[PATCH v3 05/18] xfs: create macros/helpers for dealing with sparse inode chunks

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

Sparse inode chunks allow the traditional inode btree record format to
describe an inode chunk that is not fully allocated and/or contiguous.
The granularity of a sparse chunk is defined by the the 16-bit holemask
field in the inode record. Assuming 64 inodes per full chunk, a single
holemask bit accounts for 4 inodes.

Define a constant for the number of inodes per holemask bit and a helper
function to easily detect sparse inode chunks.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
fs/xfs/libxfs/xfs_format.h | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 6c2f1be..b2faced 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -1285,6 +1285,10 @@ typedef __uint64_t xfs_inofree_t;
#define XFS_INOBT_ALL_FREE ((xfs_inofree_t)-1)
#define XFS_INOBT_MASK(i) ((xfs_inofree_t)1 << (i))

+#define XFS_INOBT_HOLEMASK_BITS (NBBY * sizeof(__uint16_t))
+#define XFS_INODES_PER_HOLEMASK_BIT \
+ (XFS_INODES_PER_CHUNK / (NBBY * sizeof(__uint16_t)))
+
static inline xfs_inofree_t xfs_inobt_maskn(int i, int n)
{
return ((n >= XFS_INODES_PER_CHUNK ? 0 : XFS_INOBT_MASK(n)) - 1) << i;
@@ -1309,6 +1313,11 @@ typedef struct xfs_inobt_rec_incore {
xfs_inofree_t ir_free; /* free inode mask */
} xfs_inobt_rec_incore_t;

+static inline bool xfs_inobt_issparse(uint16_t holemask)
+{
+ /* non-zero holemask represents a sparse rec. */
+ return holemask;
+}

/*
* Key structure
--
1.8.3.1