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authorDave Hansen <haveblue@us.ibm.com>2008-02-15 14:38:01 -0800
committerAl Viro <viro@zeniv.linux.org.uk>2008-04-19 00:29:28 -0400
commitad775f5a8faa5845377f093ca11caf577404add9 (patch)
treef124ff1038672b8d2ef004d75c844f740d8fe52b /fs/open.c
parent2e4b7fcd926006531935a4c79a5e9349fe51125b (diff)
downloadop-kernel-dev-ad775f5a8faa5845377f093ca11caf577404add9.zip
op-kernel-dev-ad775f5a8faa5845377f093ca11caf577404add9.tar.gz
[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 <haveblue@us.ibm.com> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/open.c')
-rw-r--r--fs/open.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/fs/open.c b/fs/open.c
index e58382d..b70e766 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -806,6 +806,8 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
error = __get_file_write_access(inode, mnt);
if (error)
goto cleanup_file;
+ if (!special_file(inode->i_mode))
+ file_take_write(f);
}
f->f_mapping = inode->i_mapping;
@@ -847,8 +849,16 @@ cleanup_all:
fops_put(f->f_op);
if (f->f_mode & FMODE_WRITE) {
put_write_access(inode);
- if (!special_file(inode->i_mode))
+ if (!special_file(inode->i_mode)) {
+ /*
+ * We don't consider this a real
+ * mnt_want/drop_write() pair
+ * because it all happenend right
+ * here, so just reset the state.
+ */
+ file_reset_write(f);
mnt_drop_write(mnt);
+ }
}
file_kill(f);
f->f_path.dentry = NULL;
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