From 44f4c054cae646a9296da05cdfe7d6e786f73d46 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 3 Jul 2015 10:40:38 -0400 Subject: [PATCH] dax: Add block size note to documentation For block devices which are small enough, mkfs will default to creating a filesystem with block sizes smaller than page size. Signed-off-by: Matthew Wilcox Signed-off-by: Al Viro --- Documentation/filesystems/dax.txt | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt index baf41118660d..7af2851d667c 100644 --- a/Documentation/filesystems/dax.txt +++ b/Documentation/filesystems/dax.txt @@ -18,8 +18,10 @@ Usage ----- If you have a block device which supports DAX, you can make a filesystem -on it as usual. When mounting it, use the -o dax option manually -or add 'dax' to the options in /etc/fstab. +on it as usual. The DAX code currently only supports files with a block +size equal to your kernel's PAGE_SIZE, so you may need to specify a block +size when creating the filesystem. When mounting it, use the "-o dax" +option on the command line or add 'dax' to the options in /etc/fstab. Implementation Tips for Block Driver Writers -- 2.20.1