[XFS] implement generic xfs_btree_increment
From: Dave Chinner <dgc@sgi.com>
Because this is the first major generic btree routine this patch includes
some infrastrucure, first a few routines to deal with a btree block that
can be either in short or long form, second xfs_btree_read_buf_block,
which is the new central routine to read a btree block given a cursor, and
third the new xfs_btree_ptr_addr routine to calculate the address for a
given btree pointer record.
[hch: split out from bigger patch and minor adaptions]
SGI-PV: 985583
SGI-Modid: xfs-linux-melb:xfs-kern:32190a
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>
diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c
index 4aec7c7..e9ab86b 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -35,6 +35,7 @@
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
+#include "xfs_btree_trace.h"
#include "xfs_ialloc.h"
#include "xfs_error.h"
@@ -949,3 +950,224 @@
cur->bc_ra[lev] |= XFS_BTCUR_RIGHTRA;
}
}
+
+STATIC int
+xfs_btree_ptr_is_null(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *ptr)
+{
+ if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
+ return be64_to_cpu(ptr->l) == NULLFSBLOCK;
+ else
+ return be32_to_cpu(ptr->s) == NULLAGBLOCK;
+}
+
+/*
+ * Get/set/init sibling pointers
+ */
+STATIC void
+xfs_btree_get_sibling(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_block *block,
+ union xfs_btree_ptr *ptr,
+ int lr)
+{
+ ASSERT(lr == XFS_BB_LEFTSIB || lr == XFS_BB_RIGHTSIB);
+
+ if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
+ if (lr == XFS_BB_RIGHTSIB)
+ ptr->l = block->bb_u.l.bb_rightsib;
+ else
+ ptr->l = block->bb_u.l.bb_leftsib;
+ } else {
+ if (lr == XFS_BB_RIGHTSIB)
+ ptr->s = block->bb_u.s.bb_rightsib;
+ else
+ ptr->s = block->bb_u.s.bb_leftsib;
+ }
+}
+
+STATIC xfs_daddr_t
+xfs_btree_ptr_to_daddr(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *ptr)
+{
+ if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
+ ASSERT(be64_to_cpu(ptr->l) != NULLFSBLOCK);
+
+ return XFS_FSB_TO_DADDR(cur->bc_mp, be64_to_cpu(ptr->l));
+ } else {
+ ASSERT(cur->bc_private.a.agno != NULLAGNUMBER);
+ ASSERT(be32_to_cpu(ptr->s) != NULLAGBLOCK);
+
+ return XFS_AGB_TO_DADDR(cur->bc_mp, cur->bc_private.a.agno,
+ be32_to_cpu(ptr->s));
+ }
+}
+
+STATIC void
+xfs_btree_set_refs(
+ struct xfs_btree_cur *cur,
+ struct xfs_buf *bp)
+{
+ switch (cur->bc_btnum) {
+ case XFS_BTNUM_BNO:
+ case XFS_BTNUM_CNT:
+ XFS_BUF_SET_VTYPE_REF(*bpp, B_FS_MAP, XFS_ALLOC_BTREE_REF);
+ break;
+ case XFS_BTNUM_INO:
+ XFS_BUF_SET_VTYPE_REF(*bpp, B_FS_INOMAP, XFS_INO_BTREE_REF);
+ break;
+ case XFS_BTNUM_BMAP:
+ XFS_BUF_SET_VTYPE_REF(*bpp, B_FS_MAP, XFS_BMAP_BTREE_REF);
+ break;
+ default:
+ ASSERT(0);
+ }
+}
+
+/*
+ * Read in the buffer at the given ptr and return the buffer and
+ * the block pointer within the buffer.
+ */
+STATIC int
+xfs_btree_read_buf_block(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *ptr,
+ int level,
+ int flags,
+ struct xfs_btree_block **block,
+ struct xfs_buf **bpp)
+{
+ struct xfs_mount *mp = cur->bc_mp;
+ xfs_daddr_t d;
+ int error;
+
+ /* need to sort out how callers deal with failures first */
+ ASSERT(!(flags & XFS_BUF_TRYLOCK));
+
+ d = xfs_btree_ptr_to_daddr(cur, ptr);
+ error = xfs_trans_read_buf(mp, cur->bc_tp, mp->m_ddev_targp, d,
+ mp->m_bsize, flags, bpp);
+ if (error)
+ return error;
+
+ ASSERT(*bpp != NULL);
+ ASSERT(!XFS_BUF_GETERROR(*bpp));
+
+ xfs_btree_set_refs(cur, *bpp);
+ *block = XFS_BUF_TO_BLOCK(*bpp);
+
+ error = xfs_btree_check_block(cur, *block, level, *bpp);
+ if (error)
+ xfs_trans_brelse(cur->bc_tp, *bpp);
+ return error;
+}
+
+/*
+ * Increment cursor by one record at the level.
+ * For nonzero levels the leaf-ward information is untouched.
+ */
+int /* error */
+xfs_btree_increment(
+ struct xfs_btree_cur *cur,
+ int level,
+ int *stat) /* success/failure */
+{
+ struct xfs_btree_block *block;
+ union xfs_btree_ptr ptr;
+ struct xfs_buf *bp;
+ int error; /* error return value */
+ int lev;
+
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+ XFS_BTREE_TRACE_ARGI(cur, level);
+
+ ASSERT(level < cur->bc_nlevels);
+
+ /* Read-ahead to the right at this level. */
+ xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
+
+ /* Get a pointer to the btree block. */
+ block = xfs_btree_get_block(cur, level, &bp);
+
+#ifdef DEBUG
+ error = xfs_btree_check_block(cur, block, level, bp);
+ if (error)
+ goto error0;
+#endif
+
+ /* We're done if we remain in the block after the increment. */
+ if (++cur->bc_ptrs[level] <= xfs_btree_get_numrecs(block))
+ goto out1;
+
+ /* Fail if we just went off the right edge of the tree. */
+ xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
+ if (xfs_btree_ptr_is_null(cur, &ptr))
+ goto out0;
+
+ XFS_BTREE_STATS_INC(cur, increment);
+
+ /*
+ * March up the tree incrementing pointers.
+ * Stop when we don't go off the right edge of a block.
+ */
+ for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
+ block = xfs_btree_get_block(cur, lev, &bp);
+
+#ifdef DEBUG
+ error = xfs_btree_check_block(cur, block, lev, bp);
+ if (error)
+ goto error0;
+#endif
+
+ if (++cur->bc_ptrs[lev] <= xfs_btree_get_numrecs(block))
+ break;
+
+ /* Read-ahead the right block for the next loop. */
+ xfs_btree_readahead(cur, lev, XFS_BTCUR_RIGHTRA);
+ }
+
+ /*
+ * If we went off the root then we are either seriously
+ * confused or have the tree root in an inode.
+ */
+ if (lev == cur->bc_nlevels) {
+ if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
+ goto out0;
+ ASSERT(0);
+ error = EFSCORRUPTED;
+ goto error0;
+ }
+ ASSERT(lev < cur->bc_nlevels);
+
+ /*
+ * Now walk back down the tree, fixing up the cursor's buffer
+ * pointers and key numbers.
+ */
+ for (block = xfs_btree_get_block(cur, lev, &bp); lev > level; ) {
+ union xfs_btree_ptr *ptrp;
+
+ ptrp = xfs_btree_ptr_addr(cur, cur->bc_ptrs[lev], block);
+ error = xfs_btree_read_buf_block(cur, ptrp, --lev,
+ 0, &block, &bp);
+ if (error)
+ goto error0;
+
+ xfs_btree_setbuf(cur, lev, bp);
+ cur->bc_ptrs[lev] = 1;
+ }
+out1:
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+ *stat = 1;
+ return 0;
+
+out0:
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+ *stat = 0;
+ return 0;
+
+error0:
+ XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+ return error;
+}