linux-toradex.git/include/linux/writeback.h, branch v2.6.26-rc5

mm: bdi: export BDI attributes in sysfs

2008-04-30T15:29:49+00:00

Provide a place in sysfs (/sys/class/bdi) for the backing_dev_info object.
This allows us to see and set the various BDI specific variables.

In particular this properly exposes the read-ahead window for all relevant
users and /sys/block//queue/read_ahead_kb should be deprecated.

With patient help from Kay Sievers and Greg KH

[mszeredi@suse.cz]

 - split off NFS and FUSE changes into separate patches
 - document new sysfs attributes under Documentation/ABI
 - do bdi_class_init as a core_initcall, otherwise the "default" BDI
   won't be initialized
 - remove bdi_init_fmt macro, it's not used very much

[akpm@linux-foundation.org: fix ia64 warning]
Signed-off-by: Peter Zijlstra 
Cc: Kay Sievers 
Acked-by: Greg KH 
Cc: Trond Myklebust 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

writeback: speed up writeback of big dirty files

2008-02-05T17:44:19+00:00

After making dirty a 100M file, the normal behavior is to start the
writeback for all data after 30s delays.  But sometimes the following
happens instead:

	- after 30s:    ~4M
	- after 5s:     ~4M
	- after 5s:     all remaining 92M

Some analyze shows that the internal io dispatch queues goes like this:

		s_io            s_more_io
		-------------------------
	1)	100M,1K         0
	2)	1K              96M
	3)	0               96M
1) initial state with a 100M file and a 1K file

2) 4M written, nr_to_write <= 0, so write more

3) 1K written, nr_to_write > 0, no more writes(BUG)

nr_to_write > 0 in (3) fools the upper layer to think that data have all
been written out.  The big dirty file is actually still sitting in
s_more_io.  We cannot simply splice s_more_io back to s_io as soon as s_io
becomes empty, and let the loop in generic_sync_sb_inodes() continue: this
may starve newly expired inodes in s_dirty.  It is also not an option to
draw inodes from both s_more_io and s_dirty, an let the loop go on: this
might lead to live locks, and might also starve other superblocks in sync
time(well kupdate may still starve some superblocks, that's another bug).

We have to return when a full scan of s_io completes.  So nr_to_write > 0
does not necessarily mean that "all data are written".  This patch
introduces a flag writeback_control.more_io to indicate that more io should
be done.  With it the big dirty file no longer has to wait for the next
kupdate invokation 5s later.

In sync_sb_inodes() we only set more_io on super_blocks we actually
visited.  This avoids the interaction between two pdflush deamons.

Also in __sync_single_inode() we don't blindly keep requeuing the io if the
filesystem cannot progress.  Failing to do so may lead to 100% iowait.

Tested-by: Mike Snitzer 
Signed-off-by: Fengguang Wu 
Cc: Michael Rubin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page-writeback: highmem_is_dirtyable option

2008-02-05T17:44:18+00:00

Add vm.highmem_is_dirtyable toggle

A 32 bit machine with HIGHMEM64 enabled running DCC has an MMAPed file of
approximately 2Gb size which contains a hash format that is written
randomly by the dbclean process.  On 2.6.16 this process took a few
minutes.  With lowmem only accounting of dirty ratios, this takes about 12
hours of 100% disk IO, all random writes.

Include a toggle in /proc/sys/vm/highmem_is_dirtyable which can be set to 1 to
add the highmem back to the total available memory count.

[akpm@linux-foundation.org: Fix the CONFIG_DETECT_SOFTLOCKUP=y build]
Signed-off-by: Bron Gondwana 
Cc: Ethan Solomita 
Cc: Peter Zijlstra 
Cc: WU Fengguang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Revert "writeback: introduce writeback_control.more_io to indicate more io"

2008-01-15T05:21:29+00:00

This reverts commit 2e6883bdf49abd0e7f0d9b6297fc3be7ebb2250b, as
requested by Fengguang Wu.  It's not quite fully baked yet, and while
there are patches around to fix the problems it caused, they should get
more testing.  Says Fengguang: "I'll resend them both for -mm later on,
in a more complete patchset".

See

	http://bugzilla.kernel.org/show_bug.cgi?id=9738

for some of this discussion.

Requested-by: Fengguang Wu 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Signed-off-by: Linus Torvalds

introduce I_SYNC

2007-10-17T15:43:02+00:00

I_LOCK was used for several unrelated purposes, which caused deadlock
situations in certain filesystems as a side effect.  One of the purposes
now uses the new I_SYNC bit.

Also document the various bits and change their order from historical to
logical.

[bunk@stusta.de: make fs/inode.c:wake_up_inode() static]
Signed-off-by: Joern Engel 
Cc: Dave Kleikamp 
Cc: David Chinner 
Cc: Anton Altaparmakov 
Cc: Al Viro 
Cc: Christoph Hellwig 
Signed-off-by: Adrian Bunk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

writeback: introduce writeback_control.more_io to indicate more io

2007-10-17T15:43:02+00:00

After making dirty a 100M file, the normal behavior is to start the writeback
for all data after 30s delays.  But sometimes the following happens instead:

	- after 30s:    ~4M
	- after 5s:     ~4M
	- after 5s:     all remaining 92M

Some analyze shows that the internal io dispatch queues goes like this:

		s_io            s_more_io
		-------------------------
	1)	100M,1K         0
	2)	1K              96M
	3)	0               96M

1) initial state with a 100M file and a 1K file
2) 4M written, nr_to_write <= 0, so write more
3) 1K written, nr_to_write > 0, no more writes(BUG)

nr_to_write > 0 in (3) fools the upper layer to think that data have all been
written out.  The big dirty file is actually still sitting in s_more_io.  We
cannot simply splice s_more_io back to s_io as soon as s_io becomes empty, and
let the loop in generic_sync_sb_inodes() continue: this may starve newly
expired inodes in s_dirty.  It is also not an option to draw inodes from both
s_more_io and s_dirty, an let the loop go on: this might lead to live locks,
and might also starve other superblocks in sync time(well kupdate may still
starve some superblocks, that's another bug).

We have to return when a full scan of s_io completes.  So nr_to_write > 0 does
not necessarily mean that "all data are written".  This patch introduces a
flag writeback_control.more_io to indicate this situation.  With it the big
dirty file no longer has to wait for the next kupdate invocation 5s later.

Cc: David Chinner 
Cc: Ken Chen 
Signed-off-by: Fengguang Wu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: per device dirty threshold

2007-10-17T15:42:45+00:00

Scale writeback cache per backing device, proportional to its writeout speed.

By decoupling the BDI dirty thresholds a number of problems we currently have
will go away, namely:

 - mutual interference starvation (for any number of BDIs);
 - deadlocks with stacked BDIs (loop, FUSE and local NFS mounts).

It might be that all dirty pages are for a single BDI while other BDIs are
idling. By giving each BDI a 'fair' share of the dirty limit, each one can have
dirty pages outstanding and make progress.

A global threshold also creates a deadlock for stacked BDIs; when A writes to
B, and A generates enough dirty pages to get throttled, B will never start
writeback until the dirty pages go away. Again, by giving each BDI its own
'independent' dirty limit, this problem is avoided.

So the problem is to determine how to distribute the total dirty limit across
the BDIs fairly and efficiently. A DBI that has a large dirty limit but does
not have any dirty pages outstanding is a waste.

What is done is to keep a floating proportion between the DBIs based on
writeback completions. This way faster/more active devices get a larger share
than slower/idle devices.

[akpm@linux-foundation.org: fix warnings]
[hugh@veritas.com: Fix occasional hang when a task couldn't get out of balance_dirty_pages]
Signed-off-by: Peter Zijlstra 
Signed-off-by: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge git://git.linux-nfs.org/pub/linux/nfs-2.6

2007-10-15T17:47:35+00:00

* git://git.linux-nfs.org/pub/linux/nfs-2.6: (131 commits)
  NFSv4: Fix a typo in nfs_inode_reclaim_delegation
  NFS: Add a boot parameter to disable 64 bit inode numbers
  NFS: nfs_refresh_inode should clear cache_validity flags on success
  NFS: Fix a connectathon regression in NFSv3 and NFSv4
  NFS: Use nfs_refresh_inode() in ops that aren't expected to change the inode
  SUNRPC: Don't call xprt_release in call refresh
  SUNRPC: Don't call xprt_release() if call_allocate fails
  SUNRPC: Fix buggy UDP transmission
  [23/37] Clean up duplicate includes in
  [2.6 patch] net/sunrpc/rpcb_clnt.c: make struct rpcb_program static
  SUNRPC: Use correct type in buffer length calculations
  SUNRPC: Fix default hostname created in rpc_create()
  nfs: add server port to rpc_pipe info file
  NFS: Get rid of some obsolete macros
  NFS: Simplify filehandle revalidation
  NFS: Ensure that nfs_link() returns a hashed dentry
  NFS: Be strict about dentry revalidation when doing exclusive create
  NFS: Don't zap the readdir caches upon error
  NFS: Remove the redundant nfs_reval_fsid()
  NFSv3: Always use directory post-op attributes in nfs3_proc_lookup
  ...

Fix up trivial conflict due to sock_owned_by_user() cleanup manually in
net/sunrpc/xprtsock.c

Fix warnings with !CONFIG_BLOCK

2007-10-10T07:25:57+00:00

Hide everything in blkdev.h with CONFIG_BLOCK isn't set, and fixup
the (few) files that fail to build because they were relying on blkdev.h
pulling in extra includes for them.

Signed-off-by: Jens Axboe

VFS: Remove writeback_control->fs_private

2007-10-09T21:15:16+00:00

The only user of this field was NFS.

Signed-off-by: Trond Myklebust