On Mon 02-05-16 12:42:56, Toshi Kani wrote:
> When a partition is not aligned by 4KB, mount -o dax succeeds,
> but any read/write access to the filesystem fails, except for
> metadata update.
>
> Call bdev_direct_access to check the alignment when -o dax is
> specified.
>
> Reported-by: Micah Parrish <micah.parrish@xxxxxxx>
> Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
> Cc: "Theodore Ts'o" <tytso@xxxxxxx>
> Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Cc: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/ext4/super.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 304c712..51ac78e 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3416,14 +3416,30 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> }
>
> if (sbi->s_mount_opt & EXT4_MOUNT_DAX) {
> + struct blk_dax_ctl dax = {
> + .sector = 0,
> + .size = PAGE_SIZE,
> + };
> if (blocksize != PAGE_SIZE) {
> ext4_msg(sb, KERN_ERR,
> "error: unsupported blocksize for dax");
> goto failed_mount;
> }
> - if (!sb->s_bdev->bd_disk->fops->direct_access) {
> - ext4_msg(sb, KERN_ERR,
> + err = bdev_direct_access(sb->s_bdev, &dax);
> + if (err < 0) {
> + switch (err) {
> + case -EOPNOTSUPP:
> + ext4_msg(sb, KERN_ERR,
> "error: device does not support dax");
> + break;
> + case -EINVAL:
> + ext4_msg(sb, KERN_ERR,
> + "error: unaligned partition for dax");
> + break;
> + default:
> + ext4_msg(sb, KERN_ERR,
> + "error: dax access failed (%d)", err);
> + }
> goto failed_mount;
> }
> }
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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