fat: Fix ATTR_RO in the case of (~umask & S_WUGO) == 0
If inode->i_mode doesn't have S_WUGO, current code assumes it means
ATTR_RO. However, if (~[ufd]mask & S_WUGO) == 0, inode->i_mode can't
hold S_WUGO. Therefore the updated directory entry will always have
ATTR_RO.
This adds fat_mode_can_hold_ro() to check it. And if inode->i_mode
can't hold, uses -i_attrs to hold ATTR_RO instead.
With this, we don't set ATTR_RO unless users change it via ioctl() if
(~[ufd]mask & S_WUGO) == 0.
And on FAT_IOCTL_GET_ATTRIBUTES path, this adds ->i_mutex to it for
not returning the partially updated attributes by FAT_IOCTL_SET_ATTRIBUTES
to userland.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/fat/file.c b/fs/fat/file.c
index f5a7e90..81b15c6 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -27,7 +27,12 @@
switch (cmd) {
case FAT_IOCTL_GET_ATTRIBUTES:
{
- u32 attr = fat_make_attrs(inode);
+ u32 attr;
+
+ mutex_lock(&inode->i_mutex);
+ attr = fat_make_attrs(inode);
+ mutex_unlock(&inode->i_mutex);
+
return put_user(attr, user_attr);
}
case FAT_IOCTL_SET_ATTRIBUTES: