xfs: sparse inode chunks feature helpers and mount requirements

The sparse inode chunks feature uses the helper function to enable the
allocation of sparse inode chunks. The incompatible feature bit is set
on disk at mkfs time to prevent mount from unsupported kernels.

Also, enforce the inode alignment requirements required for sparse inode
chunks at mount time. When enabled, full inode chunks (and all inode
record) alignment is increased from cluster size to inode chunk size.
Sparse inode alignment must match the cluster size of the fs. Both
superblock alignment fields are set as such by mkfs when sparse inode
support is enabled.

Finally, warn that sparse inode chunks is an experimental feature until
further notice.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index 20acbc4450f8e0ada57480440415daa38c0ed346..f5b349965a99558cceeb1f6c4668be33249ea7ca 100644 (file)
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -457,6 +457,7 @@ xfs_sb_has_ro_compat_feature(
 }
 
 #define XFS_SB_FEAT_INCOMPAT_FTYPE     (1 << 0)        /* filetype in dirent */
+#define XFS_SB_FEAT_INCOMPAT_SPINODES  (1 << 1)        /* sparse inode chunks */
 #define XFS_SB_FEAT_INCOMPAT_ALL \
                (XFS_SB_FEAT_INCOMPAT_FTYPE)
 
@@ -506,6 +507,12 @@ static inline int xfs_sb_version_hasfinobt(xfs_sb_t *sbp)
                (sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_FINOBT);
 }
 
+static inline bool xfs_sb_version_hassparseinodes(struct xfs_sb *sbp)
+{
+       return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
+               xfs_sb_has_incompat_feature(sbp, XFS_SB_FEAT_INCOMPAT_SPINODES);
+}
+
 /*
  * end of superblock version macros
  */

diff --git a/libxfs/xfs_sb.c b/libxfs/xfs_sb.c
index fe16e8fdd57340bf962e0c764bfcd6ea9691f850..fcda8562102463b788cee6d857669cfbdc830e5e 100644 (file)
--- a/libxfs/xfs_sb.c
+++ b/libxfs/xfs_sb.c
@@ -172,6 +172,27 @@ xfs_mount_validate_sb(
                        return -EFSCORRUPTED;
        }
 
+       /*
+        * Full inode chunks must be aligned to inode chunk size when
+        * sparse inodes are enabled to support the sparse chunk
+        * allocation algorithm and prevent overlapping inode records.
+        */
+       if (xfs_sb_version_hassparseinodes(sbp)) {
+               uint32_t        align;
+
+               xfs_alert(mp,
+       "EXPERIMENTAL sparse inode feature enabled. Use at your own risk!");
+
+               align = XFS_INODES_PER_CHUNK * sbp->sb_inodesize
+                               >> sbp->sb_blocklog;
+               if (sbp->sb_inoalignmt != align) {
+                       xfs_warn(mp,
+"Inode block alignment (%u) must match chunk size (%u) for sparse inodes.",
+                                sbp->sb_inoalignmt, align);
+                       return -EINVAL;
+               }
+       }
+
        if (unlikely(
            sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {
                xfs_warn(mp,