xfs: account for log space when formatting new AGs

When we're writing out a fresh new AG, make sure that we don't list an
internal log as free and that we create the rmap for the region.  growfs
never does this, but we will need it when we hook up mkfs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_ag.c

@@ -10,6 +10,7 @@
 #include "xfs_shared.h"
 #include "xfs_format.h"
 #include "xfs_trans_resv.h"
+#include "xfs_bit.h"
 #include "xfs_sb.h"
 #include "xfs_mount.h"
 #include "xfs_btree.h"
@@ -44,6 +45,12 @@ xfs_get_aghdr_buf(
 	return bp;
 }
 
+static inline bool is_log_ag(struct xfs_mount *mp, struct aghdr_init_data *id)
+{
+	return mp->m_sb.sb_logstart > 0 &&
+	       id->agno == XFS_FSB_TO_AGNO(mp, mp->m_sb.sb_logstart);
+}
+
 /*
  * Generic btree root block init function
  */
@@ -64,11 +71,51 @@ xfs_freesp_init_recs(
 	struct aghdr_init_data	*id)
 {
 	struct xfs_alloc_rec	*arec;
+	struct xfs_btree_block	*block = XFS_BUF_TO_BLOCK(bp);
 
 	arec = XFS_ALLOC_REC_ADDR(mp, XFS_BUF_TO_BLOCK(bp), 1);
 	arec->ar_startblock = cpu_to_be32(mp->m_ag_prealloc_blocks);
+
+	if (is_log_ag(mp, id)) {
+		struct xfs_alloc_rec	*nrec;
+		xfs_agblock_t		start = XFS_FSB_TO_AGBNO(mp,
+							mp->m_sb.sb_logstart);
+
+		ASSERT(start >= mp->m_ag_prealloc_blocks);
+		if (start != mp->m_ag_prealloc_blocks) {
+			/*
+			 * Modify first record to pad stripe align of log
+			 */
+			arec->ar_blockcount = cpu_to_be32(start -
+						mp->m_ag_prealloc_blocks);
+			nrec = arec + 1;
+
+			/*
+			 * Insert second record at start of internal log
+			 * which then gets trimmed.
+			 */
+			nrec->ar_startblock = cpu_to_be32(
+					be32_to_cpu(arec->ar_startblock) +
+					be32_to_cpu(arec->ar_blockcount));
+			arec = nrec;
+			be16_add_cpu(&block->bb_numrecs, 1);
+		}
+		/*
+		 * Change record start to after the internal log
+		 */
+		be32_add_cpu(&arec->ar_startblock, mp->m_sb.sb_logblocks);
+	}
+
+	/*
+	 * Calculate the record block count and check for the case where
+	 * the log might have consumed all available space in the AG. If
+	 * so, reset the record count to 0 to avoid exposure of an invalid
+	 * record start block.
+	 */
 	arec->ar_blockcount = cpu_to_be32(id->agsize -
 					  be32_to_cpu(arec->ar_startblock));
+	if (!arec->ar_blockcount)
+		block->bb_numrecs = 0;
 }
 
 /*
@@ -154,6 +201,18 @@ xfs_rmaproot_init(
 		rrec->rm_offset = 0;
 		be16_add_cpu(&block->bb_numrecs, 1);
 	}
+
+	/* account for the log space */
+	if (is_log_ag(mp, id)) {
+		rrec = XFS_RMAP_REC_ADDR(block,
+				be16_to_cpu(block->bb_numrecs) + 1);
+		rrec->rm_startblock = cpu_to_be32(
+				XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart));
+		rrec->rm_blockcount = cpu_to_be32(mp->m_sb.sb_logblocks);
+		rrec->rm_owner = cpu_to_be64(XFS_RMAP_OWN_LOG);
+		rrec->rm_offset = 0;
+		be16_add_cpu(&block->bb_numrecs, 1);
+	}
 }
 
 /*
@@ -214,6 +273,14 @@ xfs_agfblock_init(
 		agf->agf_refcount_level = cpu_to_be32(1);
 		agf->agf_refcount_blocks = cpu_to_be32(1);
 	}
+
+	if (is_log_ag(mp, id)) {
+		int64_t	logblocks = mp->m_sb.sb_logblocks;
+
+		be32_add_cpu(&agf->agf_freeblks, -logblocks);
+		agf->agf_longest = cpu_to_be32(id->agsize -
+			XFS_FSB_TO_AGBNO(mp, mp->m_sb.sb_logstart) - logblocks);
+	}
 }
 
 static void