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b8d06fca08
Differences between how paging is done on Solaris and Linux can cause deadlocks if KM_SLEEP is used in any the following contexts. * The txg_sync thread * The zvol write/discard threads * The zpl_putpage() VFS callback This is because KM_SLEEP will allow for direct reclaim which may result in the VM calling back in to the filesystem or block layer to write out pages. If a lock is held over this operation the potential exists to deadlock the system. To ensure forward progress all memory allocations in these contexts must us KM_PUSHPAGE which disables performing any I/O to accomplish the memory allocation. Previously, this behavior was acheived by setting PF_MEMALLOC on the thread. However, that resulted in unexpected side effects such as the exhaustion of pages in ZONE_DMA. This approach touchs more of the zfs code, but it is more consistent with the right way to handle these cases under Linux. This is patch lays the ground work for being able to safely revert the following commits which used PF_MEMALLOC:21ade34Disable direct reclaim for z_wr_* threadscfc9a5cFix zpl_writepage() deadlockeec8164Fix ASSERTION(!dsl_pool_sync_context(tx->tx_pool)) Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Issue #726
70 lines
1.8 KiB
C
70 lines
1.8 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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*/
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#include <sys/bplist.h>
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#include <sys/zfs_context.h>
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void
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bplist_create(bplist_t *bpl)
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{
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mutex_init(&bpl->bpl_lock, NULL, MUTEX_DEFAULT, NULL);
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list_create(&bpl->bpl_list, sizeof (bplist_entry_t),
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offsetof(bplist_entry_t, bpe_node));
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}
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void
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bplist_destroy(bplist_t *bpl)
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{
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list_destroy(&bpl->bpl_list);
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mutex_destroy(&bpl->bpl_lock);
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}
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void
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bplist_append(bplist_t *bpl, const blkptr_t *bp)
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{
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bplist_entry_t *bpe = kmem_alloc(sizeof (*bpe), KM_PUSHPAGE);
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mutex_enter(&bpl->bpl_lock);
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bpe->bpe_blk = *bp;
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list_insert_tail(&bpl->bpl_list, bpe);
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mutex_exit(&bpl->bpl_lock);
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}
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void
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bplist_iterate(bplist_t *bpl, bplist_itor_t *func, void *arg, dmu_tx_t *tx)
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{
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bplist_entry_t *bpe;
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mutex_enter(&bpl->bpl_lock);
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while ((bpe = list_head(&bpl->bpl_list))) {
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list_remove(&bpl->bpl_list, bpe);
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mutex_exit(&bpl->bpl_lock);
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func(arg, &bpe->bpe_blk, tx);
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kmem_free(bpe, sizeof (*bpe));
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mutex_enter(&bpl->bpl_lock);
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}
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mutex_exit(&bpl->bpl_lock);
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}
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