From 49e0d02cf018d4edf24bfc8531a816a26367e4ce Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 15 Feb 2008 14:37:32 -0800 Subject: [PATCH] r/o bind mounts: drop write during emergency remount The emergency remount code forcibly removes FMODE_WRITE from filps. The r/o bind mount code notices that this was done without a proper mnt_drop_write() and properly gives a warning. This patch does a mnt_drop_write() to keep everything balanced. Acked-by: Al Viro Signed-off-by: Christoph Hellwig Signed-off-by: Dave Hansen Signed-off-by: Al Viro --- fs/super.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'fs/super.c') diff --git a/fs/super.c b/fs/super.c index 09008dbd264..01d5c40e911 100644 --- a/fs/super.c +++ b/fs/super.c @@ -37,6 +37,7 @@ #include #include #include +#include #include @@ -567,10 +568,26 @@ static void mark_files_ro(struct super_block *sb) { struct file *f; +retry: file_list_lock(); list_for_each_entry(f, &sb->s_files, f_u.fu_list) { - if (S_ISREG(f->f_path.dentry->d_inode->i_mode) && file_count(f)) - f->f_mode &= ~FMODE_WRITE; + struct vfsmount *mnt; + if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) + continue; + if (!file_count(f)) + continue; + if (!(f->f_mode & FMODE_WRITE)) + continue; + f->f_mode &= ~FMODE_WRITE; + mnt = mntget(f->f_path.mnt); + file_list_unlock(); + /* + * This can sleep, so we can't hold + * the file_list_lock() spinlock. + */ + mnt_drop_write(mnt); + mntput(mnt); + goto retry; } file_list_unlock(); } -- cgit v1.2.3 From ad775f5a8faa5845377f093ca11caf577404add9 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 15 Feb 2008 14:38:01 -0800 Subject: [PATCH] r/o bind mounts: debugging for missed calls There have been a few oopses caused by 'struct file's with NULL f_vfsmnts. There was also a set of potentially missed mnt_want_write()s from dentry_open() calls. This patch provides a very simple debugging framework to catch these kinds of bugs. It will WARN_ON() them, but should stop us from having any oopses or mnt_writer count imbalances. I'm quite convinced that this is a good thing because it found bugs in the stuff I was working on as soon as I wrote it. [hch: made it conditional on a debug option. But it's still a little bit too ugly] [hch: merged forced remount r/o fix from Dave and akpm's fix for the fix] Signed-off-by: Dave Hansen Acked-by: Al Viro Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/super.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'fs/super.c') diff --git a/fs/super.c b/fs/super.c index 01d5c40e911..1f8f05ede43 100644 --- a/fs/super.c +++ b/fs/super.c @@ -579,6 +579,9 @@ retry: if (!(f->f_mode & FMODE_WRITE)) continue; f->f_mode &= ~FMODE_WRITE; + if (file_check_writeable(f) != 0) + continue; + file_release_write(f); mnt = mntget(f->f_path.mnt); file_list_unlock(); /* -- cgit v1.2.3