagcount; agno--, new -= agsize) {
/*
* AG freelist header block
*/
bp = xfs_buf_get(mp->m_ddev_targp,
XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
XFS_FSS_TO_BB(mp, 1), 0);
agf = XFS_BUF_TO_AGF(bp);
memset(agf, 0, mp->m_sb.sb_sectsize);
agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
agf->agf_seqno = cpu_to_be32(agno);
if (agno == nagcount - 1)
agsize =
nb -
(agno * (xfs_rfsblock_t)mp->m_sb.sb_agblocks);
else
agsize = mp->m_sb.sb_agblocks;
agf->agf_length = cpu_to_be32(agsize);
agf->agf_roots[XFS_BTNUM_BNOi] = cpu_to_be32(XFS_BNO_BLOCK(mp));
agf->agf_roots[XFS_BTNUM_CNTi] = cpu_to_be32(XFS_CNT_BLOCK(mp));
agf->agf_levels[XFS_BTNUM_BNOi] = cpu_to_be32(1);
agf->agf_levels[XFS_BTNUM_CNTi] = cpu_to_be32(1);
agf->agf_flfirst = 0;
agf->agf_fllast = cpu_to_be32(XFS_AGFL_SIZE(mp) - 1);
agf->agf_flcount = 0;
tmpsize = agsize - XFS_PREALLOC_BLOCKS(mp);
agf->agf_freeblks = cpu_to_be32(tmpsize);
agf->agf_longest = cpu_to_be32(tmpsize);
error = xfs_bwrite(mp, bp);
if (error) {
goto error0;
}
/*
* AG inode header block
*/
bp = xfs_buf_get(mp->m_ddev_targp,
XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
XFS_FSS_TO_BB(mp, 1), 0);
agi = XFS_BUF_TO_AGI(bp);
memset(agi, 0, mp->m_sb.sb_sectsize);
agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
agi->agi_seqno = cpu_to_be32(agno);
agi->agi_length = cpu_to_be32(agsize);
agi->agi_count = 0;
agi->agi_root = cpu_to_be32(XFS_IBT_BLOCK(mp));
agi->agi_level = cpu_to_be32(1);
agi->agi_freecount = 0;
agi->agi_newino = cpu_to_be32(NULLAGINO);
agi->agi_dirino = cpu_to_be32(NULLAGINO);
for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
error = xfs_bwrite(mp, bp);
if (error) {
goto error0;
}
/*
* BNO btree root block
*/
bp = xfs_buf_get(mp->m_ddev_targp,
XFS_AGB_TO_DADDR(mp, agno, XFS_BNO_BLOCK(mp)),
BTOBB(mp->m_sb.sb_blocksize), 0);
block = XFS_BUF_TO_SBLOCK(bp);
memset(block, 0, mp->m_sb.sb_blocksize);
block->bb_magic = cpu_to_be32(XFS_ABTB_MAGIC);
block->bb_level = 0;
block->bb_numrecs = cpu_to_be16(1);
block->bb_leftsib = cpu_to_be32(NULLAGBLOCK);
block->bb_rightsib = cpu_to_be32(NULLAGBLOCK);
arec = XFS_BTREE_REC_ADDR(mp->m_sb.sb_blocksize, xfs_alloc,
block, 1, mp->m_alloc_mxr[0]);
arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
arec->ar_blockcount = cpu_to_be32(
agsize - be32_to_cpu(arec->ar_startblock));
error = xfs_bwrite(mp, bp);
if (error) {
goto error0;
}
/*
* CNT btree root block
*/
bp = xfs_buf_get(mp->m_ddev_targp,
XFS_AGB_TO_DADDR(mp, agno, XFS_CNT_BLOCK(mp)),
BTOBB(mp->m_sb.sb_blocksize), 0);
block = XFS_BUF_TO_SBLOCK(bp);
memset(block, 0, mp->m_sb.sb_blocksize);
block->bb_magic = cpu_to_be32(XFS_ABTC_MAGIC);
block->bb_level = 0;
block->bb_numrecs = cpu_to_be16(1);
block->bb_leftsib = cpu_to_be32(NULLAGBLOCK);
block->bb_rightsib = cpu_to_be32(NULLAGBLOCK);
arec = XFS_BTREE_REC_ADDR(mp->m_sb.sb_blocksize, xfs_alloc,
block, 1, mp->m_alloc_mxr[0]);
arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
arec->ar_blockcount = cpu_to_be32(
agsize - be32_to_cpu(arec->ar_startblock));
nfree += be32_to_cpu(arec->ar_blockcount);
error = xfs_bwrite(mp, bp);
if (error) {
goto error0;
}
/*
* INO btree root block
*/
bp = xfs_buf_get(mp->m_ddev_targp,
XFS_AGB_TO_DADDR(mp, agno, XFS_IBT_BLOCK(mp)),
BTOBB(mp->m_sb.sb_blocksize), 0);
block = XFS_BUF_TO_SBLOCK(bp);
memset(block, 0, mp->m_sb.sb_blocksize);
block->bb_magic = cpu_to_be32(XFS_IBT_MAGIC);
block->bb_level = 0;
block->bb_numrecs = 0;
block->bb_leftsib = cpu_to_be32(NULLAGBLOCK);
block->bb_rightsib = cpu_to_be32(NULLAGBLOCK);
error = xfs_bwrite(mp, bp);
if (error) {
goto error0;
}
}
xfs_trans_agblocks_delta(tp, nfree);
/*
* There are new blocks in the old last a.g.
*/
if (new) {
/*
* Change the agi length.
*/
error = xfs_ialloc_read_agi(mp, tp, agno, &bp);
if (error) {
goto error0;
}
ASSERT(bp);
agi = XFS_BUF_TO_AGI(bp);
be32_add(&agi->agi_length, new);
ASSERT(nagcount == oagcount ||
be32_to_cpu(agi->agi_length) == mp->m_sb.sb_agblocks);
xfs_ialloc_log_agi(tp, bp, XFS_AGI_LENGTH);
/*
* Change agf length.
*/
error = xfs_alloc_read_agf(mp, tp, agno, 0, &bp);
if (error) {
goto error0;
}
ASSERT(bp);
agf = XFS_BUF_TO_AGF(bp);
be32_add(&agf->agf_length, new);
ASSERT(be32_to_cpu(agf->agf_length) ==
be32_to_cpu(agi->agi_length));
/*
* Free the new space.
*/
error = xfs_free_extent(tp, XFS_AGB_TO_FSB(mp, agno,
be32_to_cpu(agf->agf_length) - new), new);
if (error) {
goto error0;
}
}
if (nagcount > oagcount)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
if (nb > mp->m_sb.sb_dblocks)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS,
nb - mp->m_sb.sb_dblocks);
if (nfree)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, nfree);
if (dpct)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
error = xfs_trans_commit(tp, 0, NULL);
if (error) {
return error;
}
/* New allocation groups fully initialized, so update mount struct */
if (nagimax)
mp->m_maxagi = nagimax;
if (mp->m_sb.sb_imax_pct) {
__uint64_t icount = mp->m_sb.sb_dblocks * mp->m_sb.sb_imax_pct;
do_div(icount, 100);
mp->m_maxicount = icount << mp->m_sb.sb_inopblog;
} else
mp->m_maxicount = 0;
for (agno = 1; agno < nagcount; agno++) {
error = xfs_read_buf(mp, mp->m_ddev_targp,
XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
XFS_FSS_TO_BB(mp, 1), 0, &bp);
if (error) {
xfs_fs_cmn_err(CE_WARN, mp,
"error %d reading secondary superblock for ag %d",
error, agno);
break;
}
sbp = XFS_BUF_TO_SBP(bp);
xfs_xlatesb(sbp, &mp->m_sb, -1, XFS_SB_ALL_BITS);
/*
* If we get an error writing out the alternate superblocks,
* just issue a warning and continue. The real work is
* already done and committed.
*/
if (!(error = xfs_bwrite(mp, bp))) {
continue;
} else {
xfs_fs_cmn_err(CE_WARN, mp,
"write error %d updating secondary superblock for ag %d",
error, agno);
break; /* no point in continuing */
}
}
return 0;
error0:
xfs_trans_cancel(tp, XFS_TRANS_ABORT);
return error;
}
static int
xfs_growfs_log_private(
xfs_mount_t *mp, /* mount point for filesystem */
xfs_growfs_log_t *in) /* growfs log input struct */
{
xfs_extlen_t nb;
nb = in->newblocks;
if (nb < XFS_MIN_LOG_BLOCKS || nb < XFS_B_TO_FSB(mp, XFS_MIN_LOG_BYTES))
return XFS_ERROR(EINVAL);
if (nb == mp->m_sb.sb_logblocks &&
in->isint == (mp->m_sb.sb_logstart != 0))
return XFS_ERROR(EINVAL);
/*
* Moving the log is hard, need new interfaces to sync
* the log first, hold off all activity while moving it.
* Can have shorter or longer log in the same space,
* or transform internal to external log or vice versa.
*/
return XFS_ERROR(ENOSYS);
}
/*
* protected versions of growfs function acquire and release locks on the mount
* point - exported through ioctls: XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG,
* XFS_IOC_FSGROWFSRT
*/
int
xfs_growfs_data(
xfs_mount_t *mp,
xfs_growfs_data_t *in)
{
int error;
if (!cpsema(&mp->m_growlock))
return XFS_ERROR(EWOULDBLOCK);
error = xfs_growfs_data_private(mp, in);
vsema(&mp->m_growlock);
return error;
}
int
xfs_growfs_log(
xfs_mount_t *mp,
xfs_growfs_log_t *in)
{
int error;
if (!cpsema(&mp->m_growlock))
return XFS_ERROR(EWOULDBLOCK);
error = xfs_growfs_log_private(mp, in);
vsema(&mp->m_growlock);
return error;
}
/*
* exported through ioctl XFS_IOC_FSCOUNTS
*/
int
xfs_fs_counts(
xfs_mount_t *mp,
xfs_fsop_counts_t *cnt)
{
unsigned long s;
xfs_icsb_sync_counters_lazy(mp);
s = XFS_SB_LOCK(mp);
cnt->freedata = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
cnt->freertx = mp->m_sb.sb_frextents;
cnt->freeino = mp->m_sb.sb_ifree;
cnt->allocino = mp->m_sb.sb_icount;
XFS_SB_UNLOCK(mp, s);
return 0;
}
/*
* exported through ioctl XFS_IOC_SET_RESBLKS & XFS_IOC_GET_RESBLKS
*
* xfs_reserve_blocks is called to set m_resblks
* in the in-core mount table. The number of unused reserved blocks
* is kept in m_resblks_avail.
*
* Reserve the requested number of blocks if available. Otherwise return
* as many as possible to satisfy the request. The actual number
* reserved are returned in outval
*
* A null inval pointer indicates that only the current reserved blocks
* available should be returned no settings are changed.
*/
int
xfs_reserve_blocks(
xfs_mount_t *mp,
__uint64_t *inval,
xfs_fsop_resblks_t *outval)
{
__int64_t lcounter, delta;
__uint64_t request;
unsigned long s;
/* If inval is null, report current values and return */
if (inval == (__uint64_t *)NULL) {
outval->resblks = mp->m_resblks;
outval->resblks_avail = mp->m_resblks_avail;
return 0;
}
request = *inval;
s = XFS_SB_LOCK(mp);
/*
* If our previous reservation was larger than the current value,
* then move any unused blocks back to the free pool.
*/
if (mp->m_resblks > request) {
lcounter = mp->m_resblks_avail - request;
if (lcounter > 0) { /* release unused blocks */
mp->m_sb.sb_fdblocks += lcounter;
mp->m_resblks_avail -= lcounter;
}
mp->m_resblks = request;
} else {
__int64_t free;
free = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
delta = request - mp->m_resblks;
lcounter = free - delta;
if (lcounter < 0) {
/* We can't satisfy the request, just get what we can */
mp->m_resblks += free;
mp->m_resblks_avail += free;
mp->m_sb.sb_fdblocks = XFS_ALLOC_SET_ASIDE(mp);
} else {
mp->m_sb.sb_fdblocks =
lcounter + XFS_ALLOC_SET_ASIDE(mp);
mp->m_resblks = request;
mp->m_resblks_avail += delta;
}
}
outval->resblks = mp->m_resblks;
outval->resblks_avail = mp->m_resblks_avail;
XFS_SB_UNLOCK(mp, s);
return 0;
}
void
xfs_fs_log_dummy(
xfs_mount_t *mp)
{
xfs_trans_t *tp;
xfs_inode_t *ip;
tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
if (xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0)) {
xfs_trans_cancel(tp, 0);
return;
}
ip = mp->m_rootip;
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_ihold(tp, ip);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
xfs_trans_set_sync(tp);
xfs_trans_commit(tp, 0, NULL);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
}
int
xfs_fs_goingdown(
xfs_mount_t *mp,
__uint32_t inflags)
{
switch (inflags) {
case XFS_FSOP_GOING_FLAGS_DEFAULT: {
struct bhv_vfs *vfsp = XFS_MTOVFS(mp);
struct super_block *sb = freeze_bdev(vfsp->vfs_super->s_bdev);
if (sb && !IS_ERR(sb)) {
xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
thaw_bdev(sb->s_bdev, sb);
}
break;
}
case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
break;
case XFS_FSOP_GOING_FLAGS_NOLOGFLUSH:
xfs_force_shutdown(mp,
SHUTDOWN_FORCE_UMOUNT | SHUTDOWN_LOG_IO_ERROR);
break;
default:
return XFS_ERROR(EINVAL);
}
return 0;
}