[PATCH 4/5] ext4: Mark block group as corrupt on inode bitmap error

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

If we detect either a discrepancy between the inode bitmap and the inode counts
or the inode bitmap fails to pass validation checks, mark the block group
corrupt and refuse to allocate or deallocate inodes from the group.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/ext4/ext4.h   |    3 +++
 fs/ext4/ialloc.c |   29 +++++++++++++++++++++++++----
 2 files changed, 28 insertions(+), 4 deletions(-)


diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 45cc955..b8ac53d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2449,11 +2449,14 @@ struct ext4_group_info {
 #define EXT4_GROUP_INFO_NEED_INIT_BIT		0
 #define EXT4_GROUP_INFO_WAS_TRIMMED_BIT		1
 #define EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT	2
+#define EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT	4
 
 #define EXT4_MB_GRP_NEED_INIT(grp)	\
 	(test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
 #define EXT4_MB_GRP_BBITMAP_CORRUPT(grp)	\
 	(test_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &((grp)->bb_state)))
+#define EXT4_MB_GRP_IBITMAP_CORRUPT(grp)	\
+	(test_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &((grp)->bb_state)))
 
 #define EXT4_MB_GRP_WAS_TRIMMED(grp)	\
 	(test_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index f03598c..08c7fa7 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -117,6 +117,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
 	struct ext4_group_desc *desc;
 	struct buffer_head *bh = NULL;
 	ext4_fsblk_t bitmap_blk;
+	struct ext4_group_info *grp;
 
 	desc = ext4_get_group_desc(sb, block_group, NULL);
 	if (!desc)
@@ -185,6 +186,8 @@ verify:
 		put_bh(bh);
 		ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "
 			   "inode_bitmap = %llu", block_group, bitmap_blk);
+		grp = ext4_get_group_info(sb, block_group);
+		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
 		return NULL;
 	}
 	ext4_unlock_group(sb, block_group);
@@ -221,6 +224,7 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
 	struct ext4_super_block *es;
 	struct ext4_sb_info *sbi;
 	int fatal = 0, err, count, cleared;
+	struct ext4_group_info *grp;
 
 	if (!sb) {
 		printk(KERN_ERR "EXT4-fs: %s:%d: inode on "
@@ -266,7 +270,9 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
 	block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
 	bit = (ino - 1) % EXT4_INODES_PER_GROUP(sb);
 	bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
-	if (!bitmap_bh)
+	/* Don't bother if the inode bitmap is corrupt. */
+	grp = ext4_get_group_info(sb, block_group);
+	if (unlikely(EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) || !bitmap_bh)
 		goto error_return;
 
 	BUFFER_TRACE(bitmap_bh, "get_write_access");
@@ -315,8 +321,10 @@ out:
 		err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
 		if (!fatal)
 			fatal = err;
-	} else
+	} else {
 		ext4_error(sb, "bit already cleared for inode %lu", ino);
+		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
+	}
 
 error_return:
 	brelse(bitmap_bh);
@@ -652,6 +660,7 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 	struct inode *ret;
 	ext4_group_t i;
 	ext4_group_t flex_group;
+	struct ext4_group_info *grp;
 
 	/* Cannot create files in a deleted directory */
 	if (!dir || !dir->i_nlink)
@@ -725,10 +734,22 @@ got_group:
 			continue;
 		}
 
+		grp = ext4_get_group_info(sb, group);
+		/* Skip groups with already-known suspicious inode tables */
+		if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
+			if (++group == ngroups)
+				group = 0;
+			continue;
+		}
+
 		brelse(inode_bitmap_bh);
 		inode_bitmap_bh = ext4_read_inode_bitmap(sb, group);
-		if (!inode_bitmap_bh)
-			goto out;
+		/* Skip groups with suspicious inode tables */
+		if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp) || !inode_bitmap_bh) {
+			if (++group == ngroups)
+				group = 0;
+			continue;
+		}
 
 repeat_in_this_group:
 		ino = ext4_find_next_zero_bit((unsigned long *)