9:35 a.m.
On 04/29/2016 11:39 PM, 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.
Add alignment check to ext4_fill_super() when -o dax is specified.
Reported-by: Micah Parrish <micah.parrish(a)hpe.com>
Signed-off-by: Toshi Kani <toshi.kani(a)hpe.com>
Cc: "Theodore Ts'o" <tytso(a)mit.edu>
Cc: Andreas Dilger <adilger.kernel(a)dilger.ca>
Cc: Jan Kara <jack(a)suse.cz>
Cc: Dan Williams <dan.j.williams(a)intel.com>
Cc: Ross Zwisler <ross.zwisler(a)linux.intel.com>
---
fs/ext4/super.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 304c712..90a8670 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3421,6 +3421,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int
silent)
"error: unsupported blocksize for dax");
goto failed_mount;
}
+ if (sb->s_bdev->bd_part->start_sect % (PAGE_SIZE / 512) ||
+ sb->s_bdev->bd_part->nr_sects % (PAGE_SIZE / 512)) {
Can you please not do this like this? For me is a layering violation only
the device should know what are its limits.
I would prefer if you just try to bdev_direct_access() the 0 sector and if
it fails then fail here. This way you let the device decide what it needs
and if/how to support unaligned partitions.
(For example it could by shrinking its size)
Thanks
Boaz
+ ext4_msg(sb, KERN_ERR,
+ "error: unaligned partition 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");
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