Commit 7c71ee78 authored by Eric Sandeen's avatar Eric Sandeen Committed by Ben Myers
Browse files

xfs: allow logical-sector sized O_DIRECT 



Some time ago, mkfs.xfs started picking the storage physical
sector size as the default filesystem "sector size" in order
to avoid RMW costs incurred by doing IOs at logical sector
size alignments.

However, this means that for a filesystem made with i.e.
a 4k sector size on an "advanced format" 4k/512 disk,
512-byte direct IOs are no longer allowed.  This means
that XFS has essentially turned this AF drive into a hard
4K device, from the filesystem on up.

XFS's mkfs-specified "sector size" is really just controlling
the minimum size & alignment of filesystem metadata.

There is no real need to tightly couple XFS's minimal
metadata size to the minimum allowed direct IO size;
XFS can continue doing metadata in optimal sizes, but
still allow smaller DIOs for apps which issue them,
for whatever reason.

This patch adds a new field to the xfs_buftarg, so that
we now track 2 sizes:

 1) The metadata sector size, which is the minimum unit and
    alignment of IO which will be performed by metadata operations.
 2) The device logical sector size

The first is used internally by the file system for metadata
alignment and IOs.
The second is used for the minimum allowed direct IO alignment.

This has passed xfstests on filesystems made with 4k sectors,
including when run under the patch I sent to ignore
XFS_IOC_DIOINFO, and issue 512 DIOs anyway.  I also directly
tested end of block behavior on preallocated, sparse, and
existing files when we do a 512 IO into a 4k file on a 
4k-sector filesystem, to be sure there were no unexpected
behaviors.

Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent 6da54179

fs/xfs/xfs_buf.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -1599,6 +1599,7 @@ xfs_setsize_buftarg( 
	unsigned int		blocksize,

	unsigned int		blocksize,

	unsigned int		sectorsize)

	unsigned int		sectorsize)

{

{

	/* Set up metadata sector size info */

	btp->bt_meta_sectorsize = sectorsize;

	btp->bt_meta_sectorsize = sectorsize;

	btp->bt_meta_sectormask = sectorsize - 1;

	btp->bt_meta_sectormask = sectorsize - 1;
@@ -1613,6 +1614,10 @@ xfs_setsize_buftarg( 
		return EINVAL;

		return EINVAL;

	}

	}





	/* Set up device logical sector size mask */

	btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);

	btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;



	return 0;

	return 0;

}

}

fs/xfs/xfs_buf.h

+15 −0
Original line number Original line Diff line number Diff line
@@ -88,6 +88,19 @@ typedef unsigned int xfs_buf_flags_t; 
 */

 */

#define XFS_BSTATE_DISPOSE	 (1 << 0)	/* buffer being discarded */

#define XFS_BSTATE_DISPOSE	 (1 << 0)	/* buffer being discarded */





/*

 * The xfs_buftarg contains 2 notions of "sector size" -

 *

 * 1) The metadata sector size, which is the minimum unit and

 *    alignment of IO which will be performed by metadata operations.

 * 2) The device logical sector size

 *

 * The first is specified at mkfs time, and is stored on-disk in the

 * superblock's sb_sectsize.

 *

 * The latter is derived from the underlying device, and controls direct IO

 * alignment constraints.

 */

typedef struct xfs_buftarg {

typedef struct xfs_buftarg {

	dev_t			bt_dev;

	dev_t			bt_dev;

	struct block_device	*bt_bdev;

	struct block_device	*bt_bdev;
@@ -95,6 +108,8 @@ typedef struct xfs_buftarg { 
	struct xfs_mount	*bt_mount;

	struct xfs_mount	*bt_mount;

	unsigned int		bt_meta_sectorsize;

	unsigned int		bt_meta_sectorsize;

	size_t			bt_meta_sectormask;

	size_t			bt_meta_sectormask;

	size_t			bt_logical_sectorsize;

	size_t			bt_logical_sectormask;





	/* LRU control structures */

	/* LRU control structures */

	struct shrinker		bt_shrinker;

	struct shrinker		bt_shrinker;

fs/xfs/xfs_file.c

+5 −2
Original line number Original line Diff line number Diff line
@@ -261,7 +261,8 @@ xfs_file_aio_read( 
		xfs_buftarg_t	*target =

		xfs_buftarg_t	*target =

			XFS_IS_REALTIME_INODE(ip) ?

			XFS_IS_REALTIME_INODE(ip) ?

				mp->m_rtdev_targp : mp->m_ddev_targp;

				mp->m_rtdev_targp : mp->m_ddev_targp;

		if ((pos | size) & target->bt_meta_sectormask) {

		/* DIO must be aligned to device logical sector size */

		if ((pos | size) & target->bt_logical_sectormask) {

			if (pos == i_size_read(inode))

			if (pos == i_size_read(inode))

				return 0;

				return 0;

			return -XFS_ERROR(EINVAL);

			return -XFS_ERROR(EINVAL);
@@ -641,9 +642,11 @@ xfs_file_dio_aio_write( 
	struct xfs_buftarg	*target = XFS_IS_REALTIME_INODE(ip) ?

	struct xfs_buftarg	*target = XFS_IS_REALTIME_INODE(ip) ?

					mp->m_rtdev_targp : mp->m_ddev_targp;

					mp->m_rtdev_targp : mp->m_ddev_targp;





	if ((pos | count) & target->bt_meta_sectormask)

	/* DIO must be aligned to device logical sector size */

	if ((pos | count) & target->bt_logical_sectormask)

		return -XFS_ERROR(EINVAL);

		return -XFS_ERROR(EINVAL);





	/* "unaligned" here means not aligned to a filesystem block */

	if ((pos & mp->m_blockmask) || ((pos + count) & mp->m_blockmask))

	if ((pos & mp->m_blockmask) || ((pos + count) & mp->m_blockmask))

		unaligned_io = 1;

		unaligned_io = 1;

fs/xfs/xfs_ioctl.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -1583,7 +1583,7 @@ xfs_file_ioctl( 
			XFS_IS_REALTIME_INODE(ip) ?

			XFS_IS_REALTIME_INODE(ip) ?

			mp->m_rtdev_targp : mp->m_ddev_targp;

			mp->m_rtdev_targp : mp->m_ddev_targp;





		da.d_mem = da.d_miniosz = target->bt_meta_sectorsize;

		da.d_mem =  da.d_miniosz = target->bt_logical_sectorsize;

		da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1);

		da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1);





		if (copy_to_user(arg, &da, sizeof(da)))

		if (copy_to_user(arg, &da, sizeof(da)))

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