man: document the xfs_db btheight command

Document the btheight command in xfs_db.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/man/man8/xfs_db.8 b/man/man8/xfs_db.8
index a1ee3514f40f21e5510a87e0dea8f1e7c70a02c9..53e34983de8e0af833e06b791cc046b220ed9796 100644 (file)
--- a/man/man8/xfs_db.8
+++ b/man/man8/xfs_db.8
@@ -346,6 +346,45 @@ If the cursor points at an inode, dump the extended attribute block mapping btre
 Dump all keys and pointers in intermediate btree nodes, and all records in leaf btree nodes.
 .RE
 .TP
+.BI "btheight [\-b " blksz "] [\-n " recs "] [\-w " max "|\-w " min "] btree types..."
+For a given number of btree records and a btree type, report the number of
+records and blocks for each level of the btree, and the total number of blocks.
+The btree type must be given after the options.
+
+A raw btree geometry can be provided in the format
+"record_bytes:key_bytes:ptr_bytes:header_type", where header_type is one of
+"short", "long", "shortcrc", or "longcrc".
+
+The supported btree types are:
+.IR bnobt ,
+.IR cntbt ,
+.IR inobt ,
+.IR finobt ,
+.IR bmapbt ,
+.IR refcountbt ,
+and
+.IR rmapbt .
+
+Options are as follows:
+.RS 1.0i
+.TP 0.4i
+.B \-b
+is used to override the btree block size.
+The default is the filesystem block size.
+.TP
+.B \-n
+is used to specify the number of records to store.
+This argument is required.
+.TP
+.B \-w max
+shows only the best case scenario, which is when the btree blocks are
+maximally loaded.
+.TP
+.B \-w min
+shows only the worst case scenario, which is when the btree blocks are
+half full.
+.RE
+.TP
 .B check
 See the
 .B blockget