The patch titled
vfs-protect-remounting-superblock-read-only-update.txt
has been added to the -mm tree. Its filename is
vfs-protect-remounting-superblock-read-only-update.patch
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------------------------------------------------------
Subject: vfs-protect-remounting-superblock-read-only-update.txt
From: Miklos Szeredi <mszeredi@xxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/namespace.c | 41 ++++++++++++++++++++--------------------
include/linux/mount.h | 1
2 files changed, 22 insertions(+), 20 deletions(-)
diff -puN fs/namespace.c~vfs-protect-remounting-superblock-read-only-update fs/namespace.c
--- a/fs/namespace.c~vfs-protect-remounting-superblock-read-only-update
+++ a/fs/namespace.c
@@ -438,11 +438,17 @@ int sb_prepare_remount_readonly(struct s
}
}
}
+ list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
+ if (mnt->mnt_flags & MNT_WRITE_HOLD) {
+ if (!err) {
+ mnt->mnt_flags |= MNT_READONLY | MNT_WAS_WRITE;
+ smp_wmb();
+ }
+ mnt->mnt_flags &= ~MNT_WRITE_HOLD;
+ }
+ }
br_write_unlock(vfsmount_lock);
- if (err)
- sb_cancel_remount_readonly(sb);
-
return err;
}
@@ -452,12 +458,11 @@ void sb_cancel_remount_readonly(struct s
br_write_lock(vfsmount_lock);
list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
- if (mnt->mnt_flags & MNT_WRITE_HOLD)
- mnt->mnt_flags &= ~MNT_WRITE_HOLD;
+ if (mnt->mnt_flags & MNT_WAS_WRITE)
+ mnt->mnt_flags &= ~(MNT_WAS_WRITE | MNT_READONLY);
}
br_write_unlock(vfsmount_lock);
- wake_up_all(&sb->s_wait_remount_readonly);
}
void sb_finish_remount_readonly(struct super_block *sb)
@@ -466,15 +471,11 @@ void sb_finish_remount_readonly(struct s
br_write_lock(vfsmount_lock);
list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
- if (!(mnt->mnt_flags & MNT_READONLY)) {
- mnt->mnt_flags |= MNT_READONLY;
- smp_wmb();
- mnt->mnt_flags &= ~MNT_WRITE_HOLD;
- }
+ if (mnt->mnt_flags & MNT_WAS_WRITE)
+ mnt->mnt_flags &= ~MNT_WAS_WRITE;
}
sb->s_flags |= MS_RDONLY;
br_write_unlock(vfsmount_lock);
- wake_up_all(&sb->s_wait_remount_readonly);
}
void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
@@ -1844,6 +1845,14 @@ int do_add_mount(struct vfsmount *newmnt
mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL);
+ /* Locking is necessary to prevent racing with remount r/o */
+ down_read(&newmnt->mnt_sb->s_umount);
+ if (newmnt->mnt_sb->s_flags & MS_RDONLY)
+ mnt_flags |= MNT_READONLY;
+
+ newmnt->mnt_flags = mnt_flags;
+ up_read(&newmnt->mnt_sb->s_umount);
+
down_write(&namespace_sem);
/* Something was mounted here while we slept */
while (d_mountpoint(path->dentry) &&
@@ -1863,14 +1872,6 @@ int do_add_mount(struct vfsmount *newmnt
if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
goto unlock;
- /* Locking is necessary to prevent racing with remount r/o */
- br_read_lock(vfsmount_lock);
- if (newmnt->mnt_sb->s_flags & MS_RDONLY)
- mnt_flags |= MNT_READONLY;
-
- newmnt->mnt_flags = mnt_flags;
- br_read_unlock(vfsmount_lock);
-
if ((err = graft_tree(newmnt, path)))
goto unlock;
diff -puN include/linux/mount.h~vfs-protect-remounting-superblock-read-only-update include/linux/mount.h
--- a/include/linux/mount.h~vfs-protect-remounting-superblock-read-only-update
+++ a/include/linux/mount.h
@@ -30,6 +30,7 @@ struct mnt_namespace;
#define MNT_SHRINKABLE 0x100
#define MNT_WRITE_HOLD 0x200
+#define MNT_WAS_WRITE 0x400 /* used by remount to remember write mounts */
#define MNT_SHARED 0x1000 /* if the vfsmount is a shared mount */
#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
_
Patches currently in -mm which might be from mszeredi@xxxxxxx are
origin.patch
vfs-fix-infinite-loop-caused-by-clone_mnt-race.patch
vfs-ignore-error-on-forced-remount.patch
vfs-fix-per-mount-read-write.patch
vfs-add-sb_force_remount_readonly-helper.patch
vfs-allow-mnt_want_write-to-sleep.patch
vfs-keep-list-of-mounts-for-each-superblock.patch
vfs-protect-remounting-superblock-read-only.patch
vfs-protect-remounting-superblock-read-only-update.patch
vfs-fs_may_remount_ro-turn-unnecessary-check-into-a-warn_on.patch
vfs-mark-mounts-read-only-on-forced-remount.patch
fuse-use-clear_highpage-and-km_user0-instead-of-km_user1.patch
fuse-use-release_pages.patch
--
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