606 lines
15 KiB
C
606 lines
15 KiB
C
/*
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* Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
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* Copyright (c) 2010 David Chinner.
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* Copyright (c) 2011 Christoph Hellwig.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "xfs.h"
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#include "xfs_fs.h"
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#include "xfs_format.h"
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#include "xfs_log_format.h"
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#include "xfs_shared.h"
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#include "xfs_trans_resv.h"
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#include "xfs_sb.h"
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#include "xfs_ag.h"
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#include "xfs_mount.h"
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#include "xfs_alloc.h"
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#include "xfs_extent_busy.h"
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#include "xfs_trace.h"
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#include "xfs_trans.h"
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#include "xfs_log.h"
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void
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xfs_extent_busy_insert(
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struct xfs_trans *tp,
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xfs_agnumber_t agno,
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xfs_agblock_t bno,
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xfs_extlen_t len,
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unsigned int flags)
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{
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struct xfs_extent_busy *new;
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struct xfs_extent_busy *busyp;
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struct xfs_perag *pag;
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struct rb_node **rbp;
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struct rb_node *parent = NULL;
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new = kmem_zalloc(sizeof(struct xfs_extent_busy), KM_MAYFAIL);
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if (!new) {
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/*
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* No Memory! Since it is now not possible to track the free
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* block, make this a synchronous transaction to insure that
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* the block is not reused before this transaction commits.
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*/
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trace_xfs_extent_busy_enomem(tp->t_mountp, agno, bno, len);
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xfs_trans_set_sync(tp);
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return;
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}
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new->agno = agno;
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new->bno = bno;
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new->length = len;
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INIT_LIST_HEAD(&new->list);
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new->flags = flags;
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/* trace before insert to be able to see failed inserts */
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trace_xfs_extent_busy(tp->t_mountp, agno, bno, len);
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pag = xfs_perag_get(tp->t_mountp, new->agno);
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spin_lock(&pag->pagb_lock);
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rbp = &pag->pagb_tree.rb_node;
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while (*rbp) {
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parent = *rbp;
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busyp = rb_entry(parent, struct xfs_extent_busy, rb_node);
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if (new->bno < busyp->bno) {
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rbp = &(*rbp)->rb_left;
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ASSERT(new->bno + new->length <= busyp->bno);
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} else if (new->bno > busyp->bno) {
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rbp = &(*rbp)->rb_right;
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ASSERT(bno >= busyp->bno + busyp->length);
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} else {
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ASSERT(0);
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}
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}
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rb_link_node(&new->rb_node, parent, rbp);
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rb_insert_color(&new->rb_node, &pag->pagb_tree);
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list_add(&new->list, &tp->t_busy);
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spin_unlock(&pag->pagb_lock);
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xfs_perag_put(pag);
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}
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/*
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* Search for a busy extent within the range of the extent we are about to
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* allocate. You need to be holding the busy extent tree lock when calling
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* xfs_extent_busy_search(). This function returns 0 for no overlapping busy
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* extent, -1 for an overlapping but not exact busy extent, and 1 for an exact
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* match. This is done so that a non-zero return indicates an overlap that
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* will require a synchronous transaction, but it can still be
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* used to distinguish between a partial or exact match.
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*/
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int
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xfs_extent_busy_search(
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struct xfs_mount *mp,
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xfs_agnumber_t agno,
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xfs_agblock_t bno,
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xfs_extlen_t len)
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{
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struct xfs_perag *pag;
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struct rb_node *rbp;
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struct xfs_extent_busy *busyp;
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int match = 0;
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pag = xfs_perag_get(mp, agno);
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spin_lock(&pag->pagb_lock);
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rbp = pag->pagb_tree.rb_node;
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/* find closest start bno overlap */
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while (rbp) {
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busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node);
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if (bno < busyp->bno) {
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/* may overlap, but exact start block is lower */
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if (bno + len > busyp->bno)
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match = -1;
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rbp = rbp->rb_left;
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} else if (bno > busyp->bno) {
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/* may overlap, but exact start block is higher */
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if (bno < busyp->bno + busyp->length)
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match = -1;
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rbp = rbp->rb_right;
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} else {
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/* bno matches busyp, length determines exact match */
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match = (busyp->length == len) ? 1 : -1;
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break;
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}
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}
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spin_unlock(&pag->pagb_lock);
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xfs_perag_put(pag);
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return match;
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}
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/*
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* The found free extent [fbno, fend] overlaps part or all of the given busy
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* extent. If the overlap covers the beginning, the end, or all of the busy
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* extent, the overlapping portion can be made unbusy and used for the
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* allocation. We can't split a busy extent because we can't modify a
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* transaction/CIL context busy list, but we can update an entry's block
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* number or length.
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*
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* Returns true if the extent can safely be reused, or false if the search
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* needs to be restarted.
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*/
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STATIC bool
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xfs_extent_busy_update_extent(
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struct xfs_mount *mp,
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struct xfs_perag *pag,
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struct xfs_extent_busy *busyp,
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xfs_agblock_t fbno,
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xfs_extlen_t flen,
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bool userdata) __releases(&pag->pagb_lock)
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__acquires(&pag->pagb_lock)
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{
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xfs_agblock_t fend = fbno + flen;
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xfs_agblock_t bbno = busyp->bno;
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xfs_agblock_t bend = bbno + busyp->length;
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/*
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* This extent is currently being discarded. Give the thread
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* performing the discard a chance to mark the extent unbusy
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* and retry.
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*/
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if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) {
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spin_unlock(&pag->pagb_lock);
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delay(1);
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spin_lock(&pag->pagb_lock);
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return false;
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}
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/*
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* If there is a busy extent overlapping a user allocation, we have
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* no choice but to force the log and retry the search.
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*
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* Fortunately this does not happen during normal operation, but
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* only if the filesystem is very low on space and has to dip into
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* the AGFL for normal allocations.
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*/
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if (userdata)
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goto out_force_log;
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if (bbno < fbno && bend > fend) {
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/*
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* Case 1:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +---------+
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* fbno fend
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*/
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/*
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* We would have to split the busy extent to be able to track
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* it correct, which we cannot do because we would have to
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* modify the list of busy extents attached to the transaction
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* or CIL context, which is immutable.
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*
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* Force out the log to clear the busy extent and retry the
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* search.
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*/
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goto out_force_log;
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} else if (bbno >= fbno && bend <= fend) {
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/*
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* Case 2:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +-----------------+
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* fbno fend
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*
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* Case 3:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +--------------------------+
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* fbno fend
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*
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* Case 4:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +--------------------------+
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* fbno fend
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*
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* Case 5:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +-----------------------------------+
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* fbno fend
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*
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*/
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/*
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* The busy extent is fully covered by the extent we are
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* allocating, and can simply be removed from the rbtree.
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* However we cannot remove it from the immutable list
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* tracking busy extents in the transaction or CIL context,
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* so set the length to zero to mark it invalid.
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*
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* We also need to restart the busy extent search from the
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* tree root, because erasing the node can rearrange the
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* tree topology.
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*/
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rb_erase(&busyp->rb_node, &pag->pagb_tree);
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busyp->length = 0;
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return false;
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} else if (fend < bend) {
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/*
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* Case 6:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +---------+
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* fbno fend
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*
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* Case 7:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +------------------+
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* fbno fend
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*
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*/
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busyp->bno = fend;
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} else if (bbno < fbno) {
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/*
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* Case 8:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +-------------+
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* fbno fend
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*
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* Case 9:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +----------------------+
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* fbno fend
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*/
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busyp->length = fbno - busyp->bno;
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} else {
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ASSERT(0);
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}
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trace_xfs_extent_busy_reuse(mp, pag->pag_agno, fbno, flen);
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return true;
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out_force_log:
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spin_unlock(&pag->pagb_lock);
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xfs_log_force(mp, XFS_LOG_SYNC);
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trace_xfs_extent_busy_force(mp, pag->pag_agno, fbno, flen);
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spin_lock(&pag->pagb_lock);
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return false;
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}
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/*
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* For a given extent [fbno, flen], make sure we can reuse it safely.
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*/
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void
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xfs_extent_busy_reuse(
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struct xfs_mount *mp,
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xfs_agnumber_t agno,
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xfs_agblock_t fbno,
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xfs_extlen_t flen,
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bool userdata)
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{
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struct xfs_perag *pag;
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struct rb_node *rbp;
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ASSERT(flen > 0);
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pag = xfs_perag_get(mp, agno);
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spin_lock(&pag->pagb_lock);
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restart:
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rbp = pag->pagb_tree.rb_node;
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while (rbp) {
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struct xfs_extent_busy *busyp =
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rb_entry(rbp, struct xfs_extent_busy, rb_node);
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xfs_agblock_t bbno = busyp->bno;
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xfs_agblock_t bend = bbno + busyp->length;
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if (fbno + flen <= bbno) {
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rbp = rbp->rb_left;
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continue;
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} else if (fbno >= bend) {
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rbp = rbp->rb_right;
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continue;
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}
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if (!xfs_extent_busy_update_extent(mp, pag, busyp, fbno, flen,
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userdata))
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goto restart;
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}
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spin_unlock(&pag->pagb_lock);
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xfs_perag_put(pag);
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}
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/*
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* For a given extent [fbno, flen], search the busy extent list to find a
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* subset of the extent that is not busy. If *rlen is smaller than
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* args->minlen no suitable extent could be found, and the higher level
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* code needs to force out the log and retry the allocation.
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*/
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void
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xfs_extent_busy_trim(
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struct xfs_alloc_arg *args,
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xfs_agblock_t bno,
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xfs_extlen_t len,
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xfs_agblock_t *rbno,
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xfs_extlen_t *rlen)
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{
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xfs_agblock_t fbno;
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xfs_extlen_t flen;
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struct rb_node *rbp;
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ASSERT(len > 0);
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spin_lock(&args->pag->pagb_lock);
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restart:
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fbno = bno;
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flen = len;
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rbp = args->pag->pagb_tree.rb_node;
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while (rbp && flen >= args->minlen) {
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struct xfs_extent_busy *busyp =
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rb_entry(rbp, struct xfs_extent_busy, rb_node);
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xfs_agblock_t fend = fbno + flen;
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xfs_agblock_t bbno = busyp->bno;
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xfs_agblock_t bend = bbno + busyp->length;
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if (fend <= bbno) {
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rbp = rbp->rb_left;
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continue;
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} else if (fbno >= bend) {
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rbp = rbp->rb_right;
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continue;
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}
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/*
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* If this is a metadata allocation, try to reuse the busy
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* extent instead of trimming the allocation.
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*/
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if (!args->userdata &&
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!(busyp->flags & XFS_EXTENT_BUSY_DISCARDED)) {
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if (!xfs_extent_busy_update_extent(args->mp, args->pag,
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busyp, fbno, flen,
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false))
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goto restart;
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continue;
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}
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if (bbno <= fbno) {
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/* start overlap */
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/*
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* Case 1:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +---------+
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* fbno fend
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*
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* Case 2:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +-------------+
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* fbno fend
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*
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* Case 3:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +-------------+
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* fbno fend
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*
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* Case 4:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +-----------------+
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* fbno fend
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*
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* No unbusy region in extent, return failure.
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*/
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if (fend <= bend)
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goto fail;
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/*
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* Case 5:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +----------------------+
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* fbno fend
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*
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* Case 6:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +--------------------------+
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* fbno fend
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*
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* Needs to be trimmed to:
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* +-------+
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* fbno fend
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*/
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fbno = bend;
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} else if (bend >= fend) {
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/* end overlap */
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/*
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* Case 7:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +------------------+
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* fbno fend
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*
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* Case 8:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +--------------------------+
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* fbno fend
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*
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* Needs to be trimmed to:
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* +-------+
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* fbno fend
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*/
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fend = bbno;
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} else {
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/* middle overlap */
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/*
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* Case 9:
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* bbno bend
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* +BBBBBBBBBBBBBBBBB+
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* +-----------------------------------+
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* fbno fend
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*
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* Can be trimmed to:
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* +-------+ OR +-------+
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* fbno fend fbno fend
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*
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* Backward allocation leads to significant
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* fragmentation of directories, which degrades
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* directory performance, therefore we always want to
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* choose the option that produces forward allocation
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* patterns.
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* Preferring the lower bno extent will make the next
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* request use "fend" as the start of the next
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* allocation; if the segment is no longer busy at
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* that point, we'll get a contiguous allocation, but
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* even if it is still busy, we will get a forward
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* allocation.
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* We try to avoid choosing the segment at "bend",
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* because that can lead to the next allocation
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* taking the segment at "fbno", which would be a
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* backward allocation. We only use the segment at
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* "fbno" if it is much larger than the current
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* requested size, because in that case there's a
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* good chance subsequent allocations will be
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* contiguous.
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*/
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if (bbno - fbno >= args->maxlen) {
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/* left candidate fits perfect */
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fend = bbno;
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} else if (fend - bend >= args->maxlen * 4) {
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/* right candidate has enough free space */
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fbno = bend;
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} else if (bbno - fbno >= args->minlen) {
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/* left candidate fits minimum requirement */
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fend = bbno;
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} else {
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goto fail;
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}
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}
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flen = fend - fbno;
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}
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spin_unlock(&args->pag->pagb_lock);
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if (fbno != bno || flen != len) {
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trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len,
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fbno, flen);
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}
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*rbno = fbno;
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*rlen = flen;
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return;
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fail:
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/*
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* Return a zero extent length as failure indications. All callers
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* re-check if the trimmed extent satisfies the minlen requirement.
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*/
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spin_unlock(&args->pag->pagb_lock);
|
|
trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len, fbno, 0);
|
|
*rbno = fbno;
|
|
*rlen = 0;
|
|
}
|
|
|
|
STATIC void
|
|
xfs_extent_busy_clear_one(
|
|
struct xfs_mount *mp,
|
|
struct xfs_perag *pag,
|
|
struct xfs_extent_busy *busyp)
|
|
{
|
|
if (busyp->length) {
|
|
trace_xfs_extent_busy_clear(mp, busyp->agno, busyp->bno,
|
|
busyp->length);
|
|
rb_erase(&busyp->rb_node, &pag->pagb_tree);
|
|
}
|
|
|
|
list_del_init(&busyp->list);
|
|
kmem_free(busyp);
|
|
}
|
|
|
|
/*
|
|
* Remove all extents on the passed in list from the busy extents tree.
|
|
* If do_discard is set skip extents that need to be discarded, and mark
|
|
* these as undergoing a discard operation instead.
|
|
*/
|
|
void
|
|
xfs_extent_busy_clear(
|
|
struct xfs_mount *mp,
|
|
struct list_head *list,
|
|
bool do_discard)
|
|
{
|
|
struct xfs_extent_busy *busyp, *n;
|
|
struct xfs_perag *pag = NULL;
|
|
xfs_agnumber_t agno = NULLAGNUMBER;
|
|
|
|
list_for_each_entry_safe(busyp, n, list, list) {
|
|
if (busyp->agno != agno) {
|
|
if (pag) {
|
|
spin_unlock(&pag->pagb_lock);
|
|
xfs_perag_put(pag);
|
|
}
|
|
pag = xfs_perag_get(mp, busyp->agno);
|
|
spin_lock(&pag->pagb_lock);
|
|
agno = busyp->agno;
|
|
}
|
|
|
|
if (do_discard && busyp->length &&
|
|
!(busyp->flags & XFS_EXTENT_BUSY_SKIP_DISCARD))
|
|
busyp->flags = XFS_EXTENT_BUSY_DISCARDED;
|
|
else
|
|
xfs_extent_busy_clear_one(mp, pag, busyp);
|
|
}
|
|
|
|
if (pag) {
|
|
spin_unlock(&pag->pagb_lock);
|
|
xfs_perag_put(pag);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Callback for list_sort to sort busy extents by the AG they reside in.
|
|
*/
|
|
int
|
|
xfs_extent_busy_ag_cmp(
|
|
void *priv,
|
|
struct list_head *a,
|
|
struct list_head *b)
|
|
{
|
|
return container_of(a, struct xfs_extent_busy, list)->agno -
|
|
container_of(b, struct xfs_extent_busy, list)->agno;
|
|
}
|