linux.git/fs/inode.c, branch v2.6.23

mm: Remove slab destructors from kmem_cache_create().

2007-07-20T01:11:58+00:00

Slab destructors were no longer supported after Christoph's
c59def9f222d44bb7e2f0a559f2906191a0862d7 change. They've been
BUGs for both slab and slub, and slob never supported them
either.

This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).

Signed-off-by: Paul Mundt

mm: clean up and kernelify shrinker registration

2007-07-17T17:23:00+00:00

I can never remember what the function to register to receive VM pressure
is called.  I have to trace down from __alloc_pages() to find it.

It's called "set_shrinker()", and it needs Your Help.

1) Don't hide struct shrinker.  It contains no magic.
2) Don't allocate "struct shrinker".  It's not helpful.
3) Call them "register_shrinker" and "unregister_shrinker".
4) Call the function "shrink" not "shrinker".
5) Reduce the 17 lines of waffly comments to 13, but document it properly.

Signed-off-by: Rusty Russell 
Cc: David Chinner 
Cc: Trond Myklebust 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Add __GFP_MOVABLE for callers to flag allocations from high memory that may be migrated

2007-07-17T17:22:59+00:00

It is often known at allocation time whether a page may be migrated or not.
This patch adds a flag called __GFP_MOVABLE and a new mask called
GFP_HIGH_MOVABLE.  Allocations using the __GFP_MOVABLE can be either migrated
using the page migration mechanism or reclaimed by syncing with backing
storage and discarding.

An API function very similar to alloc_zeroed_user_highpage() is added for
__GFP_MOVABLE allocations called alloc_zeroed_user_highpage_movable().  The
flags used by alloc_zeroed_user_highpage() are not changed because it would
change the semantics of an existing API.  After this patch is applied there
are no in-kernel users of alloc_zeroed_user_highpage() so it probably should
be marked deprecated if this patch is merged.

Note that this patch includes a minor cleanup to the use of __GFP_ZERO in
shmem.c to keep all flag modifications to inode->mapping in the
shmem_dir_alloc() helper function.  This clean-up suggestion is courtesy of
Hugh Dickens.

Additional credit goes to Christoph Lameter and Linus Torvalds for shaping the
concept.  Credit to Hugh Dickens for catching issues with shmem swap vector
and ramfs allocations.

[akpm@linux-foundation.org: build fix]
[hugh@veritas.com: __GFP_ZERO cleanup]
Signed-off-by: Mel Gorman 
Cc: Andy Whitcroft 
Cc: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Remove SLAB_CTOR_CONSTRUCTOR

2007-05-17T12:23:04+00:00

SLAB_CTOR_CONSTRUCTOR is always specified. No point in checking it.

Signed-off-by: Christoph Lameter 
Cc: David Howells 
Cc: Jens Axboe 
Cc: Steven French 
Cc: Michael Halcrow 
Cc: OGAWA Hirofumi 
Cc: Miklos Szeredi 
Cc: Steven Whitehouse 
Cc: Roman Zippel 
Cc: David Woodhouse 
Cc: Dave Kleikamp 
Cc: Trond Myklebust 
Cc: "J. Bruce Fields" 
Cc: Anton Altaparmakov 
Cc: Mark Fasheh 
Cc: Paul Mackerras 
Cc: Christoph Hellwig 
Cc: Jan Kara 
Cc: David Chinner 
Cc: "David S. Miller" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

inode numbering: make static counters in new_inode and iunique be 32 bits

2007-05-08T18:15:16+00:00

The problems are:

- on filesystems w/o permanent inode numbers, i_ino values can be larger
  than 32 bits, which can cause problems for some 32 bit userspace programs on
  a 64 bit kernel.  We can't do anything for filesystems that have actual
  >32-bit inode numbers, but on filesystems that generate i_ino values on the
  fly, we should try to have them fit in 32 bits.  We could trivially fix this
  by making the static counters in new_inode and iunique 32 bits, but...

- many filesystems call new_inode and assume that the i_ino values they are
  given are unique.  They are not guaranteed to be so, since the static
  counter can wrap.  This problem is exacerbated by the fix for #1.

- after allocating a new inode, some filesystems call iunique to try to get
  a unique i_ino value, but they don't actually add their inodes to the
  hashtable, and so they're still not guaranteed to be unique if that counter
  wraps.

This patch set takes the simpler approach of simply using iunique and hashing
the inodes afterward.  Christoph H.  previously mentioned that he thought that
this approach may slow down lookups for filesystems that currently hash their
inodes.

The questions are:

1) how much would this slow down lookups for these filesystems?
2) is it enough to justify adding more infrastructure to avoid it?

What might be best is to start with this approach and then only move to using
IDR or some other scheme if these extra inodes in the hashtable prove to be
problematic.

I've done some cursory testing with this patch and the overhead of hashing and
unhashing the inodes with pipefs is pretty low -- just a few seconds of system
time added on to the creation and destruction of 10 million pipes (very
similar to the overhead that the IDR approach would add).

The hard thing to measure is what effect this has on other filesystems. I'm
open to ways to try and gauge this.

Again, I've only converted pipefs as an example. If this approach is
acceptable then I'll start work on patches to convert other filesystems.

With a pretty-much-worst-case microbenchmark provided by Eric Dumazet
:

hashing patch (pipebench):
sys     1m15.329s
sys     1m16.249s
sys     1m17.169s

unpatched (pipebench):
sys     1m9.836s
sys     1m12.541s
sys     1m14.153s

Which works out to 1.05642174294555027017.  So ~5-6% slowdown.

This patch:

When a 32-bit program that was not compiled with large file offsets does a
stat and gets a st_ino value back that won't fit in the 32 bit field, glibc
(correctly) generates an EOVERFLOW error.  We can't do anything about fs's
with larger permanent inode numbers, but when we generate them on the fly, we
ought to try and have them fit within a 32 bit field.

This patch takes the first step toward this by making the static counters in
these two functions be 32 bits.

[jlayton@redhat.com: mention that it's only the case for 32bit, non-LFS stat]
Signed-off-by: Jeff Layton 
Cc: Christoph Hellwig 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Introduce a handy list_first_entry macro

2007-05-08T18:15:11+00:00

There are many places in the kernel where the construction like

   foo = list_entry(head->next, struct foo_struct, list);

are used.
The code might look more descriptive and neat if using the macro

   list_first_entry(head, type, member) \
             list_entry((head)->next, type, member)

Here is the macro itself and the examples of its usage in the generic code.
 If it will turn out to be useful, I can prepare the set of patches to
inject in into arch-specific code, drivers, networking, etc.

Signed-off-by: Pavel Emelianov 
Signed-off-by: Kirill Korotaev 
Cc: Randy Dunlap 
Cc: Andi Kleen 
Cc: Zach Brown 
Cc: Davide Libenzi 
Cc: John McCutchan 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: john stultz 
Cc: Ram Pai 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

make iunique use a do/while loop rather than its obscure goto loop

2007-05-08T18:15:10+00:00

A while back, Christoph mentioned that he thought that iunique ought to be
cleaned up to use a more conventional loop construct. This patch does that,
turning the strange goto loop into a do/while.

Signed-off-by: Jeff Layton 
Cc: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vfs: remove superflous sb == NULL checks

2007-05-08T18:15:02+00:00

inode->i_sb is always set, not need to check for it.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

slab allocators: Remove SLAB_DEBUG_INITIAL flag

2007-05-07T19:12:57+00:00

I have never seen a use of SLAB_DEBUG_INITIAL.  It is only supported by
SLAB.

I think its purpose was to have a callback after an object has been freed
to verify that the state is the constructor state again?  The callback is
performed before each freeing of an object.

I would think that it is much easier to check the object state manually
before the free.  That also places the check near the code object
manipulation of the object.

Also the SLAB_DEBUG_INITIAL callback is only performed if the kernel was
compiled with SLAB debugging on.  If there would be code in a constructor
handling SLAB_DEBUG_INITIAL then it would have to be conditional on
SLAB_DEBUG otherwise it would just be dead code.  But there is no such code
in the kernel.  I think SLUB_DEBUG_INITIAL is too problematic to make real
use of, difficult to understand and there are easier ways to accomplish the
same effect (i.e.  add debug code before kfree).

There is a related flag SLAB_CTOR_VERIFY that is frequently checked to be
clear in fs inode caches.  Remove the pointless checks (they would even be
pointless without removeal of SLAB_DEBUG_INITIAL) from the fs constructors.

This is the last slab flag that SLUB did not support.  Remove the check for
unimplemented flags from SLUB.

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Mark struct super_operations const

2007-02-12T17:48:47+00:00

This patch is inspired by Arjan's "Patch series to mark struct
file_operations and struct inode_operations const".

Compile tested with gcc & sparse.

Signed-off-by: Josef 'Jeff' Sipek 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds