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>
---
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;
}
}
--
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