[PATCH 9/9] xfs: allow bulkstat_single of special inodes

Darrick J. Wong
2019-05-29T22:29:29Z

From: Darrick J. Wong <darrick.wong@oracle.com>

Create a new ireq flag (for single bulkstats) that enables userspace to
ask us for a special inode number instead of interpreting @ino as a
literal inode number. This enables us to query the root inode easily.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/libxfs/xfs_fs.h | 11 ++++++++++-
fs/xfs/xfs_ioctl.c | 10 ++++++++++
2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index 77c06850ac52..1826aa11b585 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -482,7 +482,16 @@ struct xfs_ireq {
uint64_t reserved[2]; /* must be zero */
};

-#define XFS_IREQ_FLAGS_ALL (0)
+/*
+ * The @ino value is a special value, not a literal inode number. See the
+ * XFS_IREQ_SPECIAL_* values below.
+ */
+#define XFS_IREQ_SPECIAL (1 << 0)
+
+#define XFS_IREQ_FLAGS_ALL (XFS_IREQ_SPECIAL)
+
+/* Return the root directory inode. */
+#define XFS_IREQ_SPECIAL_ROOT (1)

/*
* ioctl structures for v5 bulkstat and inumbers requests
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index cf48a2bad325..605bfff3011f 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -959,6 +959,16 @@ xfs_ireq_setup(
memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
return -EINVAL;

+ if (hdr->flags & XFS_IREQ_SPECIAL) {
+ switch (hdr->ino) {
+ case XFS_IREQ_SPECIAL_ROOT:
+ hdr->ino = mp->m_sb.sb_rootino;
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+
if (XFS_INO_TO_AGNO(mp, hdr->ino) >= mp->m_sb.sb_agcount)
return -EINVAL;