[PATCH v11 08/15] xfs: Report case sensitivity in fileattr_get

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

Upper layers such as NFSD need to query whether a filesystem
is case-sensitive. Add FS_XFLAG_CASEFOLD to xfs_ip2xflags()
when the filesystem is formatted with the ASCIICI feature
flag. This serves both FS_IOC_FSGETXATTR (via xfs_fill_fsxattr() in
xfs_fileattr_get()) and XFS_IOC_BULKSTAT (which populates bs_xflags
directly from xfs_ip2xflags()), so bulkstat consumers and per-inode
queries see a consistent view of the filesystem's case-folding
behavior.

XFS always preserves case. XFS is case-sensitive by default, but
supports ASCII case-insensitive lookups when formatted with the
ASCIICI feature flag.

Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/xfs/libxfs/xfs_inode_util.c | 2 ++
 fs/xfs/xfs_ioctl.c             | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_inode_util.c b/fs/xfs/libxfs/xfs_inode_util.c
index 551fa51befb6..82be54b6f8d3 100644
--- a/fs/xfs/libxfs/xfs_inode_util.c
+++ b/fs/xfs/libxfs/xfs_inode_util.c
@@ -130,6 +130,8 @@ xfs_ip2xflags(
 
 	if (xfs_inode_has_attr_fork(ip))
 		flags |= FS_XFLAG_HASATTR;
+	if (xfs_has_asciici(ip->i_mount))
+		flags |= FS_XFLAG_CASEFOLD;
 	return flags;
 }
 
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index ed9b4846c05f..5a58fb0bad2b 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -472,6 +472,13 @@ xfs_fill_fsxattr(
 
 	fileattr_fill_xflags(fa, xfs_ip2xflags(ip));
 
+	/*
+	 * FS_XFLAG_CASEFOLD is read-only; hide it from the legacy
+	 * flags view so chattr's RMW cycle does not pass it back to
+	 * xfs_fileattr_set().
+	 */
+	fa->flags &= ~FS_CASEFOLD_FL;
+
 	if (ip->i_diflags & XFS_DIFLAG_EXTSIZE) {
 		fa->fsx_extsize = XFS_FSB_TO_B(mp, ip->i_extsize);
 	} else if (ip->i_diflags & XFS_DIFLAG_EXTSZINHERIT) {

-- 
2.53.0