Re: UBIFS assert failed in ubifs_dirty_inode

From: Jeff Angielski
Date: Tue Jan 26 2010 - 22:07:36 EST

Matt Mackall wrote:
On Tue, 2010-01-26 at 20:44 -0500, Jeff Angielski wrote:
Artem Bityutskiy wrote:
On Mon, 2010-01-25 at 23:48 -0600, Matt Mackall wrote:
Hmm. I'd just as soon drop it entirely. Here's a patch. Herbert, you
want to send this through your crypto tree?

random: drop weird m_time/a_time manipulation

No other driver does anything remotely like this that I know of except
for the tty drivers, and I can't see any reason for random/urandom to do
it. In fact, it's a (trivial, harmless) timing information leak. And
obviously, it generates power- and flash-cycle wasting I/O, especially
if combined with something like hwrngd. Also, it breaks ubifs's

Signed-off-by: Matt Mackall <mpm@xxxxxxxxxxx>

diff -r 29db0c391ce8 drivers/char/random.c
--- a/drivers/char/random.c Sun Jan 17 11:01:16 2010 -0800
+++ b/drivers/char/random.c Mon Jan 25 23:32:00 2010 -0600
@@ -1051,12 +1051,6 @@
/* like a named pipe */
- /*
- * If we gave the user some bytes, update the access time.
- */
- if (count)
- file_accessed(file);
return (count ? count : retval);
@@ -1116,8 +1110,6 @@
if (ret)
return ret;
- inode->i_mtime = current_fs_time(inode->i_sb);
- mark_inode_dirty(inode);
return (ssize_t)count;
It may brake other FSes expectations, theoretically, as well.

Anyway, I'm perfectly fine if this is removed.

Jeff, could you please try Matt's patch and report back if you still
have issues or not. If no, you can use this as a temporary work-around
until a proper fix hits upstream or ubifs-2.6.git.
Matt's patch did not compile as written. I tried to implement what I think he was trying to do and created this patch (it seems to match the guts of what inode_setattr() was looking for):

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 8258982..70f16c7 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1108,6 +1108,7 @@ static ssize_t random_write(struct file *file, const char __user *buffer,
size_t ret;
struct inode *inode = file->f_path.dentry->d_inode;
+ struct iattr attr;

ret = write_pool(&blocking_pool, buffer, count);
if (ret)
@@ -1116,8 +1117,12 @@ static ssize_t random_write(struct file *file, const char __user *buffer,
if (ret)
return ret;

- inode->i_mtime = current_fs_time(inode->i_sb);
- mark_inode_dirty(inode);
+ attr.ia_mtime = current_fs_time(inode->i_sb);
+ attr.ia_valid = ATTR_MTIME;
+ ret = inode_setattr(inode, &attr);
+ if (ret)
+ return ret;
return (ssize_t)count;

However, this patch does not fix the problem. I still see the same errors. Matt, is this what you were trying to do?

That doesn't look anything like my patch? And mine was test compiled.

Ahh, you would be right. I mixed up authors. My bad. ;)

Matt's patch that removes the offending code works fine.

Artem's patch that tries to fix the offending code (and does not compile as posted) does not work.

Jeff Angielski
The PTR Group
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