xfs: add a ->xchg_file_range handler

Add a function to handle file range exchange requests from the vfs.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 3a66a1a4623a..236368087158 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -24,6 +24,7 @@
 #include "xfs_pnfs.h"
 #include "xfs_iomap.h"
 #include "xfs_reflink.h"
+#include "xfs_xchgrange.h"
 
 #include <linux/dax.h>
 #include <linux/falloc.h>
@@ -1151,6 +1152,74 @@ out_unlock:
 }
 
 STATIC int
+xfs_file_xchg_range(
+	struct file		*file1,
+	struct file		*file2,
+	struct file_xchg_range	*fxr)
+{
+	struct inode		*inode1 = file_inode(file1);
+	struct inode		*inode2 = file_inode(file2);
+	struct xfs_inode	*ip1 = XFS_I(inode1);
+	struct xfs_inode	*ip2 = XFS_I(inode2);
+	struct xfs_mount	*mp = ip1->i_mount;
+	unsigned int		priv_flags = 0;
+	bool			use_logging = false;
+	int			error;
+
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	/* Update cmtime if the fd/inode don't forbid it. */
+	if (likely(!(file1->f_mode & FMODE_NOCMTIME) && !IS_NOCMTIME(inode1)))
+		priv_flags |= XFS_XCHG_RANGE_UPD_CMTIME1;
+	if (likely(!(file2->f_mode & FMODE_NOCMTIME) && !IS_NOCMTIME(inode2)))
+		priv_flags |= XFS_XCHG_RANGE_UPD_CMTIME2;
+
+	/* Lock both files against IO */
+	error = xfs_ilock2_io_mmap(ip1, ip2);
+	if (error)
+		goto out_err;
+
+	/* Prepare and then exchange file contents. */
+	error = xfs_xchg_range_prep(file1, file2, fxr);
+	if (error)
+		goto out_unlock;
+
+	/* Get permission to use log-assisted file content swaps. */
+	error = xfs_xchg_range_grab_log_assist(mp,
+			!(fxr->flags & FILE_XCHG_RANGE_NONATOMIC),
+			&use_logging);
+	if (error)
+		goto out_unlock;
+	if (use_logging)
+		priv_flags |= XFS_XCHG_RANGE_LOGGED;
+
+	error = xfs_xchg_range(ip1, ip2, fxr, priv_flags);
+	if (error)
+		goto out_drop_feat;
+
+	/*
+	 * Finish the exchange by removing special file privileges like any
+	 * other file write would do.  This may involve turning on support for
+	 * logged xattrs if either file has security capabilities, which means
+	 * xfs_xchg_range_grab_log_assist before xfs_attr_grab_log_assist.
+	 */
+	error = generic_xchg_file_range_finish(file1, file2);
+	if (error)
+		goto out_drop_feat;
+
+out_drop_feat:
+	if (use_logging)
+		xfs_xchg_range_rele_log_assist(mp);
+out_unlock:
+	xfs_iunlock2_io_mmap(ip1, ip2);
+out_err:
+	if (error)
+		trace_xfs_file_xchg_range_error(ip2, error, _RET_IP_);
+	return error;
+}
+
+STATIC int
 xfs_file_open(
 	struct inode	*inode,
 	struct file	*file)
@@ -1438,6 +1507,7 @@ const struct file_operations xfs_file_operations = {
 	.fallocate	= xfs_file_fallocate,
 	.fadvise	= xfs_file_fadvise,
 	.remap_file_range = xfs_file_remap_range,
+	.xchg_file_range = xfs_file_xchg_range,
 };
 
 const struct file_operations xfs_dir_file_operations = {