linux-toradex.git/fs/dcache.c, branch v3.3.5

vfs: fix d_ancestor() case in d_materialize_unique

2012-04-02T17:32:20+00:00

commit b18dafc86bb879d2f38a1743985d7ceb283c2f4d upstream.

In d_materialise_unique() there are 3 subcases to the 'aliased dentry'
case; in two subcases the inode i_lock is properly released but this
does not occur in the -ELOOP subcase.

This seems to have been introduced by commit 1836750115f2 ("fix loop
checks in d_materialise_unique()").

Signed-off-by: Michel Lespinasse 
[ Added a comment, and moved the unlock to where we generate the -ELOOP,
  which seems to be more natural.

  You probably can't actually trigger this without a buggy network file
  server - d_materialize_unique() is for finding aliases on non-local
  filesystems, and the d_ancestor() case is for a hardlinked directory
  loop.

  But we should be robust in the case of such buggy servers anyway. ]
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

vfs: move dentry_cmp from to fs/dcache.c

2012-03-04T23:51:42+00:00

It's only used inside fs/dcache.c, and we're going to play games with it
for the word-at-a-time patches.  This time we really don't even want to
export it, because it really is an internal function to fs/dcache.c, and
has been since it was introduced.

Having it in that extremely hot header file (it's included in pretty
much everything, thanks to ) is a disaster for testing
different versions, and is utterly pointless.

We really should have some kind of header file diet thing, where we
figure out which parts of header files are really better off private and
only result in more expensive compiles.

Signed-off-by: Linus Torvalds

vfs: trivial __d_lookup_rcu() cleanups

2012-03-02T22:23:30+00:00

These don't change any semantics, but they clean up the code a bit and
mark some arguments appropriately 'const'.

They came up as I was doing the word-at-a-time dcache name accessor
code, and cleaning this up now allows me to send out a smaller relevant
interesting patch for the experimental stuff.

Signed-off-by: Linus Torvalds

vfs: fix panic in __d_lookup() with high dentry hashtable counts

2012-02-14T01:45:38+00:00

When the number of dentry cache hash table entries gets too high
(2147483648 entries), as happens by default on a 16TB system, use of a
signed integer in the dcache_init() initialization loop prevents the
dentry_hashtable from getting initialized, causing a panic in
__d_lookup().  Fix this in dcache_init() and similar areas.

Signed-off-by: Dimitri Sivanich 
Acked-by: David S. Miller 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client

2012-01-13T18:29:21+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: ensure prealloc_blob is in place when removing xattr
  rbd: initialize snap_rwsem in rbd_add()
  ceph: enable/disable dentry complete flags via mount option
  vfs: export symbol d_find_any_alias()
  ceph: always initialize the dentry in open_root_dentry()
  libceph: remove useless return value for osd_client __send_request()
  ceph: avoid iput() while holding spinlock in ceph_dir_fsync
  ceph: avoid useless dget/dput in encode_fh
  ceph: dereference pointer after checking for NULL
  crush: fix force for non-root TAKE
  ceph: remove unnecessary d_fsdata conditional checks
  ceph: Use kmemdup rather than duplicating its implementation

Fix up conflicts in fs/ceph/super.c (d_alloc_root() failure handling vs
always initialize the dentry in open_root_dentry)

vfs: export symbol d_find_any_alias()

2012-01-12T19:00:28+00:00

Ceph needs this.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Sage Weil

fix shrink_dcache_parent() livelock

2012-01-10T18:06:32+00:00

Two (or more) concurrent calls of shrink_dcache_parent() on the same dentry may
cause shrink_dcache_parent() to loop forever.

Here's what appears to happen:

1 - CPU0: select_parent(P) finds C and puts it on dispose list, returns 1

2 - CPU1: select_parent(P) locks P->d_lock

3 - CPU0: shrink_dentry_list() locks C->d_lock
   dentry_kill(C) tries to lock P->d_lock but fails, unlocks C->d_lock

4 - CPU1: select_parent(P) locks C->d_lock,
         moves C from dispose list being processed on CPU0 to the new
dispose list, returns 1

5 - CPU0: shrink_dentry_list() finds dispose list empty, returns

6 - Goto 2 with CPU0 and CPU1 switched

Basically select_parent() steals the dentry from shrink_dentry_list() and thinks
it found a new one, causing shrink_dentry_list() to think it's making progress
and loop over and over.

One way to trigger this is to make udev calls stat() on the sysfs file while it
is going away.

Having a file in /lib/udev/rules.d/ with only this one rule seems to the trick:

ATTR{vendor}=="0x8086", ATTR{device}=="0x10ca", ENV{PCI_SLOT_NAME}="%k", ENV{MATCHADDR}="$attr{address}", RUN+="/bin/true"

Then execute the following loop:

while true; do
        echo -bond0 > /sys/class/net/bonding_masters
        echo +bond0 > /sys/class/net/bonding_masters
        echo -bond1 > /sys/class/net/bonding_masters
        echo +bond1 > /sys/class/net/bonding_masters
done

One fix would be to check all callers and prevent concurrent calls to
shrink_dcache_parent().  But I think a better solution is to stop the
stealing behavior.

This patch adds a new dentry flag that is set when the dentry is added to the
dispose list.  The flag is cleared in dentry_lru_del() in case the dentry gets a
new reference just before being pruned.

If the dentry has this flag, select_parent() will skip it and let
shrink_dentry_list() retry pruning it.  With select_parent() skipping those
dentries there will not be the appearance of progress (new dentries found) when
there is none, hence shrink_dcache_parent() will not loop forever.

Set the flag is also set in prune_dcache_sb() for consistency as suggested by
Linus.

Signed-off-by: Miklos Szeredi 
CC: stable@vger.kernel.org
Signed-off-by: Al Viro

vfs: new helper - d_make_root()

2012-01-10T00:23:45+00:00

d_alloc_root() with iput() in case of allocation failure...

Signed-off-by: Al Viro

dcache: use a dispose list in select_parent

2012-01-10T00:22:52+00:00

select_parent currently abuses the dentry cache LRU to provide
cleanup features for child dentries that need to be freed. It moves
them to the tail of the LRU, then tells shrink_dcache_parent() to
calls __shrink_dcache_sb to unconditionally move them to a dispose
list (as DCACHE_REFERENCED is ignored). __shrink_dcache_sb() has to
relock the dentries to move them off the LRU onto the dispose list,
but otherwise does not touch the dentries that select_parent() moved
to the tail of the LRU. It then passses the dispose list to
shrink_dentry_list() which tries to free the dentries.

IOWs, the use of __shrink_dcache_sb() is superfluous - we can build
exactly the same list of dentries for disposal directly in
select_parent() and call shrink_dentry_list() instead of calling
__shrink_dcache_sb() to do that. This means that we avoid long holds
on the lru lock walking the LRU moving dentries to the dispose list
We also avoid the need to relock each dentry just to move it off the
LRU, reducing the numebr of times we lock each dentry to dispose of
them in shrink_dcache_parent() from 3 to 2 times.

Further, we remove one of the two callers of __shrink_dcache_sb().
This also means that __shrink_dcache_sb can be moved into back into
prune_dcache_sb() and we no longer have to handle referenced
dentries conditionally, simplifying the code.

Signed-off-by: Dave Chinner 
Signed-off-by: Linus Torvalds 
Signed-off-by: Al Viro

vfs: mnt_ns moved to struct mount

2012-01-04T03:57:09+00:00

Signed-off-by: Al Viro