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 <[email protected]> Signed-off-by: Toshi Kani <[email protected]> Cc: "Theodore Ts'o" <[email protected]> Cc: Andreas Dilger <[email protected]> Cc: Jan Kara <[email protected]> Cc: Dan Williams <[email protected]> Cc: Ross Zwisler <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Boaz Harrosh <[email protected]> --- 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; } }
