[PATCH] r/o bind mounts: elevate count for xfs timestamp updates

Elevate the write count during the xfs m/ctime updates.

XFS has to do it's own timestamp updates due to an unfortunate VFS
design limitation, so it will have to track writers by itself aswell.

[hch: split out from the touch_atime patch as it's not related to it at all]

Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c
index 21c0dbc74093..1ebd8004469c 100644
--- a/fs/xfs/linux-2.6/xfs_lrw.c
+++ b/fs/xfs/linux-2.6/xfs_lrw.c
@@ -51,6 +51,7 @@
 #include "xfs_vnodeops.h"
 
 #include <linux/capability.h>
+#include <linux/mount.h>
 #include <linux/writeback.h>
 
 
@@ -670,10 +671,16 @@ start:
         if (new_size > xip->i_size)
                 xip->i_new_size = new_size;
 
-        if (likely(!(ioflags & IO_INVIS))) {
+        /*
+         * We're not supposed to change timestamps in readonly-mounted
+         * filesystems.  Throw it away if anyone asks us.
+         */
+        if (likely(!(ioflags & IO_INVIS) &&
+                   !mnt_want_write(file->f_path.mnt))) {
                 file_update_time(file);
                 xfs_ichgtime_fast(xip, inode,
                                   XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+                mnt_drop_write(file->f_path.mnt);
         }
 
         /*