Commit 1f0d4ab0 authored by Mike Snitzer's avatar Mike Snitzer Committed by Anna Schumaker
Browse files

NFS: add basic STATX_DIOALIGN and STATX_DIO_READ_ALIGN support 



NFS doesn't have DIO alignment constraints, so have NFS respond with
accommodating DIO alignment attributes (rather than plumb in GETATTR
support for STATX_DIOALIGN and STATX_DIO_READ_ALIGN).

The most coarse-grained dio_offset_align is the most accommodating
(e.g. PAGE_SIZE, in future larger may be supported).

Now that NFS has support, NFS reexport will now handle unaligned DIO
(NFSD's NFSD_IO_DIRECT support requires the underlying filesystem
support STATX_DIOALIGN and/or STATX_DIO_READ_ALIGN).

Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
Signed-off-by: default avatarAnna Schumaker <anna.schumaker@oracle.com>
parent cda94457

fs/nfs/inode.c

+15 −0
Original line number Diff line number Diff line
@@ -1073,6 +1073,21 @@ int nfs_getattr(struct mnt_idmap *idmap, const struct path *path, 
	if (S_ISDIR(inode->i_mode))

		stat->blksize = NFS_SERVER(inode)->dtsize;

	stat->btime = NFS_I(inode)->btime;



	/* Special handling for STATX_DIOALIGN and STATX_DIO_READ_ALIGN

	 * - NFS doesn't have DIO alignment constraints, avoid getting

	 *   these DIO attrs from remote and just respond with most

	 *   accommodating limits (so client will issue supported DIO).

	 * - this is unintuitive, but the most coarse-grained

	 *   dio_offset_align is the most accommodating.

	 */

	if ((request_mask & (STATX_DIOALIGN | STATX_DIO_READ_ALIGN)) &&

	    S_ISREG(inode->i_mode)) {

		stat->result_mask |= STATX_DIOALIGN | STATX_DIO_READ_ALIGN;

		stat->dio_mem_align = 4; /* 4-byte alignment */

		stat->dio_offset_align = PAGE_SIZE;

		stat->dio_read_offset_align = stat->dio_offset_align;

	}

out:

	trace_nfs_getattr_exit(inode, err);

	return err;