[PATCH 096/119] xfs: support FS_XFLAG_REFLINK on reflink filesystems

Darrick J. Wong
2016-06-17T01:28:21Z

Add support for reporting the "reflink" inode flag in the XFS-specific
getxflags ioctl, and allow the user to clear the flag if file size is
zero.

v2: Move the reflink flag out of the way of the DAX flag, and add the
new cowextsize flag.

v3: do not report (or allow changes to) FL_NOCOW_FL, since we don't
support a flag to prevent CoWing and the reflink flag is a poor
proxy. We'll try to design away the need for the NOCOW flag.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/xfs_inode.c | 2 ++
fs/xfs/xfs_ioctl.c | 4 ++++
fs/xfs/xfs_reflink.c | 26 ++++++++++++++++++++++++++
fs/xfs/xfs_reflink.h | 4 ++++
4 files changed, 36 insertions(+)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index b8d3c4f..127bf54 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -652,6 +652,8 @@ _xfs_dic2xflags(
if (di_flags2 & XFS_DIFLAG2_ANY) {
if (di_flags2 & XFS_DIFLAG2_DAX)
flags |= FS_XFLAG_DAX;
+ if (di_flags2 & XFS_DIFLAG2_REFLINK)
+ flags |= FS_XFLAG_REFLINK;
}

if (has_attr)
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 0e06a82..b8eceee 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1258,6 +1258,10 @@ xfs_ioctl_setattr(

trace_xfs_ioctl_setattr(ip);

+ code = xfs_reflink_check_flag_adjust(ip, &fa->fsx_xflags);
+ if (code)
+ return code;
+
code = xfs_ioctl_setattr_check_projid(ip, fa);
if (code)
return code;
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index b42ffb0..7c64104 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1782,3 +1782,29 @@ out_unlock:
trace_xfs_reflink_cow_eof_block_error(ip, error, _RET_IP_);
return error;
}
+
+/*
+ * Ensure that the only change we allow to the inode reflink flag is to clear
+ * it when the fs supports reflink and the size is zero.
+ */
+int
+xfs_reflink_check_flag_adjust(
+ struct xfs_inode *ip,
+ unsigned int *xflags)
+{
+ unsigned int chg;
+
+ chg = !!(*xflags & FS_XFLAG_REFLINK) ^ !!xfs_is_reflink_inode(ip);
+
+ if (!chg)
+ return 0;
+ if (!xfs_sb_version_hasreflink(&ip->i_mount->m_sb))
+ return -EOPNOTSUPP;
+ if (i_size_read(VFS_I(ip)) != 0)
+ return -EINVAL;
+ if (*xflags & FS_XFLAG_REFLINK) {
+ *xflags &= ~FS_XFLAG_REFLINK;
+ return 0;
+ }
+ return 0;
+}
diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index 437087c5..97e8705 100644
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -52,6 +52,10 @@ extern int xfs_reflink_unshare(struct xfs_inode *ip, xfs_off_t offset,
xfs_off_t len);
extern int xfs_reflink_cow_eof_block(struct xfs_inode *ip, xfs_off_t newsize);

+extern void xfs_reflink_get_lxflags(struct xfs_inode *ip, unsigned int *flags);
+extern int xfs_reflink_check_flag_adjust(struct xfs_inode *ip,
+ unsigned int *xflags);
+
/* xfs_aops.c */
extern int xfs_map_cow_blocks(struct inode *inode, xfs_off_t offset,
struct xfs_bmbt_irec *imap);