linux-stable.git/fs/inode.c, branch linux-2.6.28.y

fs: new inode i_state corruption fix

2009-03-17T00:32:18+00:00

commit 7ef0d7377cb287e08f3ae94cebc919448e1f5dff upstream.

There was a report of a data corruption
http://lkml.org/lkml/2008/11/14/121.  There is a script included to
reproduce the problem.

During testing, I encountered a number of strange things with ext3, so I
tried ext2 to attempt to reduce complexity of the problem.  I found that
fsstress would quickly hang in wait_on_inode, waiting for I_LOCK to be
cleared, even though instrumentation showed that unlock_new_inode had
already been called for that inode.  This points to memory scribble, or
synchronisation problme.

i_state of I_NEW inodes is not protected by inode_lock because other
processes are not supposed to touch them until I_LOCK (and I_NEW) is
cleared.  Adding WARN_ON(inode->i_state & I_NEW) to sites where we modify
i_state revealed that generic_sync_sb_inodes is picking up new inodes from
the inode lists and passing them to __writeback_single_inode without
waiting for I_NEW.  Subsequently modifying i_state causes corruption.  In
my case it would look like this:

CPU0                            CPU1
unlock_new_inode()              __sync_single_inode()
 reg <- inode->i_state
 reg -> reg & ~(I_LOCK|I_NEW)   reg <- inode->i_state
 reg -> inode->i_state          reg -> reg | I_SYNC
                                reg -> inode->i_state

Non-atomic RMW on CPU1 overwrites CPU0 store and sets I_LOCK|I_NEW again.

Fix for this is rather than wait for I_NEW inodes, just skip over them:
inodes concurrently being created are not subject to data integrity
operations, and should not significantly contribute to dirty memory
either.

After this change, I'm unable to reproduce any of the added warnings or
hangs after ~1hour of running.  Previously, the new warnings would start
immediately and hang would happen in under 5 minutes.

I'm also testing on ext3 now, and so far no problems there either.  I
don't know whether this fixes the problem reported above, but it fixes a
real problem for me.

Cc: "Jorge Boncompte [DTI2]" 
Reported-by: Adrian Hunter 
Cc: Jan Kara 
Signed-off-by: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fs/inode.c: properly init address_space->writeback_index

2008-08-15T15:35:44+00:00

write_cache_pages() uses i_mapping->writeback_index to pick up where it
left off the last time a given inode was found by pdflush or
balance_dirty_pages (or anyone else who sets wbc->range_cyclic)

alloc_inode() should set it to a sane value so that writeback doesn't
start in the middle of a file.  It is somewhat difficult to notice the bug
since write_cache_pages will loop around to the start of the file and the
elevator helps hide the resulting seeks.

For whatever reason, Btrfs hits this often.  Unpatched, untarring 30
copies of the linux kernel in series runs at 47MB/s on a single sata
drive.  With this fix, it jumps to 62MB/s.

Signed-off-by: Chris Mason 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

SL*B: drop kmem cache argument from constructor

2008-07-26T19:00:07+00:00

Kmem cache passed to constructor is only needed for constructors that are
themselves multiplexeres.  Nobody uses this "feature", nor does anybody uses
passed kmem cache in non-trivial way, so pass only pointer to object.

Non-trivial places are:
	arch/powerpc/mm/init_64.c
	arch/powerpc/mm/hugetlbpage.c

This is flag day, yes.

Signed-off-by: Alexey Dobriyan 
Acked-by: Pekka Enberg 
Acked-by: Christoph Lameter 
Cc: Jon Tollefson 
Cc: Nick Piggin 
Cc: Matt Mackall 
[akpm@linux-foundation.org: fix arch/powerpc/mm/hugetlbpage.c]
[akpm@linux-foundation.org: fix mm/slab.c]
[akpm@linux-foundation.org: fix ubifs]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: spinlock tree_lock

2008-07-26T19:00:06+00:00

mapping->tree_lock has no read lockers.  convert the lock from an rwlock
to a spinlock.

Signed-off-by: Nick Piggin 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Hugh Dickins 
Cc: "Paul E. McKenney" 
Reviewed-by: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

VFS: fix unused variable warning

2008-05-06T20:13:37+00:00

Commit 33dcdac2df54e66c447ae03f58c95c7251aa5649 ("kill ->put_inode")
removed the final use of i_op->put_inode, but left the now totally
unused "op" variable in iput().

Get rid of it.

Signed-off-by: Linus Torvalds

[PATCH] kill ->put_inode

2008-05-06T17:45:34+00:00

And with that last patch to affs killing the last put_inode instance we
can finally, after many years of transition kill this racy and awkward
interface.

(It's kinda funny that even the description in
Documentation/filesystems/vfs.txt was entirely wrong..)

Also remove a very misleading comment above the defintion of
struct super_operations.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

fs/inode.c: use hlist_for_each_entry()

2008-04-29T15:06:06+00:00

fs/inode.c: use hlist_for_each_entry() in find_inode() and find_inode_fast()

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Matthias Kaehlcke 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] r/o bind mounts: write count for file_update_time()

2008-04-19T04:29:24+00:00

Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dave Hansen 
Signed-off-by: Al Viro

[PATCH] r/o bind mounts: write counts for touch_atime()

2008-04-19T04:29:23+00:00

Remove handling of NULL mnt while we are at it - that can't happen these days.

Acked-by: Al Viro 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Dave Hansen 
Signed-off-by: Al Viro

iget: remove iget() and the read_inode() super op as being obsolete

2008-02-07T16:42:29+00:00

Remove the old iget() call and the read_inode() superblock operation it uses
as these are really obsolete, and the use of read_inode() does not produce
proper error handling (no distinction between ENOMEM and EIO when marking an
inode bad).

Furthermore, this removes the temptation to use iget() to find an inode by
number in a filesystem from code outside that filesystem.

iget_locked() should be used instead.  A new function is added in an earlier
patch (iget_failed) that is to be called to mark an inode as bad, unlock it
and release it should the get routine fail.  Mark iget() and read_inode() as
being obsolete and remove references to them from the documentation.

Typically a filesystem will be modified such that the read_inode function
becomes an internal iget function, for example the following:

	void thingyfs_read_inode(struct inode *inode)
	{
		...
	}

would be changed into something like:

	struct inode *thingyfs_iget(struct super_block *sp, unsigned long ino)
	{
		struct inode *inode;
		int ret;

		inode = iget_locked(sb, ino);
		if (!inode)
			return ERR_PTR(-ENOMEM);
		if (!(inode->i_state & I_NEW))
			return inode;

		...
		unlock_new_inode(inode);
		return inode;
	error:
		iget_failed(inode);
		return ERR_PTR(ret);
	}

and then thingyfs_iget() would be called rather than iget(), for example:

	ret = -EINVAL;
	inode = iget(sb, ino);
	if (!inode || is_bad_inode(inode))
		goto error;

becomes:

	inode = thingyfs_iget(sb, ino);
	if (IS_ERR(inode)) {
		ret = PTR_ERR(inode);
		goto error;
	}

Note that is_bad_inode() does not need to be called.  The error returned by
thingyfs_iget() should render it unnecessary.

Signed-off-by: David Howells 
Acked-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds