[RFC 22/23] xfs: enable block size larger than page size support

[Pankaj Raghav <kernel@pankajraghav.com>]

From: Pankaj Raghav <p.raghav@samsung.com>

Currently we don't support blocksize that is twice the page size due to
the limitation of having at least three pages in a large folio[1].

[1] https://lore.kernel.org/all/ZH0GvxAdw1RO2Shr@casper.infradead.org/

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 fs/xfs/xfs_mount.c | 9 +++++++--
 fs/xfs/xfs_super.c | 7 ++-----
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index aed5be5508fe..4272898c508a 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -131,11 +131,16 @@ xfs_sb_validate_fsb_count(
 	xfs_sb_t	*sbp,
 	uint64_t	nblocks)
 {
-	ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
 	ASSERT(sbp->sb_blocklog >= BBSHIFT);
+	unsigned long mapping_count;
+
+	if (sbp->sb_blocklog <= PAGE_SHIFT)
+		mapping_count = nblocks >> (PAGE_SHIFT - sbp->sb_blocklog);
+	else
+		mapping_count = nblocks << (sbp->sb_blocklog - PAGE_SHIFT);
 
 	/* Limited by ULONG_MAX of page cache index */
-	if (nblocks >> (PAGE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
+	if (mapping_count > ULONG_MAX)
 		return -EFBIG;
 	return 0;
 }
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 1f77014c6e1a..75bf4d23051c 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1651,13 +1651,10 @@ xfs_fs_fill_super(
 		goto out_free_sb;
 	}
 
-	/*
-	 * Until this is fixed only page-sized or smaller data blocks work.
-	 */
-	if (mp->m_sb.sb_blocksize > PAGE_SIZE) {
+	if (mp->m_sb.sb_blocksize == (2 * PAGE_SIZE)) {
 		xfs_warn(mp,
 		"File system with blocksize %d bytes. "
-		"Only pagesize (%ld) or less will currently work.",
+		"Blocksize that is twice the pagesize %ld does not currently work.",
 				mp->m_sb.sb_blocksize, PAGE_SIZE);
 		error = -ENOSYS;
 		goto out_free_sb;
-- 
2.40.1