Merge tag 'xtensa-next-20140224' of git://github.com/czankel/xtensa-linux

[~andy/linux] / fs / xfs / xfs_buf.h

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 1cf21a4a9f221de465299bf820fa710c3b3aa40e..995339534db6a4b65c6ec332055734f7415ca621 100644 (file)
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -88,14 +88,28 @@ 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;
        struct backing_dev_info *bt_bdi;
        struct xfs_mount        *bt_mount;
-       unsigned int            bt_bsize;
-       unsigned int            bt_sshift;
-       size_t                  bt_smask;
+       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;