[11/25] vfs: create generic_remap_file_range_touch to update inode metadata

Commit Message

Darrick J. Wong Oct. 10, 2018, 12:13 a.m. UTC

From: Darrick J. Wong <[e-mail]>

Create a new VFS helper to handle inode metadata updates when remapping
into a file.  If the operation can possibly alter the file contents, we
must update the ctime and mtime and remove security privileges, just
like we do for regular file writes.  Wire up ocfs2 to ensure consistent
behavior.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 fs/ocfs2/refcounttree.c |    8 ++++++++
 fs/read_write.c         |   24 ++++++++++++++++++++++++
 fs/xfs/xfs_reflink.c    |   29 +++++++----------------------
 include/linux/fs.h      |    1 +
 4 files changed, 40 insertions(+), 22 deletions(-)

Patch

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 36c56dfbe485..ee1ed11379b3 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4855,6 +4855,14 @@  int ocfs2_reflink_remap_range(struct file *file_in,
 	if (ret <= 0)
 		goto out_unlock;
 
+	/*
+	 * Update inode timestamps and remove security privileges before we
+	 * take the ilock.
+	 */
+	ret = generic_remap_file_range_touch(file_out, is_dedupe);
+	if (ret)
+		goto out_unlock;
+
 	/* Lock out changes to the allocation maps and remap. */
 	down_write(&OCFS2_I(inode_in)->ip_alloc_sem);
 	if (!same_inode)
diff --git a/fs/read_write.c b/fs/read_write.c
index b4acfb45d916..020bb7fdf431 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1790,6 +1790,30 @@  int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 }
 EXPORT_SYMBOL(generic_remap_file_range_prep);
 
+/* Update inode timestamps and remove security privileges when remapping. */
+int generic_remap_file_range_touch(struct file *file, bool is_dedupe)
+{
+	int ret;
+
+	/* If can't alter the file contents, we're done. */
+	if (is_dedupe)
+		return 0;
+
+	/* Update the timestamps, since we can alter file contents. */
+	if (!(file->f_mode & FMODE_NOCMTIME)) {
+		ret = file_update_time(file);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * Clear the security bits if the process is not being run by root.
+	 * This keeps people from modifying setuid and setgid binaries.
+	 */
+	return file_remove_privs(file);
+}
+EXPORT_SYMBOL(generic_remap_file_range_touch);
+
 int do_clone_file_range(struct file *file_in, loff_t pos_in,
 			struct file *file_out, loff_t pos_out, u64 len)
 {
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 4cf1e52efbff..0d67b2d0b3d4 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1330,28 +1330,13 @@  xfs_reflink_remap_prep(
 	truncate_inode_pages_range(&inode_out->i_data, pos_out,
 				   PAGE_ALIGN(pos_out + *len) - 1);
 
-	/* If we're altering the file contents... */
-	if (!is_dedupe) {
-		/*
-		 * ...update the timestamps (which will grab the ilock again
-		 * from xfs_fs_dirty_inode, so we have to call it before we
-		 * take the ilock).
-		 */
-		if (!(file_out->f_mode & FMODE_NOCMTIME)) {
-			ret = file_update_time(file_out);
-			if (ret)
-				goto out_unlock;
-		}
-
-		/*
-		 * ...clear the security bits if the process is not being run
-		 * by root.  This keeps people from modifying setuid and setgid
-		 * binaries.
-		 */
-		ret = file_remove_privs(file_out);
-		if (ret)
-			goto out_unlock;
-	}
+	/*
+	 * Update inode timestamps and remove security privileges before we
+	 * take the ilock.
+	 */
+	ret = generic_remap_file_range_touch(file_out, is_dedupe);
+	if (ret)
+		goto out_unlock;
 
 	return 1;
 out_unlock:
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d8f90bdd34e2..661b9ef32d2b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1833,6 +1833,7 @@  extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
 extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 					 struct file *file_out, loff_t pos_out,
 					 u64 *count, bool is_dedupe);
+extern int generic_remap_file_range_touch(struct file *file, bool is_dedupe);
 extern int do_clone_file_range(struct file *file_in, loff_t pos_in,
 			       struct file *file_out, loff_t pos_out, u64 len);
 extern int vfs_clone_file_range(struct file *file_in, loff_t pos_in,