[PATCH v3 12/18] xfs: filter out sparse regions from individual inode allocation

Brian Foster
2015-02-06T19:53:08Z

Inode allocation from an existing record with free inodes traditionally
selects the first inode available according to the ir_free mask. With
sparse inode chunks, the ir_free mask could refer to an unallocated
region. We must mask the unallocated regions out of ir_free before using
it to select a free inode in the chunk.

Create the xfs_inobt_first_free_inode() helper to find the first free
inode available of the allocated regions of the inode chunk.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
fs/xfs/libxfs/xfs_ialloc.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 3e5d3eb..2691d3e 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -1183,6 +1183,30 @@ xfs_inobt_ialloc_bitmap(
}

/*
+ * Return the offset of the first free inode in the record. If the inode chunk
+ * is sparsely allocated, we convert the record holemask to inode granularity
+ * and mask off the unallocated regions from the inode free mask.
+ */
+STATIC int
+xfs_inobt_first_free_inode(
+ struct xfs_inobt_rec_incore *rec)
+{
+ xfs_inofree_t realfree;
+ DECLARE_BITMAP(alloc, 64);
+
+ /* if there are no holes, return the first available offset */
+ if (!xfs_inobt_issparse(rec->ir_holemask))
+ return xfs_lowbit64(rec->ir_free);
+
+ xfs_inobt_ialloc_bitmap(alloc, rec);
+ realfree = bitmap_to_u64(alloc, 64);
+
+ realfree &= rec->ir_free;
+
+ return xfs_lowbit64(realfree);
+}
+
+/*
* Allocate an inode using the inobt-only algorithm.
*/
STATIC int
@@ -1412,7 +1436,7 @@ newino:
}

alloc_inode:
- offset = xfs_lowbit64(rec.ir_free);
+ offset = xfs_inobt_first_free_inode(&rec);
ASSERT(offset >= 0);
ASSERT(offset < XFS_INODES_PER_CHUNK);
ASSERT((XFS_AGINO_TO_OFFSET(mp, rec.ir_startino) %
@@ -1661,7 +1685,7 @@ xfs_dialloc_ag(
if (error)
goto error_cur;

- offset = xfs_lowbit64(rec.ir_free);
+ offset = xfs_inobt_first_free_inode(&rec);
ASSERT(offset >= 0);
ASSERT(offset < XFS_INODES_PER_CHUNK);
ASSERT((XFS_AGINO_TO_OFFSET(mp, rec.ir_startino) %
--
1.8.3.1