On 1/20/14, 8:21 AM, Brian Foster wrote:
> On 01/17/2014 03:28 PM, Eric Sandeen wrote:
>> 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 new information 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 size and
>> 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: Eric Sandeen <sandeen@xxxxxxxxxx>
>> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
>> index a526f8d..5175711 100644
>> --- a/fs/xfs/xfs_buf.c
>> +++ b/fs/xfs/xfs_buf.c
>> @@ -1599,6 +1599,7 @@ xfs_setsize_buftarg(
>> unsigned int blocksize,
>> unsigned int sectorsize)
>> {
>> + /* Set up metadata sector size info */
>> btp->bt_meta_sectorsize = sectorsize;
>> btp->bt_meta_sectormask = sectorsize - 1;
>>
>> @@ -1613,6 +1614,10 @@ xfs_setsize_buftarg(
>> 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;
>> }
>>
>> diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
>> index d5d88dd..9953395 100644
>> --- a/fs/xfs/xfs_buf.h
>> +++ b/fs/xfs/xfs_buf.h
>> @@ -88,6 +88,19 @@ typedef unsigned int xfs_buf_flags_t;
>> */
>> #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 {
>> dev_t bt_dev;
>> struct block_device *bt_bdev;
>> @@ -95,6 +108,8 @@ typedef struct xfs_buftarg {
>> struct xfs_mount *bt_mount;
>> unsigned int bt_meta_sectorsize;
>> size_t bt_meta_sectormask;
>> + size_t bt_logical_sectorsize;
>> + size_t bt_logical_sectormask;
>>
>> /* LRU control structures */
>> struct shrinker bt_shrinker;
>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
>> index 61a7de0..5507420 100644
>> --- a/fs/xfs/xfs_file.c
>> +++ b/fs/xfs/xfs_file.c
>> @@ -261,7 +261,8 @@ xfs_file_aio_read(
>> xfs_buftarg_t *target =
>> XFS_IS_REALTIME_INODE(ip) ?
>> 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))
>> return 0;
>> return -XFS_ERROR(EINVAL);
>> @@ -641,9 +642,11 @@ xfs_file_dio_aio_write(
>> struct xfs_buftarg *target = XFS_IS_REALTIME_INODE(ip) ?
>> 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);
>>
>
> Looks like this requires a v2 to preserve the fixes made in v2 of patch
> 2, unless I missed a newer version of this somewhere.
You're right. 2 diligence demerits for me. :(
(Hopefully it just wouldn't have applied...)
Maybe I'll just resend the whole series.
Thanks,
-Eric
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