Provide functions to adjust the reference counts for an extent of
physical blocks stored in the refcount btree.
v2: Refactor the left/right split code into a single function. Track
the number of btree shape changes and record updates during a refcount
update so that we can decide if we need to get a fresh transaction to
continue.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
include/xfs_trace.h | 20 +
libxfs/xfs_refcount.c | 783 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 803 insertions(+)
diff --git a/include/xfs_trace.h b/include/xfs_trace.h
index 937d5f5..5605c3c 100644
--- a/include/xfs_trace.h
+++ b/include/xfs_trace.h
@@ -235,6 +235,26 @@
#define trace_xfs_refcountbt_free_block(...) ((void) 0)
#define trace_xfs_refcountbt_alloc_block(...) ((void) 0)
#define trace_xfs_refcount_rec_order_error(...) ((void) 0)
+#define trace_xfs_refcount_split_extent(...) ((void) 0)
+#define trace_xfs_refcount_split_extent_error(...) ((void) 0)
+#define trace_xfs_refcount_merge_center_extents_error(...) ((void) 0)
+#define trace_xfs_refcount_merge_left_extent_error(...) ((void) 0)
+#define trace_xfs_refcount_merge_right_extent_error(...) ((void) 0)
+#define trace_xfs_refcount_find_left_extent(...) ((void) 0)
+#define trace_xfs_refcount_find_left_extent_error(...) ((void) 0)
+#define trace_xfs_refcount_find_right_extent(...) ((void) 0)
+#define trace_xfs_refcount_find_right_extent_error(...) ((void) 0)
+#define trace_xfs_refcount_merge_center_extents(...) ((void) 0)
+#define trace_xfs_refcount_merge_left_extent(...) ((void) 0)
+#define trace_xfs_refcount_merge_right_extent(...) ((void) 0)
+#define trace_xfs_refcount_modify_extent(...) ((void) 0)
+#define trace_xfs_refcount_modify_extent_error(...) ((void) 0)
+#define trace_xfs_refcount_adjust_error(...) ((void) 0)
+#define trace_xfs_refcount_increase(...) ((void) 0)
+#define trace_xfs_refcount_decrease(...) ((void) 0)
+#define trace_xfs_refcount_deferred(...) ((void) 0)
+#define trace_xfs_refcount_defer(...) ((void) 0)
+#define trace_xfs_refcount_finish_one_leftover(...) ((void) 0)
/* set c = c to avoid unused var warnings */
#define trace_xfs_perag_get(a,b,c,d) ((c) = (c))
diff --git a/libxfs/xfs_refcount.c b/libxfs/xfs_refcount.c
index 8b522e2..08866f8 100644
--- a/libxfs/xfs_refcount.c
+++ b/libxfs/xfs_refcount.c
@@ -36,6 +36,12 @@
#include "xfs_bit.h"
#include "xfs_refcount.h"
+/* Allowable refcount adjustment amounts. */
+enum xfs_refc_adjust_op {
+ XFS_REFCOUNT_ADJUST_INCREASE = 1,
+ XFS_REFCOUNT_ADJUST_DECREASE = -1,
+};
+
/*
* Look up the first record less than or equal to [bno, len] in the btree
* given by cur.
@@ -174,3 +180,780 @@ out_error:
cur->bc_private.a.agno, error, _RET_IP_);
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 refcount extent that crosses agbno.
+ */
+STATIC int
+xfs_refcount_split_extent(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t agbno,
+ bool *shape_changed)
+{
+ struct xfs_refcount_irec rcext, tmp;
+ int found_rec;
+ int error;
+
+ *shape_changed = false;
+ error = xfs_refcount_lookup_le(cur, agbno, &found_rec);
+ if (error)
+ goto out_error;
+ if (!found_rec)
+ return 0;
+
+ error = xfs_refcount_get_rec(cur, &rcext, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1, out_error);
+ if (rcext.rc_startblock == agbno || RCNEXT(rcext) <= agbno)
+ return 0;
+
+ *shape_changed = true;
+ trace_xfs_refcount_split_extent(cur->bc_mp, cur->bc_private.a.agno,
+ &rcext, agbno);
+
+ /* Establish the right extent. */
+ tmp = rcext;
+ tmp.rc_startblock = agbno;
+ tmp.rc_blockcount -= (agbno - rcext.rc_startblock);
+ error = xfs_refcount_update(cur, &tmp);
+ if (error)
+ goto out_error;
+
+ /* Insert the left extent. */
+ tmp = rcext;
+ tmp.rc_blockcount = agbno - rcext.rc_startblock;
+ error = xfs_refcount_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_extent_error(cur->bc_mp,
+ cur->bc_private.a.agno, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Merge the left, center, and right extents.
+ */
+STATIC int
+xfs_refcount_merge_center_extent(
+ 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_refcount_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_refcount_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_refcount_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+ }
+
+ error = xfs_refcount_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_refcount_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
+xfs_refcount_merge_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)
+{
+ int error;
+ int found_rec;
+
+ if (cleft->rc_refcount > 1) {
+ error = xfs_refcount_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_refcount_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+ }
+
+ error = xfs_refcount_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_refcount_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
+xfs_refcount_merge_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)
+{
+ int error;
+ int found_rec;
+
+ if (cright->rc_refcount > 1) {
+ error = xfs_refcount_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_refcount_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp, found_rec == 1,
+ out_error);
+ }
+
+ error = xfs_refcount_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_refcount_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
+xfs_refcount_find_left_extents(
+ 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_refcount_lookup_le(cur, agbno - 1, &found_rec);
+ if (error)
+ goto out_error;
+ if (!found_rec)
+ return 0;
+
+ error = xfs_refcount_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_refcount_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
+xfs_refcount_find_right_extents(
+ 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_refcount_lookup_ge(cur, agbno + aglen, &found_rec);
+ if (error)
+ goto out_error;
+ if (!found_rec)
+ return 0;
+
+ error = xfs_refcount_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_refcount_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
+xfs_refcount_merge_extents(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t *agbno,
+ xfs_extlen_t *aglen,
+ enum xfs_refc_adjust_op adjust,
+ bool *shape_changed)
+{
+ struct xfs_refcount_irec left = {0}, cleft = {0};
+ struct xfs_refcount_irec cright = {0}, right = {0};
+ int error;
+ unsigned long long ulen;
+ bool cequal;
+
+ *shape_changed = false;
+ /*
+ * Find the extent just below agbno [left], just above agbno [cleft],
+ * just below (agbno + aglen) [cright], and just above (agbno + aglen)
+ * [right].
+ */
+ error = xfs_refcount_find_left_extents(cur, &left, &cleft, *agbno,
+ *aglen);
+ if (error)
+ return error;
+ error = xfs_refcount_find_right_extents(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;
+
+ *shape_changed = true;
+ 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 xfs_refcount_merge_center_extent(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 = xfs_refcount_merge_left_extent(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 xfs_refcount_merge_right_extent(cur, &right, &cright,
+ agbno, aglen);
+ }
+
+ return error;
+}
+
+/*
+ * While we're adjusting the refcounts records of an extent, we have
+ * to keep an eye on the number of extents we're dirtying -- run too
+ * many in a single transaction and we'll exceed the transaction's
+ * reservation and crash the fs. Each record adds 12 bytes to the
+ * log (plus any key updates) so we'll conservatively assume 24 bytes
+ * per record. We must also leave space for btree splits on both ends
+ * of the range and space for the CUD and a new CUI.
+ *
+ * XXX: This is a pretty hand-wavy estimate. The penalty for guessing
+ * true incorrectly is a shutdown FS; the penalty for guessing false
+ * incorrectly is more transaction rolls than might be necessary.
+ * Be conservative here.
+ */
+static bool
+xfs_refcount_still_have_space(
+ struct xfs_btree_cur *cur)
+{
+ unsigned long overhead;
+
+ overhead = cur->bc_private.a.priv.refc.shape_changes *
+ xfs_allocfree_log_count(cur->bc_mp, 1);
+ overhead *= cur->bc_mp->m_sb.sb_blocksize;
+
+ /*
+ * Only allow 2 refcount extent updates per transaction if the
+ * refcount continue update "error" has been injected.
+ */
+ if (cur->bc_private.a.priv.refc.nr_ops > 2 &&
+ XFS_TEST_ERROR(false, cur->bc_mp,
+ XFS_ERRTAG_REFCOUNT_CONTINUE_UPDATE,
+ XFS_RANDOM_REFCOUNT_CONTINUE_UPDATE))
+ return false;
+
+ if (cur->bc_private.a.priv.refc.nr_ops == 0)
+ return true;
+ else if (overhead > cur->bc_tp->t_log_res)
+ return false;
+ return cur->bc_tp->t_log_res - overhead >
+ cur->bc_private.a.priv.refc.nr_ops * 32;
+}
+
+/*
+ * 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
+xfs_refcount_adjust_extents(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen,
+ xfs_extlen_t *adjusted,
+ enum xfs_refc_adjust_op adj,
+ struct xfs_defer_ops *dfops,
+ struct xfs_owner_info *oinfo)
+{
+ struct xfs_refcount_irec ext, tmp;
+ int error;
+ int found_rec, found_tmp;
+ xfs_fsblock_t fsbno;
+
+ /* Merging did all the work already. */
+ if (aglen == 0)
+ return 0;
+
+ error = xfs_refcount_lookup_ge(cur, agbno, &found_rec);
+ if (error)
+ goto out_error;
+
+ while (aglen > 0 && xfs_refcount_still_have_space(cur)) {
+ error = xfs_refcount_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_refcount_insert(cur, &tmp,
+ &found_tmp);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
+ found_tmp == 1, out_error);
+ cur->bc_private.a.priv.refc.nr_ops++;
+ } else {
+ fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
+ cur->bc_private.a.agno,
+ tmp.rc_startblock);
+ xfs_bmap_add_free(cur->bc_mp, dfops, fsbno,
+ tmp.rc_blockcount, oinfo);
+ }
+
+ (*adjusted) += tmp.rc_blockcount;
+ agbno += tmp.rc_blockcount;
+ aglen -= tmp.rc_blockcount;
+
+ error = xfs_refcount_lookup_ge(cur, agbno,
+ &found_rec);
+ if (error)
+ goto out_error;
+ }
+
+ /* Stop if there's nothing left to modify */
+ if (aglen == 0 || !xfs_refcount_still_have_space(cur))
+ break;
+
+ /*
+ * Adjust the reference count and either update the tree
+ * (incr) or free the blocks (decr).
+ */
+ if (ext.rc_refcount == MAXREFCOUNT)
+ goto skip;
+ 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_refcount_update(cur, &ext);
+ if (error)
+ goto out_error;
+ cur->bc_private.a.priv.refc.nr_ops++;
+ } else if (ext.rc_refcount == 1) {
+ error = xfs_refcount_delete(cur, &found_rec);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(cur->bc_mp,
+ found_rec == 1, out_error);
+ cur->bc_private.a.priv.refc.nr_ops++;
+ 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, dfops, fsbno,
+ ext.rc_blockcount, oinfo);
+ }
+
+skip:
+ error = xfs_btree_increment(cur, 0, &found_rec);
+ if (error)
+ goto out_error;
+
+advloop:
+ (*adjusted) += ext.rc_blockcount;
+ 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. */
+STATIC int
+xfs_refcount_adjust(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen,
+ xfs_extlen_t *adjusted,
+ enum xfs_refc_adjust_op adj,
+ struct xfs_defer_ops *dfops,
+ struct xfs_owner_info *oinfo)
+{
+ xfs_extlen_t orig_aglen;
+ bool shape_changed;
+ int shape_changes = 0;
+ int error;
+
+ *adjusted = 0;
+ switch (adj) {
+ case XFS_REFCOUNT_ADJUST_INCREASE:
+ trace_xfs_refcount_increase(cur->bc_mp, cur->bc_private.a.agno,
+ agbno, aglen);
+ break;
+ case XFS_REFCOUNT_ADJUST_DECREASE:
+ trace_xfs_refcount_decrease(cur->bc_mp, cur->bc_private.a.agno,
+ agbno, aglen);
+ break;
+ default:
+ ASSERT(0);
+ }
+
+ /*
+ * Ensure that no rcextents cross the boundary of the adjustment range.
+ */
+ error = xfs_refcount_split_extent(cur, agbno, &shape_changed);
+ if (error)
+ goto out_error;
+ if (shape_changed)
+ shape_changes++;
+
+ error = xfs_refcount_split_extent(cur, agbno + aglen, &shape_changed);
+ if (error)
+ goto out_error;
+ if (shape_changed)
+ shape_changes++;
+
+ /*
+ * Try to merge with the left or right extents of the range.
+ */
+ orig_aglen = aglen;
+ error = xfs_refcount_merge_extents(cur, &agbno, &aglen, adj,
+ &shape_changed);
+ if (error)
+ goto out_error;
+ if (shape_changed)
+ shape_changes++;
+ (*adjusted) += orig_aglen - aglen;
+ if (shape_changes)
+ cur->bc_private.a.priv.refc.shape_changes++;
+
+ /* Now that we've taken care of the ends, adjust the middle extents */
+ error = xfs_refcount_adjust_extents(cur, agbno, aglen, adjusted, adj,
+ dfops, oinfo);
+ if (error)
+ goto out_error;
+
+ return 0;
+
+out_error:
+ trace_xfs_refcount_adjust_error(cur->bc_mp, cur->bc_private.a.agno,
+ error, _RET_IP_);
+ return error;
+}
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