[PATCH 14/16] xfs: remove an extent from the rmap btree

Dave Chinner
2016-03-08T04:17:21Z

From: Dave Chinner <dchinner@redhat.com>

Now that we have records in the rmap btree, we need to remove them
when extents are freed. This needs to find the relevant record in
the btree and remove/trim/split it accordingly.

[darrick.wong@oracle.com: make rmap routines handle the enlarged keyspace]
[dchinner: remove remaining unused debug printks]

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
---
fs/xfs/libxfs/xfs_rmap.c | 158 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 156 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
index 56627c1c..d2e01b2 100644
--- a/fs/xfs/libxfs/xfs_rmap.c
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -118,6 +118,24 @@ xfs_rmap_get_rec(
return 0;
}

+/*
+ * Find the extent in the rmap btree and remove it.
+ *
+ * The record we find should always be an exact match for the extent that we're
+ * looking for, since we insert them into the btree without modification.
+ *
+ * Special Case #1: when growing the filesystem, we "free" an extent when
+ * growing the last AG. This extent is new space and so it is not tracked as
+ * used space in the btree. The growfs code will pass in an owner of
+ * XFS_RMAP_OWN_NULL to indicate that it expected that there is no owner of this
+ * extent. We verify that - the extent lookup result in a record that does not
+ * overlap.
+ *
+ * Special Case #2: EFIs do not record the owner of the extent, so when
+ * recovering EFIs from the log we pass in XFS_RMAP_OWN_UNKNOWN to tell the rmap
+ * btree to ignore the owner (i.e. wildcard match) so we don't trigger
+ * corruption checks during log recovery.
+ */
int
xfs_rmap_free(
struct xfs_trans *tp,
@@ -128,19 +146,156 @@ xfs_rmap_free(
struct xfs_owner_info *oinfo)
{
struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_btree_cur *cur;
+ struct xfs_rmap_irec ltrec;
+ uint64_t ltoff;
int error = 0;
+ int i;
+ uint64_t owner;
+ uint64_t offset;

if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
return 0;

trace_xfs_rmap_free_extent(mp, agno, bno, len, oinfo);
- if (1)
+ cur = xfs_rmapbt_init_cursor(mp, tp, agbp, agno);
+
+ xfs_owner_info_unpack(oinfo, &owner, &offset);
+
+ /*
+ * We should always have a left record because there's a static record
+ * for the AG headers at rm_startblock == 0 created by mkfs/growfs that
+ * will not ever be removed from the tree.
+ */
+ error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, &i);
+ if (error)
goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+
+ error = xfs_rmap_get_rec(cur, &ltrec, &i);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+ ltoff = ltrec.rm_offset & ~XFS_RMAP_OFF_BMBT;
+
+ /*
+ * For growfs, the incoming extent must be beyond the left record we
+ * just found as it is new space and won't be used by anyone. This is
+ * just a corruption check as we don't actually do anything with this
+ * extent.
+ */
+ if (owner == XFS_RMAP_OWN_NULL) {
+ XFS_WANT_CORRUPTED_GOTO(mp, bno > ltrec.rm_startblock +
+ ltrec.rm_blockcount, out_error);
+ goto out_done;
+ }
+
+ /* make sure the extent we found covers the entire freeing range. */
+ XFS_WANT_CORRUPTED_GOTO(mp, !XFS_RMAP_IS_UNWRITTEN(ltrec.rm_blockcount),
+ out_error);
+ XFS_WANT_CORRUPTED_GOTO(mp, ltrec.rm_startblock <= bno &&
+ ltrec.rm_startblock + XFS_RMAP_LEN(ltrec.rm_blockcount) >=
+ bno + len, out_error);
+
+ /* make sure the owner matches what we expect to find in the tree */
+ XFS_WANT_CORRUPTED_GOTO(mp, owner == ltrec.rm_owner ||
+ XFS_RMAP_NON_INODE_OWNER(owner), out_error);
+
+ /* check the offset, if necessary */
+ if (!XFS_RMAP_NON_INODE_OWNER(owner)) {
+ if (XFS_RMAP_IS_BMBT(offset)) {
+ XFS_WANT_CORRUPTED_GOTO(mp,
+ XFS_RMAP_IS_BMBT(ltrec.rm_offset),
+ out_error);
+ } else {
+ XFS_WANT_CORRUPTED_GOTO(mp,
+ ltrec.rm_offset <= offset, out_error);
+ XFS_WANT_CORRUPTED_GOTO(mp,
+ offset <= ltoff + ltrec.rm_blockcount,
+ out_error);
+ }
+ }
+
+ if (ltrec.rm_startblock == bno && ltrec.rm_blockcount == len) {
+ /* exact match, simply remove the record from rmap tree */
+ error = xfs_btree_delete(cur, &i);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+ } else if (ltrec.rm_startblock == bno) {
+ /*
+ * overlap left hand side of extent: move the start, trim the
+ * length and update the current record.
+ *
+ * ltbno ltlen
+ * Orig: |oooooooooooooooooooo|
+ * Freeing: |fffffffff|
+ * Result: |rrrrrrrrrr|
+ * bno len
+ */
+ ltrec.rm_startblock += len;
+ ltrec.rm_blockcount -= len;
+ error = xfs_rmap_update(cur, &ltrec);
+ if (error)
+ goto out_error;
+ } else if (ltrec.rm_startblock + ltrec.rm_blockcount == bno + len) {
+ /*
+ * overlap right hand side of extent: trim the length and update
+ * the current record.
+ *
+ * ltbno ltlen
+ * Orig: |oooooooooooooooooooo|
+ * Freeing: |fffffffff|
+ * Result: |rrrrrrrrrr|
+ * bno len
+ */
+ ltrec.rm_blockcount -= len;
+ error = xfs_rmap_update(cur, &ltrec);
+ if (error)
+ goto out_error;
+ } else {
+
+ /*
+ * overlap middle of extent: trim the length of the existing
+ * record to the length of the new left-extent size, increment
+ * the insertion position so we can insert a new record
+ * containing the remaining right-extent space.
+ *
+ * ltbno ltlen
+ * Orig: |oooooooooooooooooooo|
+ * Freeing: |fffffffff|
+ * Result: |rrrrr| |rrrr|
+ * bno len
+ */
+ xfs_extlen_t orig_len = ltrec.rm_blockcount;
+
+ ltrec.rm_blockcount = bno - ltrec.rm_startblock;
+ error = xfs_rmap_update(cur, &ltrec);
+ if (error)
+ goto out_error;
+
+ error = xfs_btree_increment(cur, 0, &i);
+ if (error)
+ goto out_error;
+
+ cur->bc_rec.r.rm_startblock = bno + len;
+ cur->bc_rec.r.rm_blockcount = orig_len - len -
+ ltrec.rm_blockcount;
+ cur->bc_rec.r.rm_owner = ltrec.rm_owner;
+ cur->bc_rec.r.rm_offset = offset;
+ error = xfs_btree_insert(cur, &i);
+ if (error)
+ goto out_error;
+ }
+
+out_done:
trace_xfs_rmap_free_extent_done(mp, agno, bno, len, oinfo);
+ xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
return 0;

out_error:
trace_xfs_rmap_free_extent_error(mp, agno, bno, len, oinfo);
+ xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
return error;
}

@@ -262,7 +417,6 @@ xfs_rmap_alloc(
ltrec.rm_blockcount += len;
if (gtrec.rm_owner == owner &&
bno + len == gtrec.rm_startblock) {
- //printk("add middle\n");
/*
* right edge also contiguous, delete right record
* and merge into left record.