From 46d62d4ef2fba354a72f685bbfdab381d1dbe61d Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Sun, 20 Oct 2024 01:23:41 +0900 Subject: [PATCH 18/21] dax: Allow block size > PAGE_SIZE For virtio-dax, the file/FS blocksize is irrelevant. FUSE always uses large DAX blocks (2MiB), which will work with all host page sizes. Since we are mapping files into the DAX window on the host, the underlying block size of the filesystem and its block device (if any) are meaningless. For real devices with DAX, the only requirement should be that the FS block size is *at least* as large as PAGE_SIZE, to ensure that at least whole pages can be mapped out of the device contiguously. Fixes warning when using virtio-dax on a 4K guest with a 16K host, backed by tmpfs (which sets blksz == PAGE_SIZE on the host). Signed-off-by: Asahi Lina --- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 21b47402b3dc..b0950164d8ee 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1032,7 +1032,7 @@ int dax_writeback_mapping_range(struct address_space *mapping, int ret = 0; unsigned int scanned = 0; - if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) + if (WARN_ON_ONCE(inode->i_blkbits < PAGE_SHIFT)) return -EIO; if (mapping_empty(mapping) || wbc->sync_mode != WB_SYNC_ALL) -- 2.47.1