Import definitions and refcount helper code from the kernel.
This is a separate patch to avoid blowing out the mail server...
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
libxfs/xfs_refcount.c | 1131 +++++++++++++++++++++++++++++++++++++++++++++++++
libxfs/xfs_refcount.h | 45 ++
2 files changed, 1176 insertions(+)
create mode 100644 libxfs/xfs_refcount.c
create mode 100644 libxfs/xfs_refcount.h
diff --git a/libxfs/xfs_refcount.c b/libxfs/xfs_refcount.c
new file mode 100644
index 0000000..59ec846
--- /dev/null
+++ b/libxfs/xfs_refcount.c
@@ -0,0 +1,1131 @@
+/*
+ * Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
+ * Copyright (c) 2015 Oracle.
+ * 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 "libxfs_priv.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_btree.h"
+#include "xfs_bmap.h"
+#include "xfs_refcount_btree.h"
+#include "xfs_alloc.h"
+#include "xfs_trace.h"
+#include "xfs_cksum.h"
+#include "xfs_trans.h"
+#include "xfs_bit.h"
+#include "xfs_refcount.h"
+
+/**
+ * xfs_refcountbt_lookup_le() -- Look up the first record less than or equal to
+ * [bno, len] in the btree given by cur.
+ * @cur: refcount btree cursor
+ * @bno: AG block number to look up
+ * @stat: set to 1 if successful, 0 otherwise
+ */
+int
+xfs_refcountbt_lookup_le(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t bno,
+ int *stat)
+{
+ trace_xfs_refcountbt_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
+ XFS_LOOKUP_LE);
+ cur->bc_rec.rc.rc_startblock = bno;
+ cur->bc_rec.rc.rc_blockcount = 0;
+ return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
+}
+
+/**
+ * xfs_refcountbt_lookup_ge() -- Look up the first record greater than or equal
+ * to [bno, len] in the btree given by cur.
+ * @cur: refcount btree cursor
+ * @bno: AG block number to look up
+ * @stat: set to 1 if successful, 0 otherwise
+ */
+int /* error */
+xfs_refcountbt_lookup_ge(
+ struct xfs_btree_cur *cur, /* btree cursor */
+ xfs_agblock_t bno, /* starting block of extent */
+ int *stat) /* success/failure */
+{
+ trace_xfs_refcountbt_lookup(cur->bc_mp, cur->bc_private.a.agno, bno,
+ XFS_LOOKUP_GE);
+ cur->bc_rec.rc.rc_startblock = bno;
+ cur->bc_rec.rc.rc_blockcount = 0;
+ return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
+}
+
+/**
+ * xfs_refcountbt_get_rec() -- Get the data from the pointed-to record.
+ *
+ * @cur: refcount btree cursor
+ * @irec: set to the record currently pointed to by the btree cursor
+ * @stat: set to 1 if successful, 0 otherwise
+ */
+int
+xfs_refcountbt_get_rec(
+ struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *irec,
+ int *stat)
+{
+ union xfs_btree_rec *rec;
+ int error;
+
+ error = xfs_btree_get_rec(cur, &rec, stat);
+ if (!error && *stat == 1) {
+ irec->rc_startblock = be32_to_cpu(rec->refc.rc_startblock);
+ irec->rc_blockcount = be32_to_cpu(rec->refc.rc_blockcount);
+ irec->rc_refcount = be32_to_cpu(rec->refc.rc_refcount);
+ trace_xfs_refcountbt_get(cur->bc_mp, cur->bc_private.a.agno,
+ irec);
+ }
+ return error;
+}
+
+/*
+ * Update the record referred to by cur to the value given
+ * by [bno, len, refcount].
+ * This either works (return 0) or gets an EFSCORRUPTED error.
+ */
+STATIC int
+xfs_refcountbt_update(
+ struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *irec)
+{
+ union xfs_btree_rec rec;
+
+ trace_xfs_refcountbt_update(cur->bc_mp, cur->bc_private.a.agno, irec);
+ rec.refc.rc_startblock = cpu_to_be32(irec->rc_startblock);
+ rec.refc.rc_blockcount = cpu_to_be32(irec->rc_blockcount);
+ rec.refc.rc_refcount = cpu_to_be32(irec->rc_refcount);
+ return xfs_btree_update(cur, &rec);
+}
+
+/*
+ * Insert the record referred to by cur to the value given
+ * by [bno, len, refcount].
+ * This either works (return 0) or gets an EFSCORRUPTED error.
+ */
+STATIC int
+xfs_refcountbt_insert(
+ struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *irec,
+ int *i)
+{
+ trace_xfs_refcountbt_insert(cur->bc_mp, cur->bc_private.a.agno, irec);
+ cur->bc_rec.rc.rc_startblock = irec->rc_startblock;
+ cur->bc_rec.rc.rc_blockcount = irec->rc_blockcount;
+ cur->bc_rec.rc.rc_refcount = irec->rc_refcount;
+ return xfs_btree_insert(cur, i);
+}
+
+/*
+ * Remove the record referred to by cur, then set the pointer to the spot
+ * where the record could be re-inserted, in case we want to increment or
+ * decrement the cursor.
+ * This either works (return 0) or gets an EFSCORRUPTED error.
+ */
+STATIC int
+xfs_refcountbt_delete(
+ struct xfs_btree_cur *cur,
+ int *i)
+{
+ struct xfs_refcount_irec irec;
+ int found_rec;
+ int error;
+
+ error = xfs_refcountbt_get_rec(cur, &irec, &found_rec);
+ if (error)
+ return error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+ trace_xfs_refcountbt_delete(cur->bc_mp, cur->bc_private.a.agno, &irec);
+ error = xfs_btree_delete(cur, i);
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, *i == 1, out_error);
+ if (error)
+ return error;
+ error = xfs_refcountbt_lookup_ge(cur, irec.rc_startblock, &found_rec);
+out_error:
+ return error;
+}
+
+/*
+ * Adjusting the Reference Count
+ *
+ * As stated elsewhere, the reference count btree (refcbt) stores
+ * >1 reference counts for extents of physical blocks. In this
+ * operation, we're either raising or lowering the reference count of
+ * some subrange stored in the tree:
+ *
+ * <------ adjustment range ------>
+ * ----+ +---+-----+ +--+--------+---------
+ * 2 | | 3 | 4 | |17| 55 | 10
+ * ----+ +---+-----+ +--+--------+---------
+ * X axis is physical blocks number;
+ * reference counts are the numbers inside the rectangles
+ *
+ * The first thing we need to do is to ensure that there are no
+ * refcount extents crossing either boundary of the range to be
+ * adjusted. For any extent that does cross a boundary, split it into
+ * two extents so that we can increment the refcount of one of the
+ * pieces later:
+ *
+ * <------ adjustment range ------>
+ * ----+ +---+-----+ +--+--------+----+----
+ * 2 | | 3 | 2 | |17| 55 | 10 | 10
+ * ----+ +---+-----+ +--+--------+----+----
+ *
+ * For this next step, let's assume that all the physical blocks in
+ * the adjustment range are mapped to a file and are therefore in use
+ * at least once. Therefore, we can infer that any gap in the
+ * refcount tree within the adjustment range represents a physical
+ * extent with refcount == 1:
+ *
+ * <------ adjustment range ------>
+ * ----+---+---+-----+-+--+--------+----+----
+ * 2 |"1"| 3 | 2 |1|17| 55 | 10 | 10
+ * ----+---+---+-----+-+--+--------+----+----
+ * ^
+ *
+ * For each extent that falls within the interval range, figure out
+ * which extent is to the left or the right of that extent. Now we
+ * have a left, current, and right extent. If the new reference count
+ * of the center extent enables us to merge left, center, and right
+ * into one record covering all three, do so. If the center extent is
+ * at the left end of the range, abuts the left extent, and its new
+ * reference count matches the left extent's record, then merge them.
+ * If the center extent is at the right end of the range, abuts the
+ * right extent, and the reference counts match, merge those. In the
+ * example, we can left merge (assuming an increment operation):
+ *
+ * <------ adjustment range ------>
+ * --------+---+-----+-+--+--------+----+----
+ * 2 | 3 | 2 |1|17| 55 | 10 | 10
+ * --------+---+-----+-+--+--------+----+----
+ * ^
+ *
+ * For all other extents within the range, adjust the reference count
+ * or delete it if the refcount falls below 2. If we were
+ * incrementing, the end result looks like this:
+ *
+ * <------ adjustment range ------>
+ * --------+---+-----+-+--+--------+----+----
+ * 2 | 4 | 3 |2|18| 56 | 11 | 10
+ * --------+---+-----+-+--+--------+----+----
+ *
+ * The result of a decrement operation looks as such:
+ *
+ * <------ adjustment range ------>
+ * ----+ +---+ +--+--------+----+----
+ * 2 | | 2 | |16| 54 | 9 | 10
+ * ----+ +---+ +--+--------+----+----
+ * DDDD 111111DD
+ *
+ * The blocks marked "D" are freed; the blocks marked "1" are only
+ * referenced once and therefore the record is removed from the
+ * refcount btree.
+ */
+
+#define RCNEXT(rc) ((rc).rc_startblock + (rc).rc_blockcount)
+/*
+ * Split a left rcextent that crosses agbno.
+ */
+STATIC int
+try_split_left_rcextent(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t agbno)
+{
+ struct xfs_refcount_irec left, tmp;
+ int found_rec;
+ int error;
+
+ error = xfs_refcountbt_lookup_le(cur, agbno, &found_rec);
+ if (error)
+ goto out_error;
+ if (!found_rec)
+ return 0;
+
+ error = xfs_refcountbt_get_rec(cur, &left, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+ if (left.rc_startblock >= agbno || RCNEXT(left) <= agbno)
+ return 0;
+
+ trace_xfs_refcount_split_left_extent(cur->bc_mp, cur->bc_private.a.agno,
+ &left, agbno);
+ tmp = left;
+ tmp.rc_blockcount = agbno - left.rc_startblock;
+ error = xfs_refcountbt_update(cur, &tmp);
+ if (error)
+ goto out_error;
+
+ error = xfs_btree_increment(cur, 0, &found_rec);
+ if (error)
+ goto out_error;
+
+ tmp = left;
+ tmp.rc_startblock = agbno;
+ tmp.rc_blockcount -= (agbno - left.rc_startblock);
+ error = xfs_refcountbt_insert(cur, &tmp, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+ return error;
+
+out_error:
+ trace_xfs_refcount_split_left_extent_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Split a right rcextent that crosses agbno.
+ */
+STATIC int
+try_split_right_rcextent(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t agbnext)
+{
+ struct xfs_refcount_irec right, tmp;
+ int found_rec;
+ int error;
+
+ error = xfs_refcountbt_lookup_le(cur, agbnext - 1, &found_rec);
+ if (error)
+ goto out_error;
+ if (!found_rec)
+ return 0;
+
+ error = xfs_refcountbt_get_rec(cur, &right, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+ if (RCNEXT(right) <= agbnext)
+ return 0;
+
+ trace_xfs_refcount_split_right_extent(cur->bc_mp,
+ cur->bc_private.a.agno, &right, agbnext);
+ tmp = right;
+ tmp.rc_startblock = agbnext;
+ tmp.rc_blockcount -= (agbnext - right.rc_startblock);
+ error = xfs_refcountbt_update(cur, &tmp);
+ if (error)
+ goto out_error;
+
+ tmp = right;
+ tmp.rc_blockcount = agbnext - right.rc_startblock;
+ error = xfs_refcountbt_insert(cur, &tmp, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+ return error;
+
+out_error:
+ trace_xfs_refcount_split_right_extent_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Merge the left, center, and right extents.
+ */
+STATIC int
+merge_center(
+ struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *left,
+ struct xfs_refcount_irec *center,
+ unsigned long long extlen,
+ xfs_agblock_t *agbno,
+ xfs_extlen_t *aglen)
+{
+ int error;
+ int found_rec;
+
+ error = xfs_refcountbt_lookup_ge(cur, center->rc_startblock,
+ &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+
+ error = xfs_refcountbt_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+
+ if (center->rc_refcount > 1) {
+ error = xfs_refcountbt_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+ }
+
+ error = xfs_refcountbt_lookup_le(cur, left->rc_startblock,
+ &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+
+ left->rc_blockcount = extlen;
+ error = xfs_refcountbt_update(cur, left);
+ if (error)
+ goto out_error;
+
+ *aglen = 0;
+ return error;
+
+out_error:
+ trace_xfs_refcount_merge_center_extents_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Merge with the left extent.
+ */
+STATIC int
+merge_left(
+ struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *left,
+ struct xfs_refcount_irec *cleft,
+ xfs_agblock_t *agbno,
+ xfs_extlen_t *aglen)
+{
+ int error;
+ int found_rec;
+
+ if (cleft->rc_refcount > 1) {
+ error = xfs_refcountbt_lookup_le(cur, cleft->rc_startblock,
+ &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+
+ error = xfs_refcountbt_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+ }
+
+ error = xfs_refcountbt_lookup_le(cur, left->rc_startblock,
+ &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+
+ left->rc_blockcount += cleft->rc_blockcount;
+ error = xfs_refcountbt_update(cur, left);
+ if (error)
+ goto out_error;
+
+ *agbno += cleft->rc_blockcount;
+ *aglen -= cleft->rc_blockcount;
+ return error;
+
+out_error:
+ trace_xfs_refcount_merge_left_extent_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Merge with the right extent.
+ */
+STATIC int
+merge_right(
+ struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *right,
+ struct xfs_refcount_irec *cright,
+ xfs_agblock_t *agbno,
+ xfs_extlen_t *aglen)
+{
+ int error;
+ int found_rec;
+
+ if (cright->rc_refcount > 1) {
+ error = xfs_refcountbt_lookup_le(cur, cright->rc_startblock,
+ &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+
+ error = xfs_refcountbt_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+ }
+
+ error = xfs_refcountbt_lookup_le(cur, right->rc_startblock,
+ &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+
+ right->rc_startblock -= cright->rc_blockcount;
+ right->rc_blockcount += cright->rc_blockcount;
+ error = xfs_refcountbt_update(cur, right);
+ if (error)
+ goto out_error;
+
+ *aglen -= cright->rc_blockcount;
+ return error;
+
+out_error:
+ trace_xfs_refcount_merge_right_extent_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Find the left extent and the one after it (cleft). This function assumes
+ * that we've already split any extent crossing agbno.
+ */
+STATIC int
+find_left_extent(
+ struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *left,
+ struct xfs_refcount_irec *cleft,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen)
+{
+ struct xfs_refcount_irec tmp;
+ int error;
+ int found_rec;
+
+ left->rc_blockcount = cleft->rc_blockcount = 0;
+ error = xfs_refcountbt_lookup_le(cur, agbno - 1, &found_rec);
+ if (error)
+ goto out_error;
+ if (!found_rec)
+ return 0;
+
+ error = xfs_refcountbt_get_rec(cur, &tmp, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+
+ if (RCNEXT(tmp) != agbno)
+ return 0;
+ /* We have a left extent; retrieve (or invent) the next right one */
+ *left = tmp;
+
+ error = xfs_btree_increment(cur, 0, &found_rec);
+ if (error)
+ goto out_error;
+ if (found_rec) {
+ error = xfs_refcountbt_get_rec(cur, &tmp, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+
+ /* if tmp starts at the end of our range, just use that */
+ if (tmp.rc_startblock == agbno)
+ *cleft = tmp;
+ else {
+ /*
+ * There's a gap in the refcntbt at the start of the
+ * range we're interested in (refcount == 1) so
+ * create the implied extent and pass it back.
+ */
+ cleft->rc_startblock = agbno;
+ cleft->rc_blockcount = min(aglen,
+ tmp.rc_startblock - agbno);
+ cleft->rc_refcount = 1;
+ }
+ } else {
+ /*
+ * No extents, so pretend that there's one covering the whole
+ * range.
+ */
+ cleft->rc_startblock = agbno;
+ cleft->rc_blockcount = aglen;
+ cleft->rc_refcount = 1;
+ }
+ trace_xfs_refcount_find_left_extent(cur->bc_mp, cur->bc_private.a.agno,
+ left, cleft, agbno);
+ return error;
+
+out_error:
+ trace_xfs_refcount_find_left_extent_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Find the right extent and the one before it (cright). This function
+ * assumes that we've already split any extents crossing agbno + aglen.
+ */
+STATIC int
+find_right_extent(
+ struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *right,
+ struct xfs_refcount_irec *cright,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen)
+{
+ struct xfs_refcount_irec tmp;
+ int error;
+ int found_rec;
+
+ right->rc_blockcount = cright->rc_blockcount = 0;
+ error = xfs_refcountbt_lookup_ge(cur, agbno + aglen, &found_rec);
+ if (error)
+ goto out_error;
+ if (!found_rec)
+ return 0;
+
+ error = xfs_refcountbt_get_rec(cur, &tmp, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+
+ if (tmp.rc_startblock != agbno + aglen)
+ return 0;
+ /* We have a right extent; retrieve (or invent) the next left one */
+ *right = tmp;
+
+ error = xfs_btree_decrement(cur, 0, &found_rec);
+ if (error)
+ goto out_error;
+ if (found_rec) {
+ error = xfs_refcountbt_get_rec(cur, &tmp, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+
+ /* if tmp ends at the end of our range, just use that */
+ if (RCNEXT(tmp) == agbno + aglen)
+ *cright = tmp;
+ else {
+ /*
+ * There's a gap in the refcntbt at the end of the
+ * range we're interested in (refcount == 1) so
+ * create the implied extent and pass it back.
+ */
+ cright->rc_startblock = max(agbno, RCNEXT(tmp));
+ cright->rc_blockcount = right->rc_startblock -
+ cright->rc_startblock;
+ cright->rc_refcount = 1;
+ }
+ } else {
+ /*
+ * No extents, so pretend that there's one covering the whole
+ * range.
+ */
+ cright->rc_startblock = agbno;
+ cright->rc_blockcount = aglen;
+ cright->rc_refcount = 1;
+ }
+ trace_xfs_refcount_find_right_extent(cur->bc_mp, cur->bc_private.a.agno,
+ cright, right, agbno + aglen);
+ return error;
+
+out_error:
+ trace_xfs_refcount_find_right_extent_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+#undef RCNEXT
+
+/*
+ * Try to merge with any extents on the boundaries of the adjustment range.
+ */
+STATIC int
+try_merge_rcextents(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t *agbno,
+ xfs_extlen_t *aglen,
+ int adjust)
+{
+ struct xfs_refcount_irec left = {0}, cleft = {0};
+ struct xfs_refcount_irec cright = {0}, right = {0};
+ int error;
+ unsigned long long ulen;
+ bool cequal;
+
+ /*
+ * Find the extent just below agbno [left], just above agbno [cleft],
+ * just below (agbno + aglen) [cright], and just above (agbno + aglen)
+ * [right].
+ */
+ error = find_left_extent(cur, &left, &cleft, *agbno, *aglen);
+ if (error)
+ return error;
+ error = find_right_extent(cur, &right, &cright, *agbno, *aglen);
+ if (error)
+ return error;
+
+ /* No left or right extent to merge; exit. */
+ if (left.rc_blockcount == 0 && right.rc_blockcount == 0)
+ return 0;
+
+ cequal = (cleft.rc_startblock == cright.rc_startblock) &&
+ (cleft.rc_blockcount == cright.rc_blockcount);
+
+ /* Try to merge left, cleft, and right. cleft must == cright. */
+ ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount +
+ right.rc_blockcount;
+ if (left.rc_blockcount != 0 && right.rc_blockcount != 0 &&
+ cleft.rc_blockcount != 0 && cright.rc_blockcount != 0 &&
+ cequal &&
+ left.rc_refcount == cleft.rc_refcount + adjust &&
+ right.rc_refcount == cleft.rc_refcount + adjust &&
+ ulen < MAXREFCEXTLEN) {
+ trace_xfs_refcount_merge_center_extents(cur->bc_mp,
+ cur->bc_private.a.agno, &left, &cleft, &right);
+ return merge_center(cur, &left, &cleft, ulen, agbno, aglen);
+ }
+
+ /* Try to merge left and cleft. */
+ ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount;
+ if (left.rc_blockcount != 0 && cleft.rc_blockcount != 0 &&
+ left.rc_refcount == cleft.rc_refcount + adjust &&
+ ulen < MAXREFCEXTLEN) {
+ trace_xfs_refcount_merge_left_extent(cur->bc_mp,
+ cur->bc_private.a.agno, &left, &cleft);
+ error = merge_left(cur, &left, &cleft, agbno, aglen);
+ if (error)
+ return error;
+
+ /*
+ * If we just merged left + cleft and cleft == cright,
+ * we no longer have a cright to merge with right. We're done.
+ */
+ if (cequal)
+ return 0;
+ }
+
+ /* Try to merge cright and right. */
+ ulen = (unsigned long long)right.rc_blockcount + cright.rc_blockcount;
+ if (right.rc_blockcount != 0 && cright.rc_blockcount != 0 &&
+ right.rc_refcount == cright.rc_refcount + adjust &&
+ ulen < MAXREFCEXTLEN) {
+ trace_xfs_refcount_merge_right_extent(cur->bc_mp,
+ cur->bc_private.a.agno, &cright, &right);
+ return merge_right(cur, &right, &cright, agbno, aglen);
+ }
+
+ return error;
+}
+
+/*
+ * Adjust the refcounts of middle extents. At this point we should have
+ * split extents that crossed the adjustment range; merged with adjacent
+ * extents; and updated agbno/aglen to reflect the merges. Therefore,
+ * all we have to do is update the extents inside [agbno, agbno + aglen].
+ */
+STATIC int
+adjust_rcextents(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen,
+ int adj,
+ struct xfs_bmap_free *flist,
+ struct xfs_owner_info *oinfo)
+{
+ struct xfs_refcount_irec ext, tmp;
+ int error;
+ int found_rec, found_tmp;
+ xfs_fsblock_t fsbno;
+
+ error = xfs_refcountbt_lookup_ge(cur, agbno, &found_rec);
+ if (error)
+ goto out_error;
+
+ while (aglen > 0) {
+ error = xfs_refcountbt_get_rec(cur, &ext, &found_rec);
+ if (error)
+ goto out_error;
+ if (!found_rec) {
+ ext.rc_startblock = cur->bc_mp->m_sb.sb_agblocks;
+ ext.rc_blockcount = 0;
+ ext.rc_refcount = 0;
+ }
+
+ /*
+ * Deal with a hole in the refcount tree; if a file maps to
+ * these blocks and there's no refcountbt recourd, pretend that
+ * there is one with refcount == 1.
+ */
+ if (ext.rc_startblock != agbno) {
+ tmp.rc_startblock = agbno;
+ tmp.rc_blockcount = min(aglen,
+ ext.rc_startblock - agbno);
+ tmp.rc_refcount = 1 + adj;
+ trace_xfs_refcount_modify_extent(cur->bc_mp,
+ cur->bc_private.a.agno, &tmp);
+
+ /*
+ * Either cover the hole (increment) or
+ * delete the range (decrement).
+ */
+ if (tmp.rc_refcount) {
+ error = xfs_refcountbt_insert(cur, &tmp,
+ &found_tmp);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
+ found_tmp == 1, out_error);
+ } else {
+ fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
+ cur->bc_private.a.agno,
+ tmp.rc_startblock);
+ xfs_bmap_add_free(cur->bc_mp, flist, fsbno,
+ tmp.rc_blockcount, oinfo);
+ }
+
+ agbno += tmp.rc_blockcount;
+ aglen -= tmp.rc_blockcount;
+
+ error = xfs_refcountbt_lookup_ge(cur, agbno,
+ &found_rec);
+ if (error)
+ goto out_error;
+ }
+
+ /* Stop if there's nothing left to modify */
+ if (aglen == 0)
+ break;
+
+ /*
+ * Adjust the reference count and either update the tree
+ * (incr) or free the blocks (decr).
+ */
+ ext.rc_refcount += adj;
+ trace_xfs_refcount_modify_extent(cur->bc_mp,
+ cur->bc_private.a.agno, &ext);
+ if (ext.rc_refcount > 1) {
+ error = xfs_refcountbt_update(cur, &ext);
+ if (error)
+ goto out_error;
+ } else if (ext.rc_refcount == 1) {
+ error = xfs_refcountbt_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
+ found_rec == 1, out_error);
+ goto advloop;
+ } else {
+ fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
+ cur->bc_private.a.agno,
+ ext.rc_startblock);
+ xfs_bmap_add_free(cur->bc_mp, flist, fsbno,
+ ext.rc_blockcount, oinfo);
+ }
+
+ error = xfs_btree_increment(cur, 0, &found_rec);
+ if (error)
+ goto out_error;
+
+advloop:
+ agbno += ext.rc_blockcount;
+ aglen -= ext.rc_blockcount;
+ }
+
+ return error;
+out_error:
+ trace_xfs_refcount_modify_extent_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Adjust the reference count of a range of AG blocks.
+ *
+ * @mp: XFS mount object
+ * @tp: XFS transaction object
+ * @agbp: Buffer containing the AGF
+ * @agno: AG number
+ * @agbno: Start of range to adjust
+ * @aglen: Length of range to adjust
+ * @adj: +1 to increment, -1 to decrement reference count
+ * @flist: freelist (only required if adj == -1)
+ * @owner: owner of the blocks (only required if adj == -1)
+ */
+STATIC int
+xfs_refcountbt_adjust_refcount(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_buf *agbp,
+ xfs_agnumber_t agno,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen,
+ int adj,
+ struct xfs_bmap_free *flist,
+ struct xfs_owner_info *oinfo)
+{
+ struct xfs_btree_cur *cur;
+ int error;
+
+ cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, flist);
+
+ /*
+ * Ensure that no rcextents cross the boundary of the adjustment range.
+ */
+ error = try_split_left_rcextent(cur, agbno);
+ if (error)
+ goto out_error;
+
+ error = try_split_right_rcextent(cur, agbno + aglen);
+ if (error)
+ goto out_error;
+
+ /*
+ * Try to merge with the left or right extents of the range.
+ */
+ error = try_merge_rcextents(cur, &agbno, &aglen, adj);
+ if (error)
+ goto out_error;
+
+ /* Now that we've taken care of the ends, adjust the middle extents */
+ error = adjust_rcextents(cur, agbno, aglen, adj, flist, oinfo);
+ if (error)
+ goto out_error;
+
+ xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+ return 0;
+
+out_error:
+ trace_xfs_refcount_adjust_error(mp, agno, error, _RET_IP_);
+ xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+ return error;
+}
+
+/**
+ * Increase the reference count of a range of AG blocks.
+ *
+ * @mp: XFS mount object
+ * @tp: XFS transaction object
+ * @agbp: Buffer containing the AGF
+ * @agno: AG number
+ * @agbno: Start of range to adjust
+ * @aglen: Length of range to adjust
+ * @flist: List of blocks to free
+ */
+int
+xfs_refcount_increase(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_buf *agbp,
+ xfs_agnumber_t agno,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen,
+ struct xfs_bmap_free *flist)
+{
+ trace_xfs_refcount_increase(mp, agno, agbno, aglen);
+ return xfs_refcountbt_adjust_refcount(mp, tp, agbp, agno, agbno,
+ aglen, 1, flist, NULL);
+}
+
+/**
+ * Decrease the reference count of a range of AG blocks.
+ *
+ * @mp: XFS mount object
+ * @tp: XFS transaction object
+ * @agbp: Buffer containing the AGF
+ * @agno: AG number
+ * @agbno: Start of range to adjust
+ * @aglen: Length of range to adjust
+ * @flist: List of blocks to free
+ * @owner: Extent owner
+ */
+int
+xfs_refcount_decrease(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_buf *agbp,
+ xfs_agnumber_t agno,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen,
+ struct xfs_bmap_free *flist,
+ struct xfs_owner_info *oinfo)
+{
+ trace_xfs_refcount_decrease(mp, agno, agbno, aglen);
+ return xfs_refcountbt_adjust_refcount(mp, tp, agbp, agno, agbno,
+ aglen, -1, flist, oinfo);
+}
+
+/**
+ * xfs_refcount_put_extent() - release a range of blocks
+ *
+ * @mp: XFS mount object
+ * @tp: transaction that goes with the free operation
+ * @flist: List of blocks to be freed at the end of the transaction
+ * @fsbno: First fs block of the range to release
+ * @len: Length of range
+ * @owner: owner of the extent
+ */
+int
+xfs_refcount_put_extent(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_bmap_free *flist,
+ xfs_fsblock_t fsbno,
+ xfs_filblks_t fslen,
+ struct xfs_owner_info *oinfo)
+{
+ int error;
+ struct xfs_buf *agbp;
+ xfs_agnumber_t agno; /* allocation group number */
+ xfs_agblock_t agbno; /* ag start of range to free */
+ xfs_extlen_t aglen; /* ag length of range to free */
+
+ agno = XFS_FSB_TO_AGNO(mp, fsbno);
+ agbno = XFS_FSB_TO_AGBNO(mp, fsbno);
+ aglen = fslen;
+
+ /*
+ * Drop reference counts in the refcount tree.
+ */
+ error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
+ if (error)
+ return error;
+
+ error = xfs_refcount_decrease(mp, tp, agbp, agno, agbno, aglen, flist,
+ oinfo);
+ xfs_trans_brelse(tp, agbp);
+ return error;
+}
+
+/**
+ * xfs_refcount_find_shared() -- Given an AG extent, find the lowest-numbered
+ * run of shared blocks within that range.
+ *
+ * @mp: XFS mount.
+ * @agno: AG number.
+ * @agbno: AG block number to start searching.
+ * @aglen: Length of the range to search.
+ * @fbno: Returns the AG block number of the first shared range, or
+ * agbno + aglen if no shared blocks are found.
+ * @flen: Returns the length of the shared range found, or 0 if no shared
+ * blocks are found.
+ * @find_maximal: If true, find the length of the run of shared blocks.
+ * Otherwise, the length of the first refcount extent is found.
+ */
+int
+xfs_refcount_find_shared(
+ struct xfs_mount *mp,
+ xfs_agnumber_t agno,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen,
+ xfs_agblock_t *fbno,
+ xfs_extlen_t *flen,
+ bool find_maximal)
+{
+ struct xfs_btree_cur *cur;
+ struct xfs_buf *agbp;
+ struct xfs_refcount_irec tmp;
+ int error;
+ int i, have;
+ int bt_error = XFS_BTREE_ERROR;
+
+ trace_xfs_refcount_find_shared(mp, agno, agbno, aglen);
+
+ error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
+ if (error)
+ goto out;
+ cur = xfs_refcountbt_init_cursor(mp, NULL, agbp, agno, NULL);
+
+ /* By default, skip the whole range */
+ *fbno = agbno + aglen;
+ *flen = 0;
+
+ /* Try to find a refcount extent that crosses the start */
+ error = xfs_refcountbt_lookup_le(cur, agbno, &have);
+ if (error)
+ goto out_error;
+ if (!have) {
+ /* No left extent, look at the next one */
+ error = xfs_btree_increment(cur, 0, &have);
+ if (error)
+ goto out_error;
+ if (!have)
+ goto done;
+ }
+ error = xfs_refcountbt_get_rec(cur, &tmp, &i);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+
+ /* If the extent ends before the start, look at the next one */
+ if (tmp.rc_startblock + tmp.rc_blockcount <= agbno) {
+ error = xfs_btree_increment(cur, 0, &have);
+ if (error)
+ goto out_error;
+ if (!have)
+ goto done;
+ error = xfs_refcountbt_get_rec(cur, &tmp, &i);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+ }
+
+ /* If the extent ends after the range we want, bail out */
+ if (tmp.rc_startblock >= agbno + aglen)
+ goto done;
+
+ /* We found the start of a shared extent! */
+ if (tmp.rc_startblock < agbno) {
+ tmp.rc_blockcount -= (agbno - tmp.rc_startblock);
+ tmp.rc_startblock = agbno;
+ }
+
+ *fbno = tmp.rc_startblock;
+ *flen = min(tmp.rc_blockcount, agbno + aglen - *fbno);
+ if (!find_maximal)
+ goto done;
+
+ /* Otherwise, find the end of this shared extent */
+ while (*fbno + *flen < agbno + aglen) {
+ error = xfs_btree_increment(cur, 0, &have);
+ if (error)
+ goto out_error;
+ if (!have)
+ break;
+ error = xfs_refcountbt_get_rec(cur, &tmp, &i);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+ if (tmp.rc_startblock >= agbno + aglen ||
+ tmp.rc_startblock != *fbno + *flen)
+ break;
+ *flen = min(*flen + tmp.rc_blockcount, agbno + aglen - *fbno);
+ }
+
+done:
+ bt_error = XFS_BTREE_NOERROR;
+ trace_xfs_refcount_find_shared_result(mp, agno, *fbno, *flen);
+
+out_error:
+ xfs_btree_del_cursor(cur, bt_error);
+ xfs_buf_relse(agbp);
+out:
+ if (error)
+ trace_xfs_refcount_find_shared_error(mp, agno, error, _RET_IP_);
+ return error;
+}
diff --git a/libxfs/xfs_refcount.h b/libxfs/xfs_refcount.h
new file mode 100644
index 0000000..e8e0beb
--- /dev/null
+++ b/libxfs/xfs_refcount.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2000,2005 Silicon Graphics, Inc.
+ * Copyright (c) 2015 Oracle.
+ * 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
+ */
+#ifndef __XFS_REFCOUNT_H__
+#define __XFS_REFCOUNT_H__
+
+extern int xfs_refcountbt_lookup_le(struct xfs_btree_cur *cur,
+ xfs_agblock_t bno, int *stat);
+extern int xfs_refcountbt_lookup_ge(struct xfs_btree_cur *cur,
+ xfs_agblock_t bno, int *stat);
+extern int xfs_refcountbt_get_rec(struct xfs_btree_cur *cur,
+ struct xfs_refcount_irec *irec, int *stat);
+
+extern int xfs_refcount_increase(struct xfs_mount *mp, struct xfs_trans *tp,
+ struct xfs_buf *agbp, xfs_agnumber_t agno, xfs_agblock_t agbno,
+ xfs_extlen_t aglen, struct xfs_bmap_free *flist);
+extern int xfs_refcount_decrease(struct xfs_mount *mp, struct xfs_trans *tp,
+ struct xfs_buf *agbp, xfs_agnumber_t agno, xfs_agblock_t agbno,
+ xfs_extlen_t aglen, struct xfs_bmap_free *flist,
+ struct xfs_owner_info *oinfo);
+
+extern int xfs_refcount_put_extent(struct xfs_mount *mp, struct xfs_trans *tp,
+ struct xfs_bmap_free *flist, xfs_fsblock_t fsbno,
+ xfs_filblks_t len, struct xfs_owner_info *oinfo);
+
+extern int xfs_refcount_find_shared(struct xfs_mount *mp, xfs_agnumber_t agno,
+ xfs_agblock_t agbno, xfs_extlen_t aglen, xfs_agblock_t *fbno,
+ xfs_extlen_t *flen, bool find_maximal);
+
+#endif /* __XFS_REFCOUNT_H__ */
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