2cc7d26f7f
file are after snaplock, while other ffs device buffers are before snaplock in global lock order. By itself, this could cause deadlock when bdwrite() tries to flush dirty buffers on snapshotted ffs. If, during the flush, COW activity for snapshot needs to allocate block and ffs_alloccg() selects the cylinder group that is being written by bdwrite(), then kernel would panic due to recursive buffer lock acquision. Avoid dealing with buffers in bdwrite() that are from other side of snaplock divisor in the lock order then the buffer being written. Add new BOP, bop_bdwrite(), to do dirty buffer flushing for same vnode in the bdwrite(). Default implementation, bufbdflush(), refactors the code from bdwrite(). For ffs device buffers, specialized implementation is used. Reviewed by: tegge, jeff, Russell Cattelan (cattelan xfs org, xfs changes) Tested by: Peter Holm X-MFC after: 3 weeks (if ever: it changes ABI)
140 lines
4.8 KiB
C
140 lines
4.8 KiB
C
/*-
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* Copyright (c) 2004 Poul-Henning Kamp
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Architectural notes:
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*
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* bufobj is a new object which is what buffers hang from in the buffer
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* cache.
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*
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* This used to be vnodes, but we need non-vnode code to be able
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* to use the buffer cache as well, specifically geom classes like gbde,
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* raid3 and raid5.
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*
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* All vnodes will contain a bufobj initially, but down the road we may
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* want to only allocate bufobjs when they are needed. There could be a
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* large number of vnodes in the system which wouldn't need a bufobj during
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* their lifetime.
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*
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* The exact relationship to the vmobject is not determined at this point,
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* it may in fact be that we find them to be two sides of the same object
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* once things starts to crystalize.
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*/
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#ifndef _SYS_BUFOBJ_H_
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#define _SYS_BUFOBJ_H_
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#if defined(_KERNEL) || defined(_KVM_VNODE)
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#include <sys/queue.h>
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struct bufobj;
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struct buf_ops;
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extern struct buf_ops buf_ops_bio;
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TAILQ_HEAD(buflists, buf);
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/* A Buffer splay list */
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struct bufv {
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struct buflists bv_hd; /* Sorted blocklist */
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struct buf *bv_root; /* Buf splay tree */
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int bv_cnt; /* Number of buffers */
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};
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typedef void b_strategy_t(struct bufobj *, struct buf *);
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typedef int b_write_t(struct buf *);
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typedef int b_sync_t(struct bufobj *, int waitfor, struct thread *td);
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typedef void b_bdflush_t(struct bufobj *, struct buf *);
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struct buf_ops {
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char *bop_name;
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b_write_t *bop_write;
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b_strategy_t *bop_strategy;
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b_sync_t *bop_sync;
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b_bdflush_t *bop_bdflush;
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};
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#define BO_STRATEGY(bo, bp) ((bo)->bo_ops->bop_strategy((bo), (bp)))
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#define BO_SYNC(bo, w, td) ((bo)->bo_ops->bop_sync((bo), (w), (td)))
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#define BO_WRITE(bo, bp) ((bo)->bo_ops->bop_write((bp)))
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#define BO_BDFLUSH(bo, bp) ((bo)->bo_ops->bop_bdflush((bo), (bp)))
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struct bufobj {
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struct mtx *bo_mtx; /* Mutex which protects "i" things */
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struct bufv bo_clean; /* i Clean buffers */
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struct bufv bo_dirty; /* i Dirty buffers */
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long bo_numoutput; /* i Writes in progress */
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u_int bo_flag; /* i Flags */
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struct buf_ops *bo_ops; /* - Buffer operations */
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int bo_bsize; /* - Block size for i/o */
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struct vm_object *bo_object; /* v Place to store VM object */
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LIST_ENTRY(bufobj) bo_synclist; /* S dirty vnode list */
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void *bo_private; /* private pointer */
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struct vnode *__bo_vnode; /*
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* XXX: This vnode pointer is here
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* XXX: only to keep the syncer working
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* XXX: for now.
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*/
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};
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/*
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* XXX BO_ONWORKLST could be replaced with a check for NULL list elements
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* in v_synclist.
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*/
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#define BO_ONWORKLST (1 << 0) /* On syncer work-list */
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#define BO_WWAIT (1 << 1) /* Wait for output to complete */
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#define BO_NEEDSGIANT (1 << 2) /* Require giant for child buffers. */
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#define BO_LOCK(bo) \
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do { \
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KASSERT((bo)->bo_mtx != NULL, ("No lock in bufobj")); \
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mtx_lock((bo)->bo_mtx); \
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} while (0)
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#define BO_UNLOCK(bo) \
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do { \
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KASSERT((bo)->bo_mtx != NULL, ("No lock in bufobj")); \
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mtx_unlock((bo)->bo_mtx); \
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} while (0)
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#define BO_MTX(bo) ((bo)->bo_mtx)
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#define ASSERT_BO_LOCKED(bo) mtx_assert(bo->bo_mtx, MA_OWNED)
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#define ASSERT_BO_UNLOCKED(bo) mtx_assert(bo->bo_mtx, MA_NOTOWNED)
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void bufobj_wdrop(struct bufobj *bo);
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void bufobj_wref(struct bufobj *bo);
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void bufobj_wrefl(struct bufobj *bo);
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int bufobj_invalbuf(struct bufobj *bo, int flags, struct thread *td, int slpflag, int slptimeo);
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int bufobj_wwait(struct bufobj *bo, int slpflag, int timeo);
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int bufsync(struct bufobj *bo, int waitfor, struct thread *td);
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void bufbdflush(struct bufobj *bo, struct buf *bp);
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#endif /* defined(_KERNEL) || defined(_KVM_VNODE) */
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#endif /* _SYS_BUFOBJ_H_ */
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