linux-toradex.git/fs/qnx4, branch v3.0.43

block: remove per-queue plugging

2011-03-10T07:52:07+00:00

Code has been converted over to the new explicit on-stack plugging,
and delay users have been converted to use the new API for that.
So lets kill off the old plugging along with aops->sync_page().

Signed-off-by: Jens Axboe

fs: icache RCU free inodes

2011-01-07T06:50:26+00:00

RCU free the struct inode. This will allow:

- Subsequent store-free path walking patch. The inode must be consulted for
  permissions when walking, so an RCU inode reference is a must.
- sb_inode_list_lock to be moved inside i_lock because sb list walkers who want
  to take i_lock no longer need to take sb_inode_list_lock to walk the list in
  the first place. This will simplify and optimize locking.
- Could remove some nested trylock loops in dcache code
- Could potentially simplify things a bit in VM land. Do not need to take the
  page lock to follow page->mapping.

The downsides of this is the performance cost of using RCU. In a simple
creat/unlink microbenchmark, performance drops by about 10% due to inability to
reuse cache-hot slab objects. As iterations increase and RCU freeing starts
kicking over, this increases to about 20%.

In cases where inode lifetimes are longer (ie. many inodes may be allocated
during the average life span of a single inode), a lot of this cache reuse is
not applicable, so the regression caused by this patch is smaller.

The cache-hot regression could largely be avoided by using SLAB_DESTROY_BY_RCU,
however this adds some complexity to list walking and store-free path walking,
so I prefer to implement this at a later date, if it is shown to be a win in
real situations. I haven't found a regression in any non-micro benchmark so I
doubt it will be a problem.

Signed-off-by: Nick Piggin

new helper: mount_bdev()

2010-10-29T08:16:13+00:00

... and switch of the obvious get_sb_bdev() users to ->mount()

Signed-off-by: Al Viro

BKL: remove BKL from qnx4

2010-10-21T16:48:04+00:00

All uses of the BKL in qnx4 were the result of a pushdown into
code that doesn't really need it. As Christoph points out, this
is a read-only file system, which eliminates most of the races in
readdir/lookup.

Signed-off-by: Arnd Bergmann 
Acked-by: Anders Larsen 
Cc: Christoph Hellwig

BKL: Explicitly add BKL around get_sb/fill_super

2010-10-04T19:10:10+00:00

This patch is a preparation necessary to remove the BKL from do_new_mount().
It explicitly adds calls to lock_kernel()/unlock_kernel() around
get_sb/fill_super operations for filesystems that still uses the BKL.

I've read through all the code formerly covered by the BKL inside
do_kern_mount() and have satisfied myself that it doesn't need the BKL
any more.

do_kern_mount() is already called without the BKL when mounting the rootfs
and in nfsctl. do_kern_mount() calls vfs_kern_mount(), which is called
from various places without BKL: simple_pin_fs(), nfs_do_clone_mount()
through nfs_follow_mountpoint(), afs_mntpt_do_automount() through
afs_mntpt_follow_link(). Both later functions are actually the filesystems
follow_link inode operation. vfs_kern_mount() is calling the specified
get_sb function and lets the filesystem do its job by calling the given
fill_super function.

Therefore I think it is safe to push down the BKL from the VFS to the
low-level filesystems get_sb/fill_super operation.

[arnd: do not add the BKL to those file systems that already
       don't use it elsewhere]

Signed-off-by: Jan Blunck 
Signed-off-by: Arnd Bergmann 
Cc: Matthew Wilcox 
Cc: Christoph Hellwig

get rid of cont_write_begin_newtrunc

2010-08-09T20:47:31+00:00

Move the call to vmtruncate to get rid of accessive blocks to the callers
in preparation of the new truncate sequence and rename the non-truncating
version to cont_write_begin.

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

rename the generic fsync implementations

2010-05-28T02:06:06+00:00

We don't name our generic fsync implementations very well currently.
The no-op implementation for in-memory filesystems currently is called
simple_sync_file which doesn't make too much sense to start with,
the the generic one for simple filesystems is called simple_fsync
which can lead to some confusion.

This patch renames the generic file fsync method to generic_file_fsync
to match the other generic_file_* routines it is supposed to be used
with, and the no-op implementation to noop_fsync to make it obvious
what to expect.  In addition add some documentation for both methods.

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

fs/: do not fallback to default_llseek() when readdir() uses BKL

2010-05-27T16:12:56+00:00

Do not use the fallback default_llseek() if the readdir operation of the
filesystem still uses the big kernel lock.

Since llseek() modifies
file->f_pos of the directory directly it may need locking to not confuse
readdir which usually uses file->f_pos directly as well

Since the special characteristics of the BKL (unlocked on schedule) are
not necessary in this case, the inode mutex can be used for locking as
provided by generic_file_llseek().  This is only possible since all
filesystems, except reiserfs, either use a directory as a flat file or
with disk address offsets.  Reiserfs on the other hand uses a 32bit hash
off the filename as the offset so generic_file_llseek() can get used as
well since the hash is always smaller than sb->s_maxbytes (= (512 << 32) -
blocksize).

Signed-off-by: Jan Blunck 
Acked-by: Jan Kara 
Acked-by: Anders Larsen 
Cc: Frederic Weisbecker 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/qnx4: decrement sizeof size in strncmp

2010-02-04T10:55:46+00:00

As an identical match is wanted in this case, strcmp can be used instead.

The semantic match that lead to detecting this problem is as follows:
(http://coccinelle.lip6.fr/)

// 
@@
expression foo;
constant char *abc;
@@

*strncmp(foo, abc, sizeof(abc))
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Anders Larsen 
Signed-off-by: Jiri Kosina

qnx4: use hweight8

2009-12-16T15:20:18+00:00

Use hweight8 instead of counting for each bit

Signed-off-by: Akinobu Mita 
Acked-by: Anders Larsen 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds