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xfs: avoid memory allocation under m_peraglock in growfs code 

Allocate the memory for the larger m_perag array before taking the
per-AG lock as the per-AG lock can be taken under the i_lock which
can be taken from reclaim context.

Reported by the new reclaim context tracing in lockdep.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>
This commit is contained in:
Christoph Hellwig 2009-07-18 18:14:53 -04:00 committed by Felix Blyakher
parent c8a4051c37
commit 0cc6eee130
1 changed files with 14 additions and 6 deletions
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20
fs/xfs/xfs_fsops.c
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@ -167,17 +167,25 @@ xfs_growfs_data_private(
new = nb - mp->m_sb.sb_dblocks;
oagcount = mp->m_sb.sb_agcount;
if (nagcount > oagcount) {
void *new_perag, *old_perag;
xfs_filestream_flush(mp);
new_perag = kmem_zalloc(sizeof(xfs_perag_t) * nagcount,
KM_MAYFAIL);
if (!new_perag)
return XFS_ERROR(ENOMEM);
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));
memcpy(new_perag, mp->m_perag, sizeof(xfs_perag_t) * oagcount);
old_perag = mp->m_perag;
mp->m_perag = new_perag;
mp->m_flags |= XFS_MOUNT_32BITINODES;
nagimax = xfs_initialize_perag(mp, nagcount);
up_write(&mp->m_peraglock);
kmem_free(old_perag);
}
tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFS);
tp->t_flags |= XFS_TRANS_RESERVE;