[PATCH 14/20] xfs: add rmap btree operations

Dave Chinner
2015-06-03T06:05:21Z

Implement the generic btree operations needed to manipulate rmap
btree blocks. This is very similar to the per-ag freespace btree
implementation, and uses the AGFL for allocation and freeing of
blocks.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/libxfs/xfs_btree.h | 1 +
fs/xfs/libxfs/xfs_rmap.c | 58 ++++++++++++
fs/xfs/libxfs/xfs_rmap_btree.c | 204 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 263 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 67e2bbd..48ab2b1 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -204,6 +204,7 @@ typedef struct xfs_btree_cur
xfs_alloc_rec_incore_t a;
xfs_bmbt_irec_t b;
xfs_inobt_rec_incore_t i;
+ struct xfs_rmap_irec r;
} bc_rec; /* current insert/search record value */
struct xfs_buf *bc_bufs[XFS_BTREE_MAXLEVELS]; /* buf ptr per level */
int bc_ptrs[XFS_BTREE_MAXLEVELS]; /* key/record # */
diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
index 3958cf8..38a92a1 100644
--- a/fs/xfs/libxfs/xfs_rmap.c
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -36,6 +36,64 @@
#include "xfs_error.h"
#include "xfs_extent_busy.h"

+/*
+ * Lookup the first record less than or equal to [bno, len]
+ * in the btree given by cur.
+ */
+STATIC int
+xfs_rmap_lookup_le(
+ struct xfs_btree_cur *cur,
+ xfs_agblock_t bno,
+ xfs_extlen_t len,
+ uint64_t owner,
+ int *stat)
+{
+ cur->bc_rec.r.rm_startblock = bno;
+ cur->bc_rec.r.rm_blockcount = len;
+ cur->bc_rec.r.rm_owner = owner;
+ return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
+}
+
+/*
+ * Update the record referred to by cur to the value given
+ * by [bno, len, ref].
+ * This either works (return 0) or gets an EFSCORRUPTED error.
+ */
+STATIC int
+xfs_rmap_update(
+ struct xfs_btree_cur *cur,
+ struct xfs_rmap_irec *irec)
+{
+ union xfs_btree_rec rec;
+
+ rec.rmap.rm_startblock = cpu_to_be32(irec->rm_startblock);
+ rec.rmap.rm_blockcount = cpu_to_be32(irec->rm_blockcount);
+ rec.rmap.rm_owner = cpu_to_be64(irec->rm_owner);
+ return xfs_btree_update(cur, &rec);
+}
+
+/*
+ * Get the data from the pointed-to record.
+ */
+STATIC int
+xfs_rmap_get_rec(
+ struct xfs_btree_cur *cur,
+ struct xfs_rmap_irec *irec,
+ int *stat)
+{
+ union xfs_btree_rec *rec;
+ int error;
+
+ error = xfs_btree_get_rec(cur, &rec, stat);
+ if (error || !*stat)
+ return error;
+
+ irec->rm_startblock = be32_to_cpu(rec->rmap.rm_startblock);
+ irec->rm_blockcount = be32_to_cpu(rec->rmap.rm_blockcount);
+ irec->rm_owner = be64_to_cpu(rec->rmap.rm_owner);
+ return 0;
+}
+
int
xfs_rmap_free(
struct xfs_trans *tp,
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
index 9a02699..0b396e6 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.c
+++ b/fs/xfs/libxfs/xfs_rmap_btree.c
@@ -34,6 +34,26 @@
#include "xfs_error.h"
#include "xfs_extent_busy.h"

+/*
+ * Reverse map btree.
+ *
+ * This is a per-ag tree used to track the owner of a given extent. Owner
+ * records are inserted when an extent is allocated, and removed when an extent
+ * is freed. There can only be one owner of an extent, usually an inode or some
+ * other metadata structure like a AG btree.
+ *
+ * The rmap btree is part of the free space management, so blocks for the tree
+ * are sourced from the agfl. Hence we need transaction reservation support for
+ * this tree so that the freelist is always large enough. This also impacts on
+ * the minimum space we need to leave free in the AG.
+ *
+ * The tree is ordered by block number - there's no need to order/search by
+ * extent size for online updating/management of the tree, and the reverse
+ * lookups are going to be "who owns this block" and so are by-block ordering is
+ * perfect for this.
+ *
+ */
+
static struct xfs_btree_cur *
xfs_rmapbt_dup_cursor(
struct xfs_btree_cur *cur)
@@ -42,6 +62,153 @@ xfs_rmapbt_dup_cursor(
cur->bc_private.a.agbp, cur->bc_private.a.agno);
}

+STATIC void
+xfs_rmapbt_set_root(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *ptr,
+ int inc)
+{
+ struct xfs_buf *agbp = cur->bc_private.a.agbp;
+ struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp);
+ xfs_agnumber_t seqno = be32_to_cpu(agf->agf_seqno);
+ int btnum = cur->bc_btnum;
+ struct xfs_perag *pag = xfs_perag_get(cur->bc_mp, seqno);
+
+ ASSERT(ptr->s != 0);
+
+ agf->agf_roots[btnum] = ptr->s;
+ be32_add_cpu(&agf->agf_levels[btnum], inc);
+ pag->pagf_levels[btnum] += inc;
+ xfs_perag_put(pag);
+
+ xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_ROOTS | XFS_AGF_LEVELS);
+}
+
+STATIC int
+xfs_rmapbt_alloc_block(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *start,
+ union xfs_btree_ptr *new,
+ int *stat)
+{
+ int error;
+ xfs_agblock_t bno;
+
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+
+ /* Allocate the new block from the freelist. If we can't, give up. */
+ error = xfs_alloc_get_freelist(cur->bc_tp, cur->bc_private.a.agbp,
+ &bno, 1);
+ if (error) {
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+ return error;
+ }
+
+ if (bno == NULLAGBLOCK) {
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+ *stat = 0;
+ return 0;
+ }
+
+ xfs_extent_busy_reuse(cur->bc_mp, cur->bc_private.a.agno, bno, 1, false);
+
+ xfs_trans_agbtree_delta(cur->bc_tp, 1);
+ new->s = cpu_to_be32(bno);
+
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+ *stat = 1;
+ return 0;
+}
+
+STATIC int
+xfs_rmapbt_free_block(
+ struct xfs_btree_cur *cur,
+ struct xfs_buf *bp)
+{
+ struct xfs_buf *agbp = cur->bc_private.a.agbp;
+ struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp);
+ xfs_agblock_t bno;
+ int error;
+
+ bno = xfs_daddr_to_agbno(cur->bc_mp, XFS_BUF_ADDR(bp));
+ error = xfs_alloc_put_freelist(cur->bc_tp, agbp, NULL, bno, 1);
+ if (error)
+ return error;
+
+ xfs_extent_busy_insert(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1,
+ XFS_EXTENT_BUSY_SKIP_DISCARD);
+ xfs_trans_agbtree_delta(cur->bc_tp, -1);
+
+ xfs_trans_binval(cur->bc_tp, bp);
+ return 0;
+}
+
+STATIC int
+xfs_rmapbt_get_minrecs(
+ struct xfs_btree_cur *cur,
+ int level)
+{
+ return cur->bc_mp->m_rmap_mnr[level != 0];
+}
+
+STATIC int
+xfs_rmapbt_get_maxrecs(
+ struct xfs_btree_cur *cur,
+ int level)
+{
+ return cur->bc_mp->m_rmap_mxr[level != 0];
+}
+
+STATIC void
+xfs_rmapbt_init_key_from_rec(
+ union xfs_btree_key *key,
+ union xfs_btree_rec *rec)
+{
+ key->rmap.rm_startblock = rec->rmap.rm_startblock;
+}
+
+STATIC void
+xfs_rmapbt_init_rec_from_key(
+ union xfs_btree_key *key,
+ union xfs_btree_rec *rec)
+{
+ rec->rmap.rm_startblock = key->rmap.rm_startblock;
+}
+
+STATIC void
+xfs_rmapbt_init_rec_from_cur(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_rec *rec)
+{
+ rec->rmap.rm_startblock = cpu_to_be32(cur->bc_rec.r.rm_startblock);
+ rec->rmap.rm_blockcount = cpu_to_be32(cur->bc_rec.r.rm_blockcount);
+ rec->rmap.rm_owner = cpu_to_be64(cur->bc_rec.r.rm_owner);
+}
+
+STATIC void
+xfs_rmapbt_init_ptr_from_cur(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *ptr)
+{
+ struct xfs_agf *agf = XFS_BUF_TO_AGF(cur->bc_private.a.agbp);
+
+ ASSERT(cur->bc_private.a.agno == be32_to_cpu(agf->agf_seqno));
+ ASSERT(agf->agf_roots[cur->bc_btnum] != 0);
+
+ ptr->s = agf->agf_roots[cur->bc_btnum];
+}
+
+STATIC __int64_t
+xfs_rmapbt_key_diff(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_key *key)
+{
+ struct xfs_rmap_irec *rec = &cur->bc_rec.r;
+ struct xfs_rmap_key *kp = &key->rmap;
+
+ return (__int64_t)be32_to_cpu(kp->rm_startblock) - rec->rm_startblock;
+}
+
static bool
xfs_rmapbt_verify(
struct xfs_buf *bp)
@@ -133,12 +300,49 @@ const struct xfs_buf_ops xfs_rmapbt_buf_ops = {
.verify_write = xfs_rmapbt_write_verify,
};

+#if defined(DEBUG) || defined(XFS_WARN)
+STATIC int
+xfs_rmapbt_keys_inorder(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_key *k1,
+ union xfs_btree_key *k2)
+{
+ return be32_to_cpu(k1->rmap.rm_startblock) <
+ be32_to_cpu(k2->rmap.rm_startblock);
+}
+
+STATIC int
+xfs_rmapbt_recs_inorder(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_rec *r1,
+ union xfs_btree_rec *r2)
+{
+ return be32_to_cpu(r1->rmap.rm_startblock) +
+ be32_to_cpu(r1->rmap.rm_blockcount) <=
+ be32_to_cpu(r2->rmap.rm_startblock);
+}
+#endif /* DEBUG */
+
static const struct xfs_btree_ops xfs_rmapbt_ops = {
.rec_len = sizeof(struct xfs_rmap_rec),
.key_len = sizeof(struct xfs_rmap_key),

.dup_cursor = xfs_rmapbt_dup_cursor,
+ .set_root = xfs_rmapbt_set_root,
+ .alloc_block = xfs_rmapbt_alloc_block,
+ .free_block = xfs_rmapbt_free_block,
+ .get_minrecs = xfs_rmapbt_get_minrecs,
+ .get_maxrecs = xfs_rmapbt_get_maxrecs,
+ .init_key_from_rec = xfs_rmapbt_init_key_from_rec,
+ .init_rec_from_key = xfs_rmapbt_init_rec_from_key,
+ .init_rec_from_cur = xfs_rmapbt_init_rec_from_cur,
+ .init_ptr_from_cur = xfs_rmapbt_init_ptr_from_cur,
+ .key_diff = xfs_rmapbt_key_diff,
.buf_ops = &xfs_rmapbt_buf_ops,
+#if defined(DEBUG) || defined(XFS_WARN)
+ .keys_inorder = xfs_rmapbt_keys_inorder,
+ .recs_inorder = xfs_rmapbt_recs_inorder,
+#endif
};

/*