linux/fs/squashfs
Nick Piggin fa0d7e3de6 fs: icache RCU free inodes
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 <npiggin@kernel.dk>
2011-01-07 17:50:26 +11:00
..
block.c squashfs: fix potential buffer over-run on 4K block file systems 2010-04-25 02:09:05 +01:00
cache.c Squashfs: factor out remaining zlib dependencies into separate wrapper file 2010-01-20 21:47:47 +00:00
decompressor.c Squashfs: Add LZO compression support 2010-08-05 02:29:59 +01:00
decompressor.h Squashfs: add a decompressor framework 2010-01-20 21:47:47 +00:00
dir.c llseek: automatically add .llseek fop 2010-10-15 15:53:27 +02:00
export.c Squashfs: factor out remaining zlib dependencies into separate wrapper file 2010-01-20 21:47:47 +00:00
file.c Squashfs: factor out remaining zlib dependencies into separate wrapper file 2010-01-20 21:47:47 +00:00
fragment.c Squashfs: factor out remaining zlib dependencies into separate wrapper file 2010-01-20 21:47:47 +00:00
id.c Squashfs: factor out remaining zlib dependencies into separate wrapper file 2010-01-20 21:47:47 +00:00
inode.c squashfs: add xattr support configure option 2010-05-17 19:54:07 +01:00
Kconfig Squashfs: update Kconfig and documentation for LZO 2010-08-05 23:42:54 +01:00
lzo_wrapper.c Squashfs: fix block size use in LZO decompressor 2010-08-05 04:51:50 +01:00
Makefile Squashfs: Add LZO compression support 2010-08-05 02:29:59 +01:00
namei.c squashfs: add xattr support configure option 2010-05-17 19:54:07 +01:00
squashfs_fs_i.h squashfs: add support for xattr reading 2010-05-17 19:54:06 +01:00
squashfs_fs_sb.h squashfs: add xattr id support 2010-05-17 19:54:05 +01:00
squashfs_fs.h Squashfs: fix checkpatch.pl warnings 2010-08-08 22:29:33 +00:00
squashfs.h Squashfs: fix filename typo 2010-08-05 23:52:53 +01:00
super.c fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
symlink.c squashfs: add xattr support configure option 2010-05-17 19:54:07 +01:00
xattr_id.c Squashfs: fix function prototype 2010-10-28 17:44:19 +01:00
xattr.c Squashfs: fix use of __le64 annotated variable 2010-10-28 17:44:11 +01:00
xattr.h Squashfs: fix function prototype 2010-10-28 17:44:19 +01:00
zlib_wrapper.c squashfs: fix locking bug in zlib wrapper 2010-04-23 02:54:54 +01:00