The patch titled
create file_drop_write_access() helper
has been added to the -mm tree. Its filename is
create-file_drop_write_access-helper.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: create file_drop_write_access() helper
From: Dave Hansen <haveblue@xxxxxxxxxx>
These should fix the bug that Erez Zadok <ezk@xxxxxxxxxxxxx>
reported:
Stopping RPC idmapd:
kernel: __fput() of writeable file with no mnt_want_write()
kernel: WARNING: at fs/file_table.c:262 __fput()
kernel: [<c010283e>] show_trace_log_lvl+0x12/0x25
kernel: [<c0103042>] show_trace+0xd/0x10
...
The actual bug was a missed mnt_want_write() when a
filp was allocated with get_empty_filp() and then
made writable. Using alloc_file(), instead, fixes
that.
--
If someone decides to demote a file from r/w to just
r/o, they can use this same code as __fput().
NFS does just that, and will use this in the next
patch.
Signed-off-by: Dave Hansen <haveblue@xxxxxxxxxx>
Cc: Erez Zadok <ezk@xxxxxxxxxxxxx>
Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxx>
Cc: "J Bruce Fields" <bfields@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/file_table.c | 46 +++++++++++++++++++++++++++--------------
include/linux/file.h | 1
2 files changed, 32 insertions(+), 15 deletions(-)
diff -puN fs/file_table.c~create-file_drop_write_access-helper fs/file_table.c
--- a/fs/file_table.c~create-file_drop_write_access-helper
+++ a/fs/file_table.c
@@ -223,6 +223,34 @@ void fastcall fput(struct file *file)
EXPORT_SYMBOL(fput);
+/**
+ * drop_file_write_access - give up ability to write to a file
+ * @file: the file to which we will stop writing
+ *
+ * This is a central place which will give up the ability
+ * to write to @file, along with access to write through
+ * its vfsmount.
+ */
+void drop_file_write_access(struct file *file)
+{
+ struct dentry *dentry = file->f_path.dentry;
+ struct vfsmount *mnt = file->f_path.mnt;
+ struct inode *inode = dentry->d_inode;
+
+ put_write_access(inode);
+ if (!special_file(inode->i_mode)) {
+ if (file->f_mnt_write_state == FILE_MNT_WRITE_TAKEN) {
+ mnt_drop_write(mnt);
+ file->f_mnt_write_state |= FILE_MNT_WRITE_RELEASED;
+ } else {
+ printk(KERN_WARNING "dropping write access on "
+ "file with no mnt_want_write()\n");
+ WARN_ON(1);
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(drop_file_write_access);
+
/* __fput is called from task context when aio completion releases the last
* last use of a struct file *. Do not use otherwise.
*/
@@ -248,21 +276,9 @@ void fastcall __fput(struct file *file)
if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL))
cdev_put(inode->i_cdev);
fops_put(file->f_op);
- if (file->f_mode & FMODE_WRITE) {
- put_write_access(inode);
- if (!special_file(inode->i_mode)) {
- if (file->f_mnt_write_state == FILE_MNT_WRITE_TAKEN) {
- mnt_drop_write(mnt);
- file->f_mnt_write_state |=
- FILE_MNT_WRITE_RELEASED;
- } else {
- printk(KERN_WARNING "__fput() of writeable "
- "file with no "
- "mnt_want_write()\n");
- WARN_ON(1);
- }
- }
- }
+ if (file->f_mode & FMODE_WRITE)
+ drop_file_write_access(file);
+
put_pid(file->f_owner.pid);
file_kill(file);
file->f_path.dentry = NULL;
diff -puN include/linux/file.h~create-file_drop_write_access-helper include/linux/file.h
--- a/include/linux/file.h~create-file_drop_write_access-helper
+++ a/include/linux/file.h
@@ -61,6 +61,7 @@ extern struct kmem_cache *filp_cachep;
extern void FASTCALL(__fput(struct file *));
extern void FASTCALL(fput(struct file *));
+extern void drop_file_write_access(struct file *file);
struct file_operations;
struct vfsmount;
_
Patches currently in -mm which might be from haveblue@xxxxxxxxxx are
markers-fix-warnings.patch
maps4-add-proportional-set-size-accounting-in-smaps.patch
maps4-rework-task_size-macros.patch
maps4-move-is_swap_pte.patch
maps4-introduce-a-generic-page-walker.patch
maps4-use-pagewalker-in-clear_refs-and-smaps.patch
maps4-simplify-interdependence-of-maps-and-smaps.patch
maps4-move-clear_refs-code-to-task_mmuc.patch
maps4-regroup-task_mmu-by-interface.patch
maps4-add-proc-pid-pagemap-interface.patch
maps4-add-proc-kpagecount-interface.patch
maps4-add-proc-kpageflags-interface.patch
maps4-make-page-monitoring-proc-file-optional.patch
maps4-make-page-monitoring-proc-file-optional-fix.patch
hugetlb-split-alloc_huge_page-into-private-and-shared-components.patch
hugetlb-split-alloc_huge_page-into-private-and-shared-components-checkpatch-fixes.patch
hugetlb-fix-quota-management-for-private-mappings.patch
hugetlb-debit-quota-in-alloc_huge_page.patch
hugetlb-allow-bulk-updating-in-hugetlb__quota.patch
hugetlb-enforce-quotas-during-reservation-for-shared-mappings.patch
add-remove_memory-for-ppc64-2.patch
enable-hotplug-memory-remove-for-ppc64.patch
add-arch-specific-walk_memory_remove-for-ppc64.patch
do-namei_flags-calculation-inside-open_namei.patch
make-open_namei-return-a-filp.patch
kill-do_filp_open.patch
kill-filp_open.patch
kill-filp_open-checkpatch-fixes.patch
rename-open_namei-to-open_pathname.patch
rename-open_namei-to-open_pathname-fix.patch
r-o-bind-mounts-stub-functions.patch
r-o-bind-mounts-do_rmdir-elevate-write-count.patch
r-o-bind-mounts-elevate-mnt-writers-for-callers-of-vfs_mkdir.patch
r-o-bind-mounts-elevate-mnt-writers-for-vfs_unlink-callers.patch
r-o-bind-mounts-elevate-mount-count-for-extended-attributes.patch
r-o-bind-mounts-elevate-write-count-during-entire-ncp_ioctl.patch
r-o-bind-mounts-elevate-write-count-during-entire-ncp_ioctl-fix.patch
r-o-bind-mounts-elevate-write-count-for-do_sys_utime-and-touch_atime.patch
r-o-bind-mounts-elevate-write-count-for-do_utimes.patch
r-o-bind-mounts-elevate-write-count-for-file_update_time.patch
r-o-bind-mounts-elevate-write-count-for-link-and-symlink-calls.patch
r-o-bind-mounts-elevate-write-count-for-some-ioctls.patch
r-o-bind-mounts-elevate-write-count-for-some-ioctls-checkpatch-fixes.patch
r-o-bind-mounts-elevate-write-count-for-some-ioctls-vs-forbid-user-to-change-file-flags-on-quota-files.patch
r-o-bind-mounts-elevate-write-count-opened-files.patch
r-o-bind-mounts-elevate-write-count-over-calls-to-vfs_rename.patch
r-o-bind-mounts-elevate-writer-count-for-chown-and-friends.patch
r-o-bind-mounts-elevate-writer-count-for-do_sys_truncate.patch
r-o-bind-mounts-make-access-use-mnt-check.patch
r-o-bind-mounts-nfs-check-mnt-instead-of-superblock-directly.patch
r-o-bind-mounts-nfs-check-mnt-instead-of-superblock-directly-checkpatch-fixes.patch
r-o-bind-mounts-sys_mknodat-elevate-write-count-for-vfs_mknod-create.patch
r-o-bind-mounts-track-number-of-mount-writers.patch
r-o-bind-mounts-track-number-of-mount-writers-make-lockdep-happy-with-r-o-bind-mounts.patch
r-o-bind-mounts-track-number-of-mount-writer-fix-buggy-loop.patch
r-o-bind-mounts-track-number-of-mount-writer-fix-buggy-loop-checkpatch-fixes.patch
r-o-bind-mounts-honor-r-w-changes-at-do_remount-time.patch
keep-track-of-mnt_writer-state-of-struct-file.patch
create-file_drop_write_access-helper.patch
fix-up-new-filp-allocators.patch
reiser4.patch
page-owner-tracking-leak-detector.patch
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