xfs: return a 64-bit block count from xfs_btree_count_blocks

With the nrext64 feature enabled, it's possible for a data fork to have
2^48 extent mappings.  Even with a 64k fsblock size, that maps out to
a bmbt containing more than 2^32 blocks.  Therefore, this predicate must
return a u64 count to avoid an integer wraparound that will cause scrub
to do the wrong thing.

It's unlikely that any such filesystem currently exists, because the
incore bmbt would consume more than 64GB of kernel memory on its own,
and so far nobody except me has driven a filesystem that far, judging
from the lack of complaints.

Cc: <[email protected]> # v5.19
Fixes: df9ad5cc7a5240 ("xfs: Introduce macros to represent new maximum extent counts for data/attr forks")
Signed-off-by: "Darrick J. Wong" <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>

3 files changed, 6 insertions, 4 deletions

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 2b5fc5fd1643..c748866ef923 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -5144,7 +5144,7 @@ xfs_btree_count_blocks_helper(
 	int			level,
 	void			*data)
 {
-	xfs_extlen_t		*blocks = data;
+	xfs_filblks_t		*blocks = data;
 	(*blocks)++;
 
 	return 0;
@@ -5154,7 +5154,7 @@ xfs_btree_count_blocks_helper(
 int
 xfs_btree_count_blocks(
 	struct xfs_btree_cur	*cur,
-	xfs_extlen_t		*blocks)
+	xfs_filblks_t		*blocks)
 {
 	*blocks = 0;
 	return xfs_btree_visit_blocks(cur, xfs_btree_count_blocks_helper,
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 3b739459ebb0..c5bff273cae2 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -484,7 +484,7 @@ typedef int (*xfs_btree_visit_blocks_fn)(struct xfs_btree_cur *cur, int level,
 int xfs_btree_visit_blocks(struct xfs_btree_cur *cur,
 		xfs_btree_visit_blocks_fn fn, unsigned int flags, void *data);
 
-int xfs_btree_count_blocks(struct xfs_btree_cur *cur, xfs_extlen_t *blocks);
+int xfs_btree_count_blocks(struct xfs_btree_cur *cur, xfs_filblks_t *blocks);
 
 union xfs_btree_rec *xfs_btree_rec_addr(struct xfs_btree_cur *cur, int n,
 		struct xfs_btree_block *block);
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index 9b34896dd1a3..6f270d8f4270 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -744,6 +744,7 @@ xfs_finobt_count_blocks(
 {
 	struct xfs_buf		*agbp = NULL;
 	struct xfs_btree_cur	*cur;
+	xfs_filblks_t		blocks;
 	int			error;
 
 	error = xfs_ialloc_read_agi(pag, tp, 0, &agbp);
@@ -751,9 +752,10 @@ xfs_finobt_count_blocks(
 		return error;
 
 	cur = xfs_finobt_init_cursor(pag, tp, agbp);
-	error = xfs_btree_count_blocks(cur, tree_blocks);
+	error = xfs_btree_count_blocks(cur, &blocks);
 	xfs_btree_del_cursor(cur, error);
 	xfs_trans_brelse(tp, agbp);
+	*tree_blocks = blocks;
 
 	return error;
 }