diff options
| -rw-r--r-- | fs/namespace.c | 50 | ||||
| -rw-r--r-- | include/linux/mount.h | 1 |
2 files changed, 44 insertions, 7 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index e3ce18d..678f7ce 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -105,7 +105,11 @@ struct vfsmount *alloc_vfsmnt(const char *name) */ int __mnt_is_readonly(struct vfsmount *mnt) { - return (mnt->mnt_sb->s_flags & MS_RDONLY); + if (mnt->mnt_flags & MNT_READONLY) + return 1; + if (mnt->mnt_sb->s_flags & MS_RDONLY) + return 1; + return 0; } EXPORT_SYMBOL_GPL(__mnt_is_readonly); @@ -305,7 +309,7 @@ void mnt_drop_write(struct vfsmount *mnt) } EXPORT_SYMBOL_GPL(mnt_drop_write); -int mnt_make_readonly(struct vfsmount *mnt) +static int mnt_make_readonly(struct vfsmount *mnt) { int ret = 0; @@ -318,15 +322,25 @@ int mnt_make_readonly(struct vfsmount *mnt) goto out; } /* - * actually set mount's r/o flag here to make - * __mnt_is_readonly() true, which keeps anyone - * from doing a successful mnt_want_write(). + * nobody can do a successful mnt_want_write() with all + * of the counts in MNT_DENIED_WRITE and the locks held. */ + spin_lock(&vfsmount_lock); + if (!ret) + mnt->mnt_flags |= MNT_READONLY; + spin_unlock(&vfsmount_lock); out: unlock_mnt_writers(); return ret; } +static void __mnt_unmake_readonly(struct vfsmount *mnt) +{ + spin_lock(&vfsmount_lock); + mnt->mnt_flags &= ~MNT_READONLY; + spin_unlock(&vfsmount_lock); +} + int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) { mnt->mnt_sb = sb; @@ -693,7 +707,7 @@ static int show_vfsmnt(struct seq_file *m, void *v) seq_putc(m, '.'); mangle(m, mnt->mnt_sb->s_subtype); } - seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); + seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { if (mnt->mnt_sb->s_flags & fs_infop->flag) seq_puts(m, fs_infop->str); @@ -1295,6 +1309,23 @@ out: return err; } +static int change_mount_flags(struct vfsmount *mnt, int ms_flags) +{ + int error = 0; + int readonly_request = 0; + + if (ms_flags & MS_RDONLY) + readonly_request = 1; + if (readonly_request == __mnt_is_readonly(mnt)) + return 0; + + if (readonly_request) + error = mnt_make_readonly(mnt); + else + __mnt_unmake_readonly(mnt); + return error; +} + /* * change filesystem flags. dir should be a physical root of filesystem. * If you've mounted a non-root directory somewhere and want to do remount @@ -1317,7 +1348,10 @@ static noinline int do_remount(struct nameidata *nd, int flags, int mnt_flags, return -EINVAL; down_write(&sb->s_umount); - err = do_remount_sb(sb, flags, data, 0); + if (flags & MS_BIND) + err = change_mount_flags(nd->path.mnt, flags); + else + err = do_remount_sb(sb, flags, data, 0); if (!err) nd->path.mnt->mnt_flags = mnt_flags; up_write(&sb->s_umount); @@ -1701,6 +1735,8 @@ long do_mount(char *dev_name, char *dir_name, char *type_page, mnt_flags |= MNT_NODIRATIME; if (flags & MS_RELATIME) mnt_flags |= MNT_RELATIME; + if (flags & MS_RDONLY) + mnt_flags |= MNT_READONLY; flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT); diff --git a/include/linux/mount.h b/include/linux/mount.h index 8c8e943..d6600e3 100644 --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -29,6 +29,7 @@ struct mnt_namespace; #define MNT_NOATIME 0x08 #define MNT_NODIRATIME 0x10 #define MNT_RELATIME 0x20 +#define MNT_READONLY 0x40 /* does the user want this to be r/o? */ #define MNT_SHRINKABLE 0x100 #define MNT_IMBALANCED_WRITE_COUNT 0x200 /* just for debugging */ |
