Provide functions to adjust the reference counts for an extent of
physical blocks stored in the refcount btree.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/libxfs/xfs_refcount.c | 803 ++++++++++++++++++++++++++++++++++++++++++
fs/xfs/libxfs/xfs_refcount.h | 8
2 files changed, 811 insertions(+)
diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c
index b3f2c25..dae6453 100644
--- a/fs/xfs/libxfs/xfs_refcount.c
+++ b/fs/xfs/libxfs/xfs_refcount.c
@@ -167,3 +167,806 @@ xfs_refcountbt_delete(
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);
+}
diff --git a/fs/xfs/libxfs/xfs_refcount.h b/fs/xfs/libxfs/xfs_refcount.h
index 033a9b1..6640e3d 100644
--- a/fs/xfs/libxfs/xfs_refcount.h
+++ b/fs/xfs/libxfs/xfs_refcount.h
@@ -26,4 +26,12 @@ extern int xfs_refcountbt_lookup_ge(struct xfs_btree_cur
*cur,
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);
+
#endif /* __XFS_REFCOUNT_H__ */
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