[PATCH v2 6/7] xfs_repair: throw away totally bad clusters

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

If the filesystem supports sparse inodes, we detect that an entire
cluster buffer has no detectable inodes at all, and we can easily mark
that part of the inode chunk sparse, just drop the cluster buffer and
forget about it.  This makes repair less likely to go to great lengths
to try to save something that's totally unsalvageable.

This manifested in recs[2].free=zeroes in xfs/364, wherein the root
directory claimed to own block X and the inobt also claimed that X was
inodes; repair tried to create rmaps for both owners, and then the whole
mess blew up because the rmap code aborts on those kinds of anomalies.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
v2: drop repair/rmap.c paste error
---
 repair/dino_chunks.c |   35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/repair/dino_chunks.c b/repair/dino_chunks.c
index 50a2003614df..e4a95ff635c8 100644
--- a/repair/dino_chunks.c
+++ b/repair/dino_chunks.c
@@ -601,6 +601,7 @@ process_inode_chunk(
 	xfs_dinode_t		*dino;
 	int			icnt;
 	int			status;
+	int			bp_found;
 	int			is_used;
 	int			ino_dirty;
 	int			irec_offset;
@@ -614,6 +615,7 @@ process_inode_chunk(
 	int			bp_index;
 	int			cluster_offset;
 	struct xfs_ino_geometry	*igeo = M_IGEO(mp);
+	bool			can_punch_sparse = false;
 	int			error;
 
 	ASSERT(first_irec != NULL);
@@ -626,6 +628,10 @@ process_inode_chunk(
 	if (cluster_count == 0)
 		cluster_count = 1;
 
+	if (xfs_sb_version_hassparseinodes(&mp->m_sb) &&
+	    M_IGEO(mp)->inodes_per_cluster >= XFS_INODES_PER_HOLEMASK_BIT)
+		can_punch_sparse = true;
+
 	/*
 	 * get all blocks required to read in this chunk (may wind up
 	 * having to process more chunks in a multi-chunk per block fs)
@@ -700,6 +706,7 @@ process_inode_chunk(
 	cluster_offset = 0;
 	icnt = 0;
 	status = 0;
+	bp_found = 0;
 	bp_index = 0;
 
 	/*
@@ -725,8 +732,10 @@ process_inode_chunk(
 						(agno == 0 &&
 						(mp->m_sb.sb_rootino == agino ||
 						 mp->m_sb.sb_rsumino == agino ||
-						 mp->m_sb.sb_rbmino == agino)))
+						 mp->m_sb.sb_rbmino == agino))) {
 					status++;
+					bp_found++;
+				}
 			}
 
 			irec_offset++;
@@ -749,11 +758,35 @@ process_inode_chunk(
 				irec_offset = 0;
 			}
 			if (cluster_offset == M_IGEO(mp)->inodes_per_cluster) {
+				if (can_punch_sparse &&
+				    bplist[bp_index] != NULL &&
+				    bp_found == 0) {
+					/*
+					 * We didn't find any good inodes in
+					 * this cluster, blow it away before
+					 * moving on to the next one.
+					 */
+					libxfs_buf_relse(bplist[bp_index]);
+					bplist[bp_index] = NULL;
+				}
 				bp_index++;
 				cluster_offset = 0;
+				bp_found = 0;
 			}
 		}
 
+		if (can_punch_sparse &&
+		    bp_index < cluster_count &&
+		    bplist[bp_index] != NULL &&
+		    bp_found == 0) {
+			/*
+			 * We didn't find any good inodes in this cluster, blow
+			 * it away.
+			 */
+			libxfs_buf_relse(bplist[bp_index]);
+			bplist[bp_index] = NULL;
+		}
+
 		/*
 		 * if chunk/block is bad, blow it off.  the inode records
 		 * will be deleted by the caller if appropriate.