linux.git/include/linux/dcache.h, branch v3.15

dentry_kill(): don't try to remove from shrink list

2014-05-01T14:30:00+00:00

If the victim in on the shrink list, don't remove it from there.
If shrink_dentry_list() manages to remove it from the list before
we are done - fine, we'll just free it as usual.  If not - mark
it with new flag (DCACHE_MAY_FREE) and leave it there.

Eventually, shrink_dentry_list() will get to it, remove the sucker
from shrink list and call dentry_kill(dentry, 0).  Which is where
we'll deal with freeing.

Since now dentry_kill(dentry, 0) may happen after or during
dentry_kill(dentry, 1), we need to recognize that (by seeing
DCACHE_DENTRY_KILLED already set), unlock everything
and either free the sucker (in case DCACHE_MAY_FREE has been
set) or leave it for ongoing dentry_kill(dentry, 1) to deal with.

Signed-off-by: Al Viro

vfs: add cross-rename

2014-04-01T15:08:43+00:00

If flags contain RENAME_EXCHANGE then exchange source and destination files.
There's no restriction on the type of the files; e.g. a directory can be
exchanged with a symlink.

Signed-off-by: Miklos Szeredi 
Reviewed-by: Jan Kara 
Reviewed-by: J. Bruce Fields

vfs: add d_is_dir()

2014-04-01T15:08:41+00:00

Add d_is_dir(dentry) helper which is analogous to S_ISDIR().

To avoid confusion, rename d_is_directory() to d_can_lookup().

Signed-off-by: Miklos Szeredi 
Reviewed-by: J. Bruce Fields

dcache: allow word-at-a-time name hashing with big-endian CPUs

2013-12-12T18:39:01+00:00

When explicitly hashing the end of a string with the word-at-a-time
interface, we have to be careful which end of the word we pick up.

On big-endian CPUs, the upper-bits will contain the data we're after, so
ensure we generate our masks accordingly (and avoid hashing whatever
random junk may have been sitting after the string).

This patch adds a new dcache helper, bytemask_from_count, which creates
a mask appropriate for the CPU endianness.

Cc: Al Viro 
Signed-off-by: Will Deacon 
Signed-off-by: Linus Torvalds

VFS: Put a small type field into struct dentry::d_flags

2013-11-09T05:16:30+00:00

Put a type field into struct dentry::d_flags to indicate if the dentry is one
of the following types that relate particularly to pathwalk:

	Miss (negative dentry)
	Directory
	"Automount" directory (defective - no i_op->lookup())
	Symlink
	Other (regular, socket, fifo, device)

The type field is set to one of the first five types on a dentry by calls to
__d_instantiate() and d_obtain_alias() from information in the inode (if one is
given).

The type is cleared by dentry_unlink_inode() when it reconstitutes an existing
dentry as a negative dentry.

Accessors provided are:

	d_set_type(dentry, type)
	d_is_directory(dentry)
	d_is_autodir(dentry)
	d_is_symlink(dentry)
	d_is_file(dentry)
	d_is_negative(dentry)
	d_is_positive(dentry)

A bunch of checks in pathname resolution switched to those.

Signed-off-by: David Howells 
Signed-off-by: Al Viro

vfs: introduce d_instantiate_no_diralias()

2013-10-25T03:41:37+00:00

...which just returns -EBUSY if a directory alias would be created.

This is to be used by fuse mkdir to make sure that a buggy or malicious
userspace filesystem doesn't do anything nasty.  Previously fuse used a
private mutex for this purpose, which can now go away.

Signed-off-by: Miklos Szeredi

super: fix calculation of shrinkable objects for small numbers

2013-09-10T22:56:29+00:00

The sysctl knob sysctl_vfs_cache_pressure is used to determine which
percentage of the shrinkable objects in our cache we should actively try
to shrink.

It works great in situations in which we have many objects (at least more
than 100), because the aproximation errors will be negligible.  But if
this is not the case, specially when total_objects < 100, we may end up
concluding that we have no objects at all (total / 100 = 0, if total <
100).

This is certainly not the biggest killer in the world, but may matter in
very low kernel memory situations.

Signed-off-by: Glauber Costa 
Reviewed-by: Carlos Maiolino 
Acked-by: KAMEZAWA Hiroyuki 
Acked-by: Mel Gorman 
Cc: Dave Chinner 
Cc: Al Viro 
Cc: "Theodore Ts'o" 
Cc: Adrian Hunter 
Cc: Al Viro 
Cc: Artem Bityutskiy 
Cc: Arve Hjønnevåg 
Cc: Carlos Maiolino 
Cc: Christoph Hellwig 
Cc: Chuck Lever 
Cc: Daniel Vetter 
Cc: David Rientjes 
Cc: Gleb Natapov 
Cc: Greg Thelen 
Cc: J. Bruce Fields 
Cc: Jan Kara 
Cc: Jerome Glisse 
Cc: John Stultz 
Cc: KAMEZAWA Hiroyuki 
Cc: Kent Overstreet 
Cc: Kirill A. Shutemov 
Cc: Marcelo Tosatti 
Cc: Mel Gorman 
Cc: Steven Whitehouse 
Cc: Thomas Hellstrom 
Cc: Trond Myklebust 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

fs: bump inode and dentry counters to long

2013-09-10T22:56:29+00:00

This series reworks our current object cache shrinking infrastructure in
two main ways:

 * Noticing that a lot of users copy and paste their own version of LRU
   lists for objects, we put some effort in providing a generic version.
   It is modeled after the filesystem users: dentries, inodes, and xfs
   (for various tasks), but we expect that other users could benefit in
   the near future with little or no modification.  Let us know if you
   have any issues.

 * The underlying list_lru being proposed automatically and
   transparently keeps the elements in per-node lists, and is able to
   manipulate the node lists individually.  Given this infrastructure, we
   are able to modify the up-to-now hammer called shrink_slab to proceed
   with node-reclaim instead of always searching memory from all over like
   it has been doing.

Per-node lru lists are also expected to lead to less contention in the lru
locks on multi-node scans, since we are now no longer fighting for a
global lock.  The locks usually disappear from the profilers with this
change.

Although we have no official benchmarks for this version - be our guest to
independently evaluate this - earlier versions of this series were
performance tested (details at
http://permalink.gmane.org/gmane.linux.kernel.mm/100537) yielding no
visible performance regressions while yielding a better qualitative
behavior in NUMA machines.

With this infrastructure in place, we can use the list_lru entry point to
provide memcg isolation and per-memcg targeted reclaim.  Historically,
those two pieces of work have been posted together.  This version presents
only the infrastructure work, deferring the memcg work for a later time,
so we can focus on getting this part tested.  You can see more about the
history of such work at http://lwn.net/Articles/552769/

Dave Chinner (18):
  dcache: convert dentry_stat.nr_unused to per-cpu counters
  dentry: move to per-sb LRU locks
  dcache: remove dentries from LRU before putting on dispose list
  mm: new shrinker API
  shrinker: convert superblock shrinkers to new API
  list: add a new LRU list type
  inode: convert inode lru list to generic lru list code.
  dcache: convert to use new lru list infrastructure
  list_lru: per-node list infrastructure
  shrinker: add node awareness
  fs: convert inode and dentry shrinking to be node aware
  xfs: convert buftarg LRU to generic code
  xfs: rework buffer dispose list tracking
  xfs: convert dquot cache lru to list_lru
  fs: convert fs shrinkers to new scan/count API
  drivers: convert shrinkers to new count/scan API
  shrinker: convert remaining shrinkers to count/scan API
  shrinker: Kill old ->shrink API.

Glauber Costa (7):
  fs: bump inode and dentry counters to long
  super: fix calculation of shrinkable objects for small numbers
  list_lru: per-node API
  vmscan: per-node deferred work
  i915: bail out earlier when shrinker cannot acquire mutex
  hugepage: convert huge zero page shrinker to new shrinker API
  list_lru: dynamically adjust node arrays

This patch:

There are situations in very large machines in which we can have a large
quantity of dirty inodes, unused dentries, etc.  This is particularly true
when umounting a filesystem, where eventually since every live object will
eventually be discarded.

Dave Chinner reported a problem with this while experimenting with the
shrinker revamp patchset.  So we believe it is time for a change.  This
patch just moves int to longs.  Machines where it matters should have a
big long anyway.

Signed-off-by: Glauber Costa 
Cc: Dave Chinner 
Cc: "Theodore Ts'o" 
Cc: Adrian Hunter 
Cc: Al Viro 
Cc: Artem Bityutskiy 
Cc: Arve Hjønnevåg 
Cc: Carlos Maiolino 
Cc: Christoph Hellwig 
Cc: Chuck Lever 
Cc: Daniel Vetter 
Cc: Dave Chinner 
Cc: David Rientjes 
Cc: Gleb Natapov 
Cc: Greg Thelen 
Cc: J. Bruce Fields 
Cc: Jan Kara 
Cc: Jerome Glisse 
Cc: John Stultz 
Cc: KAMEZAWA Hiroyuki 
Cc: Kent Overstreet 
Cc: Kirill A. Shutemov 
Cc: Marcelo Tosatti 
Cc: Mel Gorman 
Cc: Steven Whitehouse 
Cc: Thomas Hellstrom 
Cc: Trond Myklebust 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

vfs: reorganize dput() memory accesses

2013-09-08T20:26:18+00:00

This is me being a bit OCD after all the dentry optimization work this
merge window: profiles end up showing 'dput()' as a rather expensive
operation, and there were two unrelated bad reasons for that.

The first reason was reading d_lockref.count for debugging purposes,
which touches the lockref cacheline (for reads) before really need to.
More importantly, the debugging test in question is _wrong_, and has
hidden bugs.  It's true that we can only sleep when the count goes down
to zero, but the test as-is hides the much more subtle bug that happens
if we race with somebody else deleting the file.

Anyway we _will_ touch that cacheline, but let's do it for a write and
in the right routine (ie in "lockref_put_or_lock()") which annotates the
costs better.  So remove the misleading debug code.

The other was an unnecessary access to the cacheline that contains the
d_lru list, just to check whether we already were on the LRU list or
not.  This is exactly what we have d_flags for, so that we can avoid
touching extra cache lines for the common case.  So just add another bit
for "is this dentry on the LRU".

Finally, mark the tests properly likely/unlikely, so that the common
fast-paths are dense in the instruction stream.

This makes the profiles look much saner.

Signed-off-by: Linus Torvalds

constify dcache.c inlined helpers where possible

2013-09-05T20:23:55+00:00

Signed-off-by: Al Viro