[XFS] implement generic xfs_btree_lookup

From: Dave Chinner <dgc@sgi.com>

[hch: split out from bigger patch and minor adaptions]

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32192a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Bill O'Donnell <billodo@sgi.com>
Signed-off-by: David Chinner <david@fromorbit.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index 7ca6903e2354..6bda0ae26c2a 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -90,6 +90,54 @@ STATIC int xfs_alloc_ag_vextent_small(xfs_alloc_arg_t *,
  */
 
 /*
+ * Lookup the record equal to [bno, len] in the btree given by cur.
+ */
+STATIC int                              /* error */
+xfs_alloc_lookup_eq(
+        struct xfs_btree_cur    *cur,   /* btree cursor */
+        xfs_agblock_t           bno,    /* starting block of extent */
+        xfs_extlen_t            len,    /* length of extent */
+        int                     *stat)  /* success/failure */
+{
+        cur->bc_rec.a.ar_startblock = bno;
+        cur->bc_rec.a.ar_blockcount = len;
+        return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
+}
+
+/*
+ * Lookup the first record greater than or equal to [bno, len]
+ * in the btree given by cur.
+ */
+STATIC int                              /* error */
+xfs_alloc_lookup_ge(
+        struct xfs_btree_cur    *cur,   /* btree cursor */
+        xfs_agblock_t           bno,    /* starting block of extent */
+        xfs_extlen_t            len,    /* length of extent */
+        int                     *stat)  /* success/failure */
+{
+        cur->bc_rec.a.ar_startblock = bno;
+        cur->bc_rec.a.ar_blockcount = len;
+        return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
+}
+
+/*
+ * Lookup the first record less than or equal to [bno, len]
+ * in the btree given by cur.
+ */
+STATIC int                              /* error */
+xfs_alloc_lookup_le(
+        struct xfs_btree_cur    *cur,   /* btree cursor */
+        xfs_agblock_t           bno,    /* starting block of extent */
+        xfs_extlen_t            len,    /* length of extent */
+        int                     *stat)  /* success/failure */
+{
+        cur->bc_rec.a.ar_startblock = bno;
+        cur->bc_rec.a.ar_blockcount = len;
+        return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
+}
+
+
+/*
  * Compute aligned version of the found extent.
  * Takes alignment and min length into account.
  */