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xfs: Don't directly reference m_perag in allocation code
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Start abstracting the perag references so that the indexing of the
structures is not directly coded into all the places that uses the
perag structures. This will allow us to separate the use of the
perag structure and the way it is indexed and hence avoid the known
deadlocks related to growing a busy filesystem.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
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Dave Chinner authored and Alex Elder committed Jan 15, 2010
1 parent 5017e97 commit a862e0f
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Showing 2 changed files with 53 additions and 38 deletions.
82 changes: 46 additions & 36 deletions fs/xfs/xfs_alloc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1662,11 +1662,13 @@ xfs_free_ag_extent(
xfs_agf_t *agf;
xfs_perag_t *pag; /* per allocation group data */

pag = xfs_perag_get(mp, agno);
pag->pagf_freeblks += len;
xfs_perag_put(pag);

agf = XFS_BUF_TO_AGF(agbp);
pag = &mp->m_perag[agno];
be32_add_cpu(&agf->agf_freeblks, len);
xfs_trans_agblocks_delta(tp, len);
pag->pagf_freeblks += len;
XFS_WANT_CORRUPTED_GOTO(
be32_to_cpu(agf->agf_freeblks) <=
be32_to_cpu(agf->agf_length),
Expand Down Expand Up @@ -1969,10 +1971,12 @@ xfs_alloc_get_freelist(
xfs_trans_brelse(tp, agflbp);
if (be32_to_cpu(agf->agf_flfirst) == XFS_AGFL_SIZE(mp))
agf->agf_flfirst = 0;
pag = &mp->m_perag[be32_to_cpu(agf->agf_seqno)];

pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno));
be32_add_cpu(&agf->agf_flcount, -1);
xfs_trans_agflist_delta(tp, -1);
pag->pagf_flcount--;
xfs_perag_put(pag);

logflags = XFS_AGF_FLFIRST | XFS_AGF_FLCOUNT;
if (btreeblk) {
Expand Down Expand Up @@ -2078,7 +2082,8 @@ xfs_alloc_put_freelist(
be32_add_cpu(&agf->agf_fllast, 1);
if (be32_to_cpu(agf->agf_fllast) == XFS_AGFL_SIZE(mp))
agf->agf_fllast = 0;
pag = &mp->m_perag[be32_to_cpu(agf->agf_seqno)];

pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno));
be32_add_cpu(&agf->agf_flcount, 1);
xfs_trans_agflist_delta(tp, 1);
pag->pagf_flcount++;
Expand All @@ -2089,6 +2094,7 @@ xfs_alloc_put_freelist(
pag->pagf_btreeblks--;
logflags |= XFS_AGF_BTREEBLKS;
}
xfs_perag_put(pag);

xfs_alloc_log_agf(tp, agbp, logflags);

Expand Down Expand Up @@ -2152,7 +2158,6 @@ xfs_read_agf(
xfs_trans_brelse(tp, *bpp);
return XFS_ERROR(EFSCORRUPTED);
}

XFS_BUF_SET_VTYPE_REF(*bpp, B_FS_AGF, XFS_AGF_REF);
return 0;
}
Expand Down Expand Up @@ -2184,7 +2189,7 @@ xfs_alloc_read_agf(
ASSERT(!XFS_BUF_GETERROR(*bpp));

agf = XFS_BUF_TO_AGF(*bpp);
pag = &mp->m_perag[agno];
pag = xfs_perag_get(mp, agno);
if (!pag->pagf_init) {
pag->pagf_freeblks = be32_to_cpu(agf->agf_freeblks);
pag->pagf_btreeblks = be32_to_cpu(agf->agf_btreeblks);
Expand All @@ -2211,6 +2216,7 @@ xfs_alloc_read_agf(
be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]));
}
#endif
xfs_perag_put(pag);
return 0;
}

Expand Down Expand Up @@ -2271,7 +2277,7 @@ xfs_alloc_vextent(
*/
args->agno = XFS_FSB_TO_AGNO(mp, args->fsbno);
down_read(&mp->m_peraglock);
args->pag = &mp->m_perag[args->agno];
args->pag = xfs_perag_get(mp, args->agno);
args->minleft = 0;
error = xfs_alloc_fix_freelist(args, 0);
args->minleft = minleft;
Expand Down Expand Up @@ -2341,7 +2347,7 @@ xfs_alloc_vextent(
*/
down_read(&mp->m_peraglock);
for (;;) {
args->pag = &mp->m_perag[args->agno];
args->pag = xfs_perag_get(mp, args->agno);
if (no_min) args->minleft = 0;
error = xfs_alloc_fix_freelist(args, flags);
args->minleft = minleft;
Expand Down Expand Up @@ -2400,6 +2406,7 @@ xfs_alloc_vextent(
}
}
}
xfs_perag_put(args->pag);
}
up_read(&mp->m_peraglock);
if (bump_rotor || (type == XFS_ALLOCTYPE_ANY_AG)) {
Expand Down Expand Up @@ -2427,8 +2434,10 @@ xfs_alloc_vextent(
args->len);
#endif
}
xfs_perag_put(args->pag);
return 0;
error0:
xfs_perag_put(args->pag);
up_read(&mp->m_peraglock);
return error;
}
Expand All @@ -2455,7 +2464,7 @@ xfs_free_extent(
ASSERT(args.agno < args.mp->m_sb.sb_agcount);
args.agbno = XFS_FSB_TO_AGBNO(args.mp, bno);
down_read(&args.mp->m_peraglock);
args.pag = &args.mp->m_perag[args.agno];
args.pag = xfs_perag_get(args.mp, args.agno);
if ((error = xfs_alloc_fix_freelist(&args, XFS_ALLOC_FLAG_FREEING)))
goto error0;
#ifdef DEBUG
Expand All @@ -2465,6 +2474,7 @@ xfs_free_extent(
#endif
error = xfs_free_ag_extent(tp, args.agbp, args.agno, args.agbno, len, 0);
error0:
xfs_perag_put(args.pag);
up_read(&args.mp->m_peraglock);
return error;
}
Expand All @@ -2486,27 +2496,27 @@ xfs_alloc_mark_busy(xfs_trans_t *tp,
xfs_agblock_t bno,
xfs_extlen_t len)
{
xfs_mount_t *mp;
xfs_perag_busy_t *bsy;
struct xfs_perag *pag;
int n;

mp = tp->t_mountp;
spin_lock(&mp->m_perag[agno].pagb_lock);
pag = xfs_perag_get(tp->t_mountp, agno);
spin_lock(&pag->pagb_lock);

/* search pagb_list for an open slot */
for (bsy = mp->m_perag[agno].pagb_list, n = 0;
for (bsy = pag->pagb_list, n = 0;
n < XFS_PAGB_NUM_SLOTS;
bsy++, n++) {
if (bsy->busy_tp == NULL) {
break;
}
}

trace_xfs_alloc_busy(mp, agno, bno, len, n);
trace_xfs_alloc_busy(tp->t_mountp, agno, bno, len, n);

if (n < XFS_PAGB_NUM_SLOTS) {
bsy = &mp->m_perag[agno].pagb_list[n];
mp->m_perag[agno].pagb_count++;
bsy = &pag->pagb_list[n];
pag->pagb_count++;
bsy->busy_start = bno;
bsy->busy_length = len;
bsy->busy_tp = tp;
Expand All @@ -2521,32 +2531,32 @@ xfs_alloc_mark_busy(xfs_trans_t *tp,
xfs_trans_set_sync(tp);
}

spin_unlock(&mp->m_perag[agno].pagb_lock);
spin_unlock(&pag->pagb_lock);
xfs_perag_put(pag);
}

void
xfs_alloc_clear_busy(xfs_trans_t *tp,
xfs_agnumber_t agno,
int idx)
{
xfs_mount_t *mp;
struct xfs_perag *pag;
xfs_perag_busy_t *list;

mp = tp->t_mountp;

spin_lock(&mp->m_perag[agno].pagb_lock);
list = mp->m_perag[agno].pagb_list;

ASSERT(idx < XFS_PAGB_NUM_SLOTS);
pag = xfs_perag_get(tp->t_mountp, agno);
spin_lock(&pag->pagb_lock);
list = pag->pagb_list;

trace_xfs_alloc_unbusy(mp, agno, idx, list[idx].busy_tp == tp);
trace_xfs_alloc_unbusy(tp->t_mountp, agno, idx, list[idx].busy_tp == tp);

if (list[idx].busy_tp == tp) {
list[idx].busy_tp = NULL;
mp->m_perag[agno].pagb_count--;
pag->pagb_count--;
}

spin_unlock(&mp->m_perag[agno].pagb_lock);
spin_unlock(&pag->pagb_lock);
xfs_perag_put(pag);
}


Expand All @@ -2560,26 +2570,25 @@ xfs_alloc_search_busy(xfs_trans_t *tp,
xfs_agblock_t bno,
xfs_extlen_t len)
{
xfs_mount_t *mp;
struct xfs_perag *pag;
xfs_perag_busy_t *bsy;
xfs_agblock_t uend, bend;
xfs_lsn_t lsn = 0;
int cnt;

mp = tp->t_mountp;

spin_lock(&mp->m_perag[agno].pagb_lock);

uend = bno + len - 1;
pag = xfs_perag_get(tp->t_mountp, agno);
spin_lock(&pag->pagb_lock);
cnt = pag->pagb_count;

/*
* search pagb_list for this slot, skipping open slots. We have to
* search the entire array as there may be multiple overlaps and
* we have to get the most recent LSN for the log force to push out
* all the transactions that span the range.
*/
for (cnt = 0; cnt < mp->m_perag[agno].pagb_count; cnt++) {
bsy = &mp->m_perag[agno].pagb_list[cnt];
uend = bno + len - 1;
for (cnt = 0; cnt < pag->pagb_count; cnt++) {
bsy = &pag->pagb_list[cnt];
if (!bsy->busy_tp)
continue;

Expand All @@ -2591,13 +2600,14 @@ xfs_alloc_search_busy(xfs_trans_t *tp,
if (XFS_LSN_CMP(bsy->busy_tp->t_commit_lsn, lsn) > 0)
lsn = bsy->busy_tp->t_commit_lsn;
}
spin_unlock(&mp->m_perag[agno].pagb_lock);
spin_unlock(&pag->pagb_lock);
xfs_perag_put(pag);
trace_xfs_alloc_busysearch(tp->t_mountp, agno, bno, len, lsn);

/*
* If a block was found, force the log through the LSN of the
* transaction that freed the block
*/
if (lsn)
xfs_log_force(mp, lsn, XFS_LOG_FORCE|XFS_LOG_SYNC);
xfs_log_force(tp->t_mountp, lsn, XFS_LOG_FORCE|XFS_LOG_SYNC);
}
9 changes: 7 additions & 2 deletions fs/xfs/xfs_alloc_btree.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,12 +61,14 @@ xfs_allocbt_set_root(
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);
cur->bc_mp->m_perag[seqno].pagf_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);
}
Expand Down Expand Up @@ -150,6 +152,7 @@ xfs_allocbt_update_lastrec(
{
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;

Expand Down Expand Up @@ -193,7 +196,9 @@ xfs_allocbt_update_lastrec(
}

agf->agf_longest = len;
cur->bc_mp->m_perag[seqno].pagf_longest = be32_to_cpu(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);
}

Expand Down

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