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_supports_dax() to perform proper precondition checks which includes this partition alignment check. 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 | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 304c712..e7ca71c 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3416,16 +3416,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } if (sbi->s_mount_opt & EXT4_MOUNT_DAX) { - 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, - "error: device does not support dax"); + err = bdev_supports_dax(sb, blocksize); + if (err) goto failed_mount; - } } if (ext4_has_feature_encrypt(sb) && es->s_encryption_level) {
