[PATCH 12/28] vfs: remap helper should update destination inode metadata

Darrick J. Wong
2018-10-22T00:31:23Z

Extend generic_remap_file_range_prep 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.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
---
fs/read_write.c | 19 +++++++++++++++++++
fs/xfs/xfs_reflink.c | 23 -----------------------
2 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index ebcbfc4f2907..b61bd3fc7154 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1820,6 +1820,25 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
if (ret)
return ret;

+ /* If can't alter the file contents, we're done. */
+ if (!(remap_flags & REMAP_FILE_DEDUP)) {
+ /* Update the timestamps, since we can alter file contents. */
+ if (!(file_out->f_mode & FMODE_NOCMTIME)) {
+ ret = file_update_time(file_out);
+ 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.
+ */
+ ret = file_remove_privs(file_out);
+ if (ret)
+ return ret;
+ }
+
return 1;
}
EXPORT_SYMBOL(generic_remap_file_range_prep);
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 29aab196ce7e..2d7dd8b28d7c 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1372,29 +1372,6 @@ 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 (!(remap_flags & REMAP_FILE_DEDUP)) {
- /*
- * ...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;
- }
-
return 1;
out_unlock:
xfs_reflink_remap_unlock(file_in, file_out);