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[1/5] dax: Add block size note to documentation

Message ID 1435608152-6982-2-git-send-email-matthew.r.wilcox@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Wilcox, Matthew R June 29, 2015, 8:02 p.m. UTC 
From: Matthew Wilcox <willy@linux.intel.com>

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 <willy@linux.intel.com>
---
 Documentation/filesystems/dax.txt | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
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Patch

diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt
index baf4111..7af2851 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