Commit 87eefeb4 authored May 10, 2016 by Toshi Kani Committed by Vishal Verma May 17, 2016

ext4: Add alignment check for DAX mount



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_dax_supported() to perform proper precondition checks
which includes this partition alignment check.

Reported-by: Micah Parrish <micah.parrish@hpe.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

parent 2d96afc8

fs/ext4/super.c

+2 −9

Original line number	Diff line number	Diff line
		@@ -3417,17 +3417,10 @@ 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_dax_supported(sb, blocksize);
		if (err)
		goto failed_mount;
		}
		}

		if (ext4_has_feature_encrypt(sb) && es->s_encryption_level) {
		ext4_msg(sb, KERN_ERR, "Unsupported encryption level %d",

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