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| author | Dave Hansen <haveblue@us.ibm.com> | 2008-02-15 14:38:01 -0800 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2008-04-19 00:29:28 -0400 |
| commit | ad775f5a8faa5845377f093ca11caf577404add9 (patch) | |
| tree | f124ff1038672b8d2ef004d75c844f740d8fe52b /fs | |
| parent | 2e4b7fcd926006531935a4c79a5e9349fe51125b (diff) | |
| download | linux-stable-ad775f5a8faa5845377f093ca11caf577404add9.tar.gz linux-stable-ad775f5a8faa5845377f093ca11caf577404add9.tar.bz2 linux-stable-ad775f5a8faa5845377f093ca11caf577404add9.zip | |
[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')
| -rw-r--r-- | fs/file_table.c | 11 | ||||
| -rw-r--r-- | fs/open.c | 12 | ||||
| -rw-r--r-- | fs/super.c | 3 |
3 files changed, 23 insertions, 3 deletions
diff --git a/fs/file_table.c b/fs/file_table.c index 71efc7000226..7a0a9b872251 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -42,6 +42,7 @@ static inline void file_free_rcu(struct rcu_head *head) static inline void file_free(struct file *f) { percpu_counter_dec(&nr_files); + file_check_state(f); call_rcu(&f->f_u.fu_rcuhead, file_free_rcu); } @@ -207,6 +208,7 @@ int init_file(struct file *file, struct vfsmount *mnt, struct dentry *dentry, * that we can do debugging checks at __fput() */ if ((mode & FMODE_WRITE) && !special_file(dentry->d_inode->i_mode)) { + file_take_write(file); error = mnt_want_write(mnt); WARN_ON(error); } @@ -237,8 +239,13 @@ void drop_file_write_access(struct file *file) struct inode *inode = dentry->d_inode; put_write_access(inode); - if (!special_file(inode->i_mode)) - mnt_drop_write(mnt); + + if (special_file(inode->i_mode)) + return; + if (file_check_writeable(file) != 0) + return; + mnt_drop_write(mnt); + file_release_write(file); } EXPORT_SYMBOL_GPL(drop_file_write_access); diff --git a/fs/open.c b/fs/open.c index e58382d57e72..b70e7666bb2c 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; diff --git a/fs/super.c b/fs/super.c index 01d5c40e9119..1f8f05ede437 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(); /* |