The patch titled
r/o bind mounts: make access() use new r/o helper
has been removed from the -mm tree. Its filename was
r-o-bind-mounts-make-access-use-new-r-o-helper.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: r/o bind mounts: make access() use new r/o helper
From: Dave Hansen <haveblue@xxxxxxxxxx>
It is OK to let access() go without using a mnt_want/drop_write() pair because
it doesn't actually do writes to the filesystem, and it is inherently racy
anyway. This is a rare case when it is OK to use __mnt_is_readonly()
directly.
Acked-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <haveblue@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/open.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff -puN fs/open.c~r-o-bind-mounts-make-access-use-new-r-o-helper fs/open.c
--- a/fs/open.c~r-o-bind-mounts-make-access-use-new-r-o-helper
+++ a/fs/open.c
@@ -459,8 +459,17 @@ asmlinkage long sys_faccessat(int dfd, c
if(res || !(mode & S_IWOTH) ||
special_file(nd.path.dentry->d_inode->i_mode))
goto out_path_release;
-
- if(IS_RDONLY(nd.path.dentry->d_inode))
+ /*
+ * This is a rare case where using __mnt_is_readonly()
+ * is OK without a mnt_want/drop_write() pair. Since
+ * no actual write to the fs is performed here, we do
+ * not need to telegraph to that to anyone.
+ *
+ * By doing this, we accept that this access is
+ * inherently racy and know that the fs may change
+ * state before we even see this result.
+ */
+ if (__mnt_is_readonly(nd.path.mnt))
res = -EROFS;
out_path_release:
_
Patches currently in -mm which might be from haveblue@xxxxxxxxxx are
git-vfs.patch
hugetlb-decrease-hugetlb_lock-cycling-in-gather_surplus_huge_pages.patch
mm-make-mem_map-allocation-continuous.patch
vfs-create-proc-pid-mountinfo.patch
vfs-mountinfo-mm-fix.patch
vfs-pnode-cleanup.patch
vfs-mountinfo-stable-peer-group-id.patch
vfs-mountinfo-show-dominating-group-id.patch
vfs-optimization-to-proc-pid-mountinfo-patch.patch
vfs-mountinfo-only-show-mounts-under-tasks-root.patch
kprobes-prevent-probing-of-preempt_schedule.patch
kprobes-prevent-probing-of-preempt_schedule-fix.patch
kprobes-prevent-probing-of-preempt_schedule-checkpatch-fixes.patch
reiser4.patch
page-owner-tracking-leak-detector.patch
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