fs/ext4: Update ext4_should_use_dax()
S_DAX should only be enabled when the underlying block device supports
dax.
Cache the underlying support for DAX in the super block and modify
ext4_should_use_dax() to check for device support prior to the over
riding mount option.
While we are at it change the function to ext4_should_enable_dax() as
this better reflects the ask as well as matches xfs.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20200528150003.828793-5-ira.weiny@intel.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7b99c44..f7d76dc 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4092,13 +4092,16 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
goto failed_mount;
}
+ if (bdev_dax_supported(sb->s_bdev, blocksize))
+ set_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags);
+
if (sbi->s_mount_opt & EXT4_MOUNT_DAX_ALWAYS) {
if (ext4_has_feature_inline_data(sb)) {
ext4_msg(sb, KERN_ERR, "Cannot use DAX on a filesystem"
" that may contain inline data");
goto failed_mount;
}
- if (!bdev_dax_supported(sb->s_bdev, blocksize)) {
+ if (!test_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags)) {
ext4_msg(sb, KERN_ERR,
"DAX unsupported by block device.");
goto failed_mount;