[PATCH] r/o bind mounts: elevate write count for ioctls()
Some ioctl()s can cause writes to the filesystem. Take these, and make them
use mnt_want/drop_write() instead.
[AV: updated]
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/fat/file.c b/fs/fat/file.c
index c614175..2a3bed9 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -8,6 +8,7 @@
#include <linux/capability.h>
#include <linux/module.h>
+#include <linux/mount.h>
#include <linux/time.h>
#include <linux/msdos_fs.h>
#include <linux/smp_lock.h>
@@ -46,10 +47,9 @@
mutex_lock(&inode->i_mutex);
- if (IS_RDONLY(inode)) {
- err = -EROFS;
- goto up;
- }
+ err = mnt_want_write(filp->f_path.mnt);
+ if (err)
+ goto up_no_drop_write;
/*
* ATTR_VOLUME and ATTR_DIR cannot be changed; this also
@@ -105,7 +105,9 @@
MSDOS_I(inode)->i_attrs = attr & ATTR_UNUSED;
mark_inode_dirty(inode);
- up:
+up:
+ mnt_drop_write(filp->f_path.mnt);
+up_no_drop_write:
mutex_unlock(&inode->i_mutex);
return err;
}