On 28 Sep 2021 at 04:36, Dave Chinner wrote:

On Thu, Sep 16, 2021 at 03:36:44PM +0530, Chandan Babu R wrote:

quoted

The following changes are made to enable userspace to obtain 64-bit extent
counters,
1. To hold 64-bit extent counters, carve out the new 64-bit field
   xfs_bulkstat->bs_extents64 from xfs_bulkstat->bs_pad[].
2. Carve out a new 64-bit field xfs_bulk_ireq->bulkstat_flags from
   xfs_bulk_ireq->reserved[] to hold bulkstat specific operational flags.  As of
   this commit, XFS_IBULK_NREXT64 is the only valid flag that this field can
   hold. It indicates that userspace has the necessary infrastructure to
   receive 64-bit extent counters.
3. Define the new flag XFS_BULK_IREQ_BULKSTAT for userspace to indicate that
   xfs_bulk_ireq->bulkstat_flags has valid flags set.

This seems unnecessarily complex. It adds a new flag to define a new
flag field in the same structure and then define a new and a new
flag in the new flag field to define a new behaviour.

Why can't this be done with just a single new flag in the existing
flags field?

Yes, This can be implemented with just one flag. I will make the relevant
changes before posting the next version.

quoted

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <redacted>
---
 fs/xfs/libxfs/xfs_fs.h | 19 ++++++++++++++-----
 fs/xfs/xfs_ioctl.c     |  7 +++++++
 fs/xfs/xfs_itable.c    | 25 +++++++++++++++++++++++--
 fs/xfs/xfs_itable.h    |  2 ++
 fs/xfs/xfs_iwalk.h     |  7 +++++--
 5 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index 2594fb647384..b76906914d89 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h

@@ -394,7 +394,7 @@ struct xfs_bulkstat {
 	uint32_t	bs_extsize_blks; /* extent size hint, blocks	*/
 
 	uint32_t	bs_nlink;	/* number of links		*/
-	uint32_t	bs_extents;	/* number of extents		*/
+	uint32_t	bs_extents32;	/* 32-bit data fork extent counter */
 	uint32_t	bs_aextents;	/* attribute number of extents	*/
 	uint16_t	bs_version;	/* structure version		*/
 	uint16_t	bs_forkoff;	/* inode fork offset in bytes	*/

I don't think renaming structure members is a good idea - it breaks
the user API and forces applications to require source level
modifications just to compile on both old and new xfsprogs installs.

Ok. I will revert the rename.

quoted

@@ -403,8 +403,9 @@ struct xfs_bulkstat {
 	uint16_t	bs_checked;	/* checked inode metadata	*/
 	uint16_t	bs_mode;	/* type and mode		*/
 	uint16_t	bs_pad2;	/* zeroed			*/
+	uint64_t	bs_extents64;	/* 64-bit data fork extent counter */
 
-	uint64_t	bs_pad[7];	/* zeroed			*/
+	uint64_t	bs_pad[6];	/* zeroed			*/
 };
 
 #define XFS_BULKSTAT_VERSION_V1	(1)

@@ -469,7 +470,8 @@ struct xfs_bulk_ireq {
 	uint32_t	icount;		/* I: count of entries in buffer */
 	uint32_t	ocount;		/* O: count of entries filled out */
 	uint32_t	agno;		/* I: see comment for IREQ_AGNO	*/
-	uint64_t	reserved[5];	/* must be zero			*/
+	uint64_t	bulkstat_flags; /* I: Bulkstat operation flags */
+	uint64_t	reserved[4];	/* must be zero			*/
 };
 
 /*

@@ -492,9 +494,16 @@ struct xfs_bulk_ireq {
  */
 #define XFS_BULK_IREQ_METADIR	(1 << 2)
 
-#define XFS_BULK_IREQ_FLAGS_ALL	(XFS_BULK_IREQ_AGNO | \
+#define XFS_BULK_IREQ_BULKSTAT	(1 << 3)
+
+#define XFS_BULK_IREQ_FLAGS_ALL	(XFS_BULK_IREQ_AGNO |	 \
 				 XFS_BULK_IREQ_SPECIAL | \
-				 XFS_BULK_IREQ_METADIR)
+				 XFS_BULK_IREQ_METADIR | \
+				 XFS_BULK_IREQ_BULKSTAT)

What's this XFS_BULK_IREQ_METADIR thing? I haven't noticed that when
scanning any recent proposed patch series....

XFS_BULK_IREQ_METADIR is from Darrick's tree. His "Kill XFS_BTREE_MAXLEVELS"
patch series is based on his other patchsets. His recent "xfs: support dynamic
btree cursor height" patch series rebases only the required patchset on top of
v5.15-rc1 kernel eliminating the others.

quoted

+#define XFS_BULK_IREQ_BULKSTAT_NREXT64 (1 << 0)
+
+#define XFS_BULK_IREQ_BULKSTAT_FLAGS_ALL (XFS_BULK_IREQ_BULKSTAT_NREXT64)

As per above, this seems unnecessarily complex.

quoted

@@ -134,7 +136,26 @@ xfs_bulkstat_one_int(
 
 	buf->bs_xflags = xfs_ip2xflags(ip);
 	buf->bs_extsize_blks = ip->i_extsize;
-	buf->bs_extents = xfs_ifork_nextents(&ip->i_df);
+
+	nextents = xfs_ifork_nextents(&ip->i_df);
+	if (!(bc->breq->flags & XFS_IBULK_NREXT64)) {
+		xfs_extnum_t max_nextents = XFS_IFORK_EXTCNT_MAXS32;
+
+		if (unlikely(XFS_TEST_ERROR(false, mp,
+				XFS_ERRTAG_REDUCE_MAX_IEXTENTS)))
+			max_nextents = 10;
+
+		if (nextents > max_nextents) {
+			xfs_iunlock(ip, XFS_ILOCK_SHARED);
+			xfs_irele(ip);
+			error = -EINVAL;
+			goto out_advance;
+		}

So we return an EINVAL error if any extent overflows the 32 bit
counter? Why isn't this -EOVERFLOW?

Returning -EINVAL causes xfs_bulkstat_iwalk() to skip inodes whose extent
count is larger than that which can be fitted into a 32-bit field. Returning
-EOVERFLOW causes the bulkstat ioctl to stop reporting remaining inodes.

quoted

+		buf->bs_extents32 = nextents;
+	} else {
+		buf->bs_extents64 = nextents;
+	}
+
 	xfs_bulkstat_health(ip, buf);
 	buf->bs_aextents = xfs_ifork_nextents(ip->i_afp);
 	buf->bs_forkoff = XFS_IFORK_BOFF(ip);

@@ -356,7 +377,7 @@ xfs_bulkstat_to_bstat(
 	bs1->bs_blocks = bstat->bs_blocks;
 	bs1->bs_xflags = bstat->bs_xflags;
 	bs1->bs_extsize = XFS_FSB_TO_B(mp, bstat->bs_extsize_blks);
-	bs1->bs_extents = bstat->bs_extents;
+	bs1->bs_extents = bstat->bs_extents32;
 	bs1->bs_gen = bstat->bs_gen;
 	bs1->bs_projid_lo = bstat->bs_projectid & 0xFFFF;
 	bs1->bs_forkoff = bstat->bs_forkoff;

diff --git a/fs/xfs/xfs_itable.h b/fs/xfs/xfs_itable.h
index f5a13f69883a..f61685da3837 100644
--- a/fs/xfs/xfs_itable.h
+++ b/fs/xfs/xfs_itable.h

@@ -22,6 +22,8 @@ struct xfs_ibulk {
 /* Signal that we can return metadata directories. */
 #define XFS_IBULK_METADIR	(XFS_IWALK_METADIR)
 
+#define XFS_IBULK_NREXT64	(XFS_IWALK_NREXT64)
+
 /*
  * Advance the user buffer pointer by one record of the given size.  If the
  * buffer is now full, return the appropriate error code.

diff --git a/fs/xfs/xfs_iwalk.h b/fs/xfs/xfs_iwalk.h
index d7a082e45cbf..27a6842a1bb5 100644
--- a/fs/xfs/xfs_iwalk.h
+++ b/fs/xfs/xfs_iwalk.h

@@ -31,8 +31,11 @@ int xfs_iwalk_threaded(struct xfs_mount *mp, xfs_ino_t startino,
 /* Signal that we can return metadata directories. */
 #define XFS_IWALK_METADIR	(0x2)
 
-#define XFS_IWALK_FLAGS_ALL	(XFS_IWALK_SAME_AG | \
-				 XFS_IWALK_METADIR)
+#define XFS_IWALK_NREXT64	(0x4)

Can we use '(1 << 2)' style notation for new bit field defines?

Sure, I will change this.

-- 
chandan