fs/ext4: Make DAX mount option a tri-state

We add 'always', 'never', and 'inode' (default).  '-o dax' continues to
operate the same which is equivalent to 'always'.  This new
functionality is limited to ext4 only.

Specifically we introduce a 2nd DAX mount flag EXT4_MOUNT2_DAX_NEVER and set
it and EXT4_MOUNT_DAX_ALWAYS appropriately for the mode.

We also force EXT4_MOUNT2_DAX_NEVER if !CONFIG_FS_DAX.

Finally, EXT4_MOUNT2_DAX_INODE is used solely to detect if the user
specified that option for printing.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

Link: https://lore.kernel.org/r/20200528150003.828793-7-ira.weiny@intel.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Ira Weiny
2020-05-28 08:00:00 -07:00
committed by Theodore Ts'o
parent 043546e46d
commit 9cb20f94af
3 changed files with 61 additions and 10 deletions

View File

@@ -1168,6 +1168,8 @@ struct ext4_inode_info {
blocks */
#define EXT4_MOUNT2_HURD_COMPAT 0x00000004 /* Support HURD-castrated
file systems */
#define EXT4_MOUNT2_DAX_NEVER 0x00000008 /* Do not allow Direct Access */
#define EXT4_MOUNT2_DAX_INODE 0x00000010 /* For printing options only */
#define EXT4_MOUNT2_EXPLICIT_JOURNAL_CHECKSUM 0x00000008 /* User explicitly
specified journal checksum */