diff options
Diffstat (limited to 'kernel/Documentation/filesystems/dax.txt')
| -rw-r--r-- | kernel/Documentation/filesystems/dax.txt | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/kernel/Documentation/filesystems/dax.txt b/kernel/Documentation/filesystems/dax.txt index baf411186..7bde64014 100644 --- a/kernel/Documentation/filesystems/dax.txt +++ b/kernel/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 @@ -58,9 +60,10 @@ Filesystem support consists of - implementing the direct_IO address space operation, and calling dax_do_io() instead of blockdev_direct_IO() if S_DAX is set - implementing an mmap file operation for DAX files which sets the - VM_MIXEDMAP flag on the VMA, and setting the vm_ops to include handlers - for fault and page_mkwrite (which should probably call dax_fault() and - dax_mkwrite(), passing the appropriate get_block() callback) + VM_MIXEDMAP and VM_HUGEPAGE flags on the VMA, and setting the vm_ops to + include handlers for fault, pmd_fault and page_mkwrite (which should + probably call dax_fault(), dax_pmd_fault() and dax_mkwrite(), passing the + appropriate get_block() callback) - calling dax_truncate_page() instead of block_truncate_page() for DAX files - calling dax_zero_page_range() instead of zero_user() for DAX files - ensuring that there is sufficient locking between reads, writes, |