[PATCH 036/119] xfs: add an extent to the rmap btree

Darrick J. Wong
2016-06-17T01:21:53Z

From: Dave Chinner <dchinner@redhat.com>

Now all the btree, free space and transaction infrastructure is in
place, we can finally add the code to insert reverse mappings to the
rmap btree. Freeing will be done in a separate patch, so just the
addition operation can be focussed on here.

v2: Update alloc function to handle non-shared file data. Isolate the
part that makes changes from the part that initializes the rmap
cursor; this will be useful for deferred updates.

[darrick: handle owner offsets when adding rmaps]
[dchinner: remove remaining debug printk statements]
[darrick: move unwritten bit to rm_offset]

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 | 225 +++++++++++++++++++++++++++++++++++++++-
fs/xfs/libxfs/xfs_rmap_btree.h | 1
fs/xfs/xfs_trace.h | 2
3 files changed, 223 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
index 0e1721a..196e952 100644
--- a/fs/xfs/libxfs/xfs_rmap.c
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -159,6 +159,218 @@ out_error:
return error;
}

+/*
+ * A mergeable rmap should have the same owner, cannot be unwritten, and
+ * must be a bmbt rmap if we're asking about a bmbt rmap.
+ */
+static bool
+xfs_rmap_is_mergeable(
+ struct xfs_rmap_irec *irec,
+ uint64_t owner,
+ uint64_t offset,
+ xfs_extlen_t len,
+ unsigned int flags)
+{
+ if (irec->rm_owner == XFS_RMAP_OWN_NULL)
+ return false;
+ if (irec->rm_owner != owner)
+ return false;
+ if ((flags & XFS_RMAP_UNWRITTEN) ^
+ (irec->rm_flags & XFS_RMAP_UNWRITTEN))
+ return false;
+ if ((flags & XFS_RMAP_ATTR_FORK) ^
+ (irec->rm_flags & XFS_RMAP_ATTR_FORK))
+ return false;
+ if ((flags & XFS_RMAP_BMBT_BLOCK) ^
+ (irec->rm_flags & XFS_RMAP_BMBT_BLOCK))
+ return false;
+ return true;
+}
+
+/*
+ * When we allocate a new block, the first thing we do is add a reference to
+ * the extent in the rmap btree. This takes the form of a [agbno, length,
+ * owner, offset] record. Flags are encoded in the high bits of the offset
+ * field.
+ */
+STATIC int
+__xfs_rmap_alloc(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t bno,
+ xfs_extlen_t len,
+ bool unwritten,
+ struct xfs_owner_info *oinfo)
+{
+ struct xfs_mount *mp = cur->bc_mp;
+ struct xfs_rmap_irec ltrec;
+ struct xfs_rmap_irec gtrec;
+ int have_gt;
+ int have_lt;
+ int error = 0;
+ int i;
+ uint64_t owner;
+ uint64_t offset;
+ unsigned int flags = 0;
+ bool ignore_off;
+
+ xfs_owner_info_unpack(oinfo, &owner, &offset, &flags);
+ ignore_off = XFS_RMAP_NON_INODE_OWNER(owner) ||
+ (flags & XFS_RMAP_BMBT_BLOCK);
+ if (unwritten)
+ flags |= XFS_RMAP_UNWRITTEN;
+ trace_xfs_rmap_alloc_extent(mp, cur->bc_private.a.agno, bno, len,
+ unwritten, oinfo);
+
+ /*
+ * For the initial lookup, look for and exact match or the left-adjacent
+ * record for our insertion point. This will also give us the record for
+ * start block contiguity tests.
+ */
+ error = xfs_rmap_lookup_le(cur, bno, len, owner, offset, flags,
+ &have_lt);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, have_lt == 1, out_error);
+
+ error = xfs_rmap_get_rec(cur, &ltrec, &have_lt);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, have_lt == 1, out_error);
+ trace_xfs_rmap_lookup_le_range_result(cur->bc_mp,
+ cur->bc_private.a.agno, ltrec.rm_startblock,
+ ltrec.rm_blockcount, ltrec.rm_owner,
+ ltrec.rm_offset, ltrec.rm_flags);
+
+ if (!xfs_rmap_is_mergeable(&ltrec, owner, offset, len, flags))
+ have_lt = 0;
+
+ XFS_WANT_CORRUPTED_GOTO(mp,
+ have_lt == 0 ||
+ ltrec.rm_startblock + ltrec.rm_blockcount <= bno, out_error);
+
+ /*
+ * Increment the cursor to see if we have a right-adjacent record to our
+ * insertion point. This will give us the record for end block
+ * contiguity tests.
+ */
+ error = xfs_btree_increment(cur, 0, &have_gt);
+ if (error)
+ goto out_error;
+ if (have_gt) {
+ error = xfs_rmap_get_rec(cur, &gtrec, &have_gt);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, have_gt == 1, out_error);
+ XFS_WANT_CORRUPTED_GOTO(mp, bno + len <= gtrec.rm_startblock,
+ out_error);
+ trace_xfs_rmap_map_gtrec(cur->bc_mp,
+ cur->bc_private.a.agno, gtrec.rm_startblock,
+ gtrec.rm_blockcount, gtrec.rm_owner,
+ gtrec.rm_offset, gtrec.rm_flags);
+ if (!xfs_rmap_is_mergeable(&gtrec, owner, offset, len, flags))
+ have_gt = 0;
+ }
+
+ /*
+ * Note: cursor currently points one record to the right of ltrec, even
+ * if there is no record in the tree to the right.
+ */
+ if (have_lt &&
+ ltrec.rm_startblock + ltrec.rm_blockcount == bno &&
+ (ignore_off || ltrec.rm_offset + ltrec.rm_blockcount == offset)) {
+ /*
+ * left edge contiguous, merge into left record.
+ *
+ * ltbno ltlen
+ * orig: |ooooooooo|
+ * adding: |aaaaaaaaa|
+ * result: |rrrrrrrrrrrrrrrrrrr|
+ * bno len
+ */
+ ltrec.rm_blockcount += len;
+ if (have_gt &&
+ bno + len == gtrec.rm_startblock &&
+ (ignore_off || offset + len == gtrec.rm_offset) &&
+ (unsigned long)ltrec.rm_blockcount + len +
+ gtrec.rm_blockcount <= XFS_RMAP_LEN_MAX) {
+ /*
+ * right edge also contiguous, delete right record
+ * and merge into left record.
+ *
+ * ltbno ltlen gtbno gtlen
+ * orig: |ooooooooo| |ooooooooo|
+ * adding: |aaaaaaaaa|
+ * result: |rrrrrrrrrrrrrrrrrrrrrrrrrrrrr|
+ */
+ ltrec.rm_blockcount += gtrec.rm_blockcount;
+ trace_xfs_rmapbt_delete(mp, cur->bc_private.a.agno,
+ gtrec.rm_startblock,
+ gtrec.rm_blockcount,
+ gtrec.rm_owner,
+ gtrec.rm_offset,
+ gtrec.rm_flags);
+ error = xfs_btree_delete(cur, &i);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+ }
+
+ /* point the cursor back to the left record and update */
+ error = xfs_btree_decrement(cur, 0, &have_gt);
+ if (error)
+ goto out_error;
+ error = xfs_rmap_update(cur, &ltrec);
+ if (error)
+ goto out_error;
+ } else if (have_gt &&
+ bno + len == gtrec.rm_startblock &&
+ (ignore_off || offset + len == gtrec.rm_offset)) {
+ /*
+ * right edge contiguous, merge into right record.
+ *
+ * gtbno gtlen
+ * Orig: |ooooooooo|
+ * adding: |aaaaaaaaa|
+ * Result: |rrrrrrrrrrrrrrrrrrr|
+ * bno len
+ */
+ gtrec.rm_startblock = bno;
+ gtrec.rm_blockcount += len;
+ if (!ignore_off)
+ gtrec.rm_offset = offset;
+ error = xfs_rmap_update(cur, &gtrec);
+ if (error)
+ goto out_error;
+ } else {
+ /*
+ * no contiguous edge with identical owner, insert
+ * new record at current cursor position.
+ */
+ cur->bc_rec.r.rm_startblock = bno;
+ cur->bc_rec.r.rm_blockcount = len;
+ cur->bc_rec.r.rm_owner = owner;
+ cur->bc_rec.r.rm_offset = offset;
+ cur->bc_rec.r.rm_flags = flags;
+ trace_xfs_rmapbt_insert(mp, cur->bc_private.a.agno, bno, len,
+ owner, offset, flags);
+ error = xfs_btree_insert(cur, &i);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+ }
+
+ trace_xfs_rmap_alloc_extent_done(mp, cur->bc_private.a.agno, bno, len,
+ unwritten, oinfo);
+out_error:
+ if (error)
+ trace_xfs_rmap_alloc_extent_error(mp, cur->bc_private.a.agno,
+ bno, len, unwritten, oinfo);
+ return error;
+}
+
+/*
+ * Add a reference to an extent in the rmap btree.
+ */
int
xfs_rmap_alloc(
struct xfs_trans *tp,
@@ -169,19 +381,22 @@ xfs_rmap_alloc(
struct xfs_owner_info *oinfo)
{
struct xfs_mount *mp = tp->t_mountp;
- int error = 0;
+ struct xfs_btree_cur *cur;
+ int error;

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

- trace_xfs_rmap_alloc_extent(mp, agno, bno, len, false, oinfo);
- if (1)
+ cur = xfs_rmapbt_init_cursor(mp, tp, agbp, agno);
+ error = __xfs_rmap_alloc(cur, bno, len, false, oinfo);
+ if (error)
goto out_error;
- trace_xfs_rmap_alloc_extent_done(mp, agno, bno, len, false, oinfo);
+
+ xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
return 0;

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

diff --git a/fs/xfs/libxfs/xfs_rmap_btree.h b/fs/xfs/libxfs/xfs_rmap_btree.h
index e926c6e..9d92da5 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.h
+++ b/fs/xfs/libxfs/xfs_rmap_btree.h
@@ -67,6 +67,7 @@ int xfs_rmap_lookup_eq(struct xfs_btree_cur *cur, xfs_agblock_t bno,
int xfs_rmap_get_rec(struct xfs_btree_cur *cur, struct xfs_rmap_irec *irec,
int *stat);

+/* functions for updating the rmapbt for bmbt blocks and AG btree blocks */
int xfs_rmap_alloc(struct xfs_trans *tp, struct xfs_buf *agbp,
xfs_agnumber_t agno, xfs_agblock_t bno, xfs_extlen_t len,
struct xfs_owner_info *oinfo);
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 6daafaf..3ebceb0 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -2549,6 +2549,8 @@ DEFINE_RMAPBT_EVENT(xfs_rmapbt_delete);
DEFINE_AG_ERROR_EVENT(xfs_rmapbt_insert_error);
DEFINE_AG_ERROR_EVENT(xfs_rmapbt_delete_error);
DEFINE_AG_ERROR_EVENT(xfs_rmapbt_update_error);
+DEFINE_RMAPBT_EVENT(xfs_rmap_lookup_le_range_result);
+DEFINE_RMAPBT_EVENT(xfs_rmap_map_gtrec);

#endif /* _TRACE_XFS_H */