From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- fs/xfs/xfs_extent_busy.c | 604 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 604 insertions(+) create mode 100644 fs/xfs/xfs_extent_busy.c (limited to 'fs/xfs/xfs_extent_busy.c') diff --git a/fs/xfs/xfs_extent_busy.c b/fs/xfs/xfs_extent_busy.c new file mode 100644 index 000000000..c263e0792 --- /dev/null +++ b/fs/xfs/xfs_extent_busy.c @@ -0,0 +1,604 @@ +/* + * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc. + * Copyright (c) 2010 David Chinner. + * Copyright (c) 2011 Christoph Hellwig. + * All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it would be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ +#include "xfs.h" +#include "xfs_fs.h" +#include "xfs_format.h" +#include "xfs_log_format.h" +#include "xfs_shared.h" +#include "xfs_trans_resv.h" +#include "xfs_sb.h" +#include "xfs_mount.h" +#include "xfs_alloc.h" +#include "xfs_extent_busy.h" +#include "xfs_trace.h" +#include "xfs_trans.h" +#include "xfs_log.h" + +void +xfs_extent_busy_insert( + struct xfs_trans *tp, + xfs_agnumber_t agno, + xfs_agblock_t bno, + xfs_extlen_t len, + unsigned int flags) +{ + struct xfs_extent_busy *new; + struct xfs_extent_busy *busyp; + struct xfs_perag *pag; + struct rb_node **rbp; + struct rb_node *parent = NULL; + + new = kmem_zalloc(sizeof(struct xfs_extent_busy), KM_MAYFAIL); + if (!new) { + /* + * No Memory! Since it is now not possible to track the free + * block, make this a synchronous transaction to insure that + * the block is not reused before this transaction commits. + */ + trace_xfs_extent_busy_enomem(tp->t_mountp, agno, bno, len); + xfs_trans_set_sync(tp); + return; + } + + new->agno = agno; + new->bno = bno; + new->length = len; + INIT_LIST_HEAD(&new->list); + new->flags = flags; + + /* trace before insert to be able to see failed inserts */ + trace_xfs_extent_busy(tp->t_mountp, agno, bno, len); + + pag = xfs_perag_get(tp->t_mountp, new->agno); + spin_lock(&pag->pagb_lock); + rbp = &pag->pagb_tree.rb_node; + while (*rbp) { + parent = *rbp; + busyp = rb_entry(parent, struct xfs_extent_busy, rb_node); + + if (new->bno < busyp->bno) { + rbp = &(*rbp)->rb_left; + ASSERT(new->bno + new->length <= busyp->bno); + } else if (new->bno > busyp->bno) { + rbp = &(*rbp)->rb_right; + ASSERT(bno >= busyp->bno + busyp->length); + } else { + ASSERT(0); + } + } + + rb_link_node(&new->rb_node, parent, rbp); + rb_insert_color(&new->rb_node, &pag->pagb_tree); + + list_add(&new->list, &tp->t_busy); + spin_unlock(&pag->pagb_lock); + xfs_perag_put(pag); +} + +/* + * Search for a busy extent within the range of the extent we are about to + * allocate. You need to be holding the busy extent tree lock when calling + * xfs_extent_busy_search(). This function returns 0 for no overlapping busy + * extent, -1 for an overlapping but not exact busy extent, and 1 for an exact + * match. This is done so that a non-zero return indicates an overlap that + * will require a synchronous transaction, but it can still be + * used to distinguish between a partial or exact match. + */ +int +xfs_extent_busy_search( + struct xfs_mount *mp, + xfs_agnumber_t agno, + xfs_agblock_t bno, + xfs_extlen_t len) +{ + struct xfs_perag *pag; + struct rb_node *rbp; + struct xfs_extent_busy *busyp; + int match = 0; + + pag = xfs_perag_get(mp, agno); + spin_lock(&pag->pagb_lock); + + rbp = pag->pagb_tree.rb_node; + + /* find closest start bno overlap */ + while (rbp) { + busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node); + if (bno < busyp->bno) { + /* may overlap, but exact start block is lower */ + if (bno + len > busyp->bno) + match = -1; + rbp = rbp->rb_left; + } else if (bno > busyp->bno) { + /* may overlap, but exact start block is higher */ + if (bno < busyp->bno + busyp->length) + match = -1; + rbp = rbp->rb_right; + } else { + /* bno matches busyp, length determines exact match */ + match = (busyp->length == len) ? 1 : -1; + break; + } + } + spin_unlock(&pag->pagb_lock); + xfs_perag_put(pag); + return match; +} + +/* + * The found free extent [fbno, fend] overlaps part or all of the given busy + * extent. If the overlap covers the beginning, the end, or all of the busy + * extent, the overlapping portion can be made unbusy and used for the + * allocation. We can't split a busy extent because we can't modify a + * transaction/CIL context busy list, but we can update an entry's block + * number or length. + * + * Returns true if the extent can safely be reused, or false if the search + * needs to be restarted. + */ +STATIC bool +xfs_extent_busy_update_extent( + struct xfs_mount *mp, + struct xfs_perag *pag, + struct xfs_extent_busy *busyp, + xfs_agblock_t fbno, + xfs_extlen_t flen, + bool userdata) __releases(&pag->pagb_lock) + __acquires(&pag->pagb_lock) +{ + xfs_agblock_t fend = fbno + flen; + xfs_agblock_t bbno = busyp->bno; + xfs_agblock_t bend = bbno + busyp->length; + + /* + * This extent is currently being discarded. Give the thread + * performing the discard a chance to mark the extent unbusy + * and retry. + */ + if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) { + spin_unlock(&pag->pagb_lock); + delay(1); + spin_lock(&pag->pagb_lock); + return false; + } + + /* + * If there is a busy extent overlapping a user allocation, we have + * no choice but to force the log and retry the search. + * + * Fortunately this does not happen during normal operation, but + * only if the filesystem is very low on space and has to dip into + * the AGFL for normal allocations. + */ + if (userdata) + goto out_force_log; + + if (bbno < fbno && bend > fend) { + /* + * Case 1: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +---------+ + * fbno fend + */ + + /* + * We would have to split the busy extent to be able to track + * it correct, which we cannot do because we would have to + * modify the list of busy extents attached to the transaction + * or CIL context, which is immutable. + * + * Force out the log to clear the busy extent and retry the + * search. + */ + goto out_force_log; + } else if (bbno >= fbno && bend <= fend) { + /* + * Case 2: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------+ + * fbno fend + * + * Case 3: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Case 4: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Case 5: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------------------------+ + * fbno fend + * + */ + + /* + * The busy extent is fully covered by the extent we are + * allocating, and can simply be removed from the rbtree. + * However we cannot remove it from the immutable list + * tracking busy extents in the transaction or CIL context, + * so set the length to zero to mark it invalid. + * + * We also need to restart the busy extent search from the + * tree root, because erasing the node can rearrange the + * tree topology. + */ + rb_erase(&busyp->rb_node, &pag->pagb_tree); + busyp->length = 0; + return false; + } else if (fend < bend) { + /* + * Case 6: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +---------+ + * fbno fend + * + * Case 7: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +------------------+ + * fbno fend + * + */ + busyp->bno = fend; + } else if (bbno < fbno) { + /* + * Case 8: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-------------+ + * fbno fend + * + * Case 9: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +----------------------+ + * fbno fend + */ + busyp->length = fbno - busyp->bno; + } else { + ASSERT(0); + } + + trace_xfs_extent_busy_reuse(mp, pag->pag_agno, fbno, flen); + return true; + +out_force_log: + spin_unlock(&pag->pagb_lock); + xfs_log_force(mp, XFS_LOG_SYNC); + trace_xfs_extent_busy_force(mp, pag->pag_agno, fbno, flen); + spin_lock(&pag->pagb_lock); + return false; +} + + +/* + * For a given extent [fbno, flen], make sure we can reuse it safely. + */ +void +xfs_extent_busy_reuse( + struct xfs_mount *mp, + xfs_agnumber_t agno, + xfs_agblock_t fbno, + xfs_extlen_t flen, + bool userdata) +{ + struct xfs_perag *pag; + struct rb_node *rbp; + + ASSERT(flen > 0); + + pag = xfs_perag_get(mp, agno); + spin_lock(&pag->pagb_lock); +restart: + rbp = pag->pagb_tree.rb_node; + while (rbp) { + struct xfs_extent_busy *busyp = + rb_entry(rbp, struct xfs_extent_busy, rb_node); + xfs_agblock_t bbno = busyp->bno; + xfs_agblock_t bend = bbno + busyp->length; + + if (fbno + flen <= bbno) { + rbp = rbp->rb_left; + continue; + } else if (fbno >= bend) { + rbp = rbp->rb_right; + continue; + } + + if (!xfs_extent_busy_update_extent(mp, pag, busyp, fbno, flen, + userdata)) + goto restart; + } + spin_unlock(&pag->pagb_lock); + xfs_perag_put(pag); +} + +/* + * For a given extent [fbno, flen], search the busy extent list to find a + * subset of the extent that is not busy. If *rlen is smaller than + * args->minlen no suitable extent could be found, and the higher level + * code needs to force out the log and retry the allocation. + */ +void +xfs_extent_busy_trim( + struct xfs_alloc_arg *args, + xfs_agblock_t bno, + xfs_extlen_t len, + xfs_agblock_t *rbno, + xfs_extlen_t *rlen) +{ + xfs_agblock_t fbno; + xfs_extlen_t flen; + struct rb_node *rbp; + + ASSERT(len > 0); + + spin_lock(&args->pag->pagb_lock); +restart: + fbno = bno; + flen = len; + rbp = args->pag->pagb_tree.rb_node; + while (rbp && flen >= args->minlen) { + struct xfs_extent_busy *busyp = + rb_entry(rbp, struct xfs_extent_busy, rb_node); + xfs_agblock_t fend = fbno + flen; + xfs_agblock_t bbno = busyp->bno; + xfs_agblock_t bend = bbno + busyp->length; + + if (fend <= bbno) { + rbp = rbp->rb_left; + continue; + } else if (fbno >= bend) { + rbp = rbp->rb_right; + continue; + } + + /* + * If this is a metadata allocation, try to reuse the busy + * extent instead of trimming the allocation. + */ + if (!args->userdata && + !(busyp->flags & XFS_EXTENT_BUSY_DISCARDED)) { + if (!xfs_extent_busy_update_extent(args->mp, args->pag, + busyp, fbno, flen, + false)) + goto restart; + continue; + } + + if (bbno <= fbno) { + /* start overlap */ + + /* + * Case 1: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +---------+ + * fbno fend + * + * Case 2: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-------------+ + * fbno fend + * + * Case 3: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-------------+ + * fbno fend + * + * Case 4: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------+ + * fbno fend + * + * No unbusy region in extent, return failure. + */ + if (fend <= bend) + goto fail; + + /* + * Case 5: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +----------------------+ + * fbno fend + * + * Case 6: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Needs to be trimmed to: + * +-------+ + * fbno fend + */ + fbno = bend; + } else if (bend >= fend) { + /* end overlap */ + + /* + * Case 7: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +------------------+ + * fbno fend + * + * Case 8: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Needs to be trimmed to: + * +-------+ + * fbno fend + */ + fend = bbno; + } else { + /* middle overlap */ + + /* + * Case 9: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------------------------+ + * fbno fend + * + * Can be trimmed to: + * +-------+ OR +-------+ + * fbno fend fbno fend + * + * Backward allocation leads to significant + * fragmentation of directories, which degrades + * directory performance, therefore we always want to + * choose the option that produces forward allocation + * patterns. + * Preferring the lower bno extent will make the next + * request use "fend" as the start of the next + * allocation; if the segment is no longer busy at + * that point, we'll get a contiguous allocation, but + * even if it is still busy, we will get a forward + * allocation. + * We try to avoid choosing the segment at "bend", + * because that can lead to the next allocation + * taking the segment at "fbno", which would be a + * backward allocation. We only use the segment at + * "fbno" if it is much larger than the current + * requested size, because in that case there's a + * good chance subsequent allocations will be + * contiguous. + */ + if (bbno - fbno >= args->maxlen) { + /* left candidate fits perfect */ + fend = bbno; + } else if (fend - bend >= args->maxlen * 4) { + /* right candidate has enough free space */ + fbno = bend; + } else if (bbno - fbno >= args->minlen) { + /* left candidate fits minimum requirement */ + fend = bbno; + } else { + goto fail; + } + } + + flen = fend - fbno; + } + spin_unlock(&args->pag->pagb_lock); + + if (fbno != bno || flen != len) { + trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len, + fbno, flen); + } + *rbno = fbno; + *rlen = flen; + return; +fail: + /* + * Return a zero extent length as failure indications. All callers + * re-check if the trimmed extent satisfies the minlen requirement. + */ + 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; +} -- cgit v1.2.3-54-g00ecf