[05/22] xfs: make XFS_DQUOT_CLUSTER_SIZE_FSB part of the ondisk format
diff mbox series

Message ID 159398718628.425236.8654425233877130537.stgit@magnolia
State Superseded
Headers show
Series
  • xfs: remove xfs_disk_quot from incore dquot
Related show

Commit Message

Darrick J. Wong July 5, 2020, 10:13 p.m. UTC
From: Darrick J. Wong <darrick.wong@oracle.com>

Move the dquot cluster size #define to xfs_format.h.  It is an important
part of the ondisk format because the ondisk dquot record size is not an
even power of two, which means that the buffer size we use is
significant here because the kernel leaves slack space at the end of the
buffer to avoid having to deal with a dquot record crossing a block
boundary.

This is also an excuse to fix one of the longstanding discrepancies
between kernel and userspace libxfs headers.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_format.h |   16 ++++++++++++++++
 fs/xfs/xfs_qm.h            |   11 -----------
 2 files changed, 16 insertions(+), 11 deletions(-)

Comments

Christoph Hellwig July 9, 2020, 1:47 p.m. UTC | #1
On Sun, Jul 05, 2020 at 03:13:06PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Move the dquot cluster size #define to xfs_format.h.  It is an important
> part of the ondisk format because the ondisk dquot record size is not an
> even power of two, which means that the buffer size we use is
> significant here because the kernel leaves slack space at the end of the
> buffer to avoid having to deal with a dquot record crossing a block
> boundary.
> 
> This is also an excuse to fix one of the longstanding discrepancies
> between kernel and userspace libxfs headers.

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Patch
diff mbox series

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index fcd270194e47..d6615103db0c 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -1209,6 +1209,22 @@  typedef struct xfs_dqblk {
 
 #define XFS_DQUOT_CRC_OFF	offsetof(struct xfs_dqblk, dd_crc)
 
+/*
+ * This defines the unit of allocation of dquots.
+ *
+ * Currently, it is just one file system block, and a 4K blk contains 30
+ * (136 * 30 = 4080) dquots. It's probably not worth trying to make
+ * this more dynamic.
+ *
+ * However, if this number is changed, we have to make sure that we don't
+ * implicitly assume that we do allocations in chunks of a single filesystem
+ * block in the dquot/xqm code.
+ *
+ * This is part of the ondisk format because the structure size is not a power
+ * of two, which leaves slack at the end of the disk block.
+ */
+#define XFS_DQUOT_CLUSTER_SIZE_FSB	(xfs_filblks_t)1
+
 /*
  * Remote symlink format and access functions.
  */
diff --git a/fs/xfs/xfs_qm.h b/fs/xfs/xfs_qm.h
index 7b0e771fcbce..2c8ca9df23af 100644
--- a/fs/xfs/xfs_qm.h
+++ b/fs/xfs/xfs_qm.h
@@ -30,17 +30,6 @@  extern struct kmem_zone	*xfs_qm_dqtrxzone;
 	!dqp->q_core.d_rtbcount && \
 	!dqp->q_core.d_icount)
 
-/*
- * This defines the unit of allocation of dquots.
- * Currently, it is just one file system block, and a 4K blk contains 30
- * (136 * 30 = 4080) dquots. It's probably not worth trying to make
- * this more dynamic.
- * XXXsup However, if this number is changed, we have to make sure that we don't
- * implicitly assume that we do allocations in chunks of a single filesystem
- * block in the dquot/xqm code.
- */
-#define XFS_DQUOT_CLUSTER_SIZE_FSB	(xfs_filblks_t)1
-
 /* Defaults for each quota type: time limits, warn limits, usage limits */
 struct xfs_def_quota {
 	time64_t	btimelimit;	/* limit for blks timer */