linux-stable.git/fs/nfs/write.c, branch linux-3.0.y

mm: compaction: introduce sync-light migration for use by compaction

2012-08-01T19:27:18+00:00

commit a6bc32b899223a877f595ef9ddc1e89ead5072b8 upstream.

Stable note: Not tracked in Buzilla. This was part of a series that
	reduced interactivity stalls experienced when THP was enabled.
	These stalls were particularly noticable when copying data
	to a USB stick but the experiences for users varied a lot.

This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT
mode that avoids writing back pages to backing storage.  Async compaction
maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT.
For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is
used.

This avoids sync compaction stalling for an excessive length of time,
particularly when copying files to a USB stick where there might be a
large number of dirty pages backed by a filesystem that does not support
->writepages.

[aarcange@redhat.com: This patch is heavily based on Andrea's work]
[akpm@linux-foundation.org: fix fs/nfs/write.c build]
[akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build]
Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Cc: Andrea Arcangeli 
Cc: Minchan Kim 
Cc: Dave Jones 
Cc: Jan Kara 
Cc: Andy Isaacson 
Cc: Nai Xia 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Mel Gorman 
Signed-off-by: Greg Kroah-Hartman

mm: compaction: determine if dirty pages can be migrated without blocking within ->migratepage

2012-08-01T19:27:17+00:00

commit b969c4ab9f182a6e1b2a0848be349f99714947b0 upstream.

Stable note: Not tracked in Bugzilla. A fix aimed at preserving page
	aging information by reducing LRU list churning had the side-effect
	of reducing THP allocation success rates. This was part of a series
	to restore the success rates while preserving the reclaim fix.

Asynchronous compaction is used when allocating transparent hugepages to
avoid blocking for long periods of time.  Due to reports of stalling,
there was a debate on disabling synchronous compaction but this severely
impacted allocation success rates.  Part of the reason was that many dirty
pages are skipped in asynchronous compaction by the following check;

	if (PageDirty(page) && !sync &&
		mapping->a_ops->migratepage != migrate_page)
			rc = -EBUSY;

This skips over all mapping aops using buffer_migrate_page() even though
it is possible to migrate some of these pages without blocking.  This
patch updates the ->migratepage callback with a "sync" parameter.  It is
the responsibility of the callback to fail gracefully if migration would
block.

Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Cc: Andrea Arcangeli 
Cc: Minchan Kim 
Cc: Dave Jones 
Cc: Jan Kara 
Cc: Andy Isaacson 
Cc: Nai Xia 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Mel Gorman 
Signed-off-by: Greg Kroah-Hartman

nfs: don't try to migrate pages with active requests

2011-11-11T17:35:54+00:00

commit 2da956523526e440ef4f4dd174e26f5ac06fe011 upstream.

nfs_find_and_lock_request will take a reference to the nfs_page and
will then put it if the req is already locked. It's possible though
that the reference will be the last one. That put then can kick off
a whole series of reference puts:

nfs_page
   nfs_open_context
      dentry
          inode

If the inode ends up being deleted, then the VFS will call
truncate_inode_pages. That function will try to take the page lock, but
it was already locked when migrate_page was called. The code
deadlocks.

Fix this by simply refusing the migration request if PagePrivate is
already set, indicating that the page is already associated with an
active read or write request.

We've had a customer test a backported version of this patch and
the preliminary results seem good.

Cc: Andrea Arcangeli 
Reported-by: Harshula Jayasuriya 
Signed-off-by: Jeff Layton 
Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

nfs: don't redirty inode when ncommit == 0 in nfs_commit_unstable_pages

2011-11-11T17:35:50+00:00

commit 3236c3e1adc0c7ec83eaff1de2d06746b7c5bb28 upstream.

commit 420e3646 allowed the kernel to reduce the number of unnecessary
commit calls by skipping the commit when there are a large number of
outstanding pages.

However, the current test in nfs_commit_unstable_pages does not handle
the edge condition properly. When ncommit == 0, then that means that the
kernel doesn't need to do anything more for the inode. The current test
though in the WB_SYNC_NONE case will return true, and the inode will end
up being marked dirty. Once that happens the inode will never be clean
until there's a WB_SYNC_ALL flush.

Fix this by immediately returning from nfs_commit_unstable_pages when
ncommit == 0.

Mike noticed this problem initially in RHEL5 (2.6.18-based kernel) which
has a backported version of 420e3646. The inode cache there was growing
very large. The inode cache was unable to be shrunk since the inodes
were all marked dirty. Calling sync() would essentially "fix" the
problem -- the WB_SYNC_ALL flush would result in the inodes all being
marked clean.

What I'm not clear on is how big a problem this is in mainline kernels
as the writeback code there is very different. Either way, it seems
incorrect to re-mark the inode dirty in this case.

Reported-by: Mike McLean 
Signed-off-by: Jeff Layton 
Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

Revert "NFS: Ensure that writeback_single_inode() calls write_inode() when syncing"

2011-11-11T17:35:49+00:00

commit 59b7c05fffba030e5d9e72324691e2f99aa69b79 upstream.

This reverts commit b80c3cb628f0ebc241b02e38dd028969fb8026a2.

The reverted commit was rendered obsolete by a VFS fix: commit
5547e8aac6f71505d621a612de2fca0dd988b439 (writeback: Update dirty flags in
two steps). We now no longer need to worry about writeback_single_inode()
missing our marking the inode for COMMIT in 'do_writepages()' call.

Reverting this patch, fixes a performance regression in which the inode
would continuously get queued to the dirty list, causing the writeback
code to unnecessarily try to send a COMMIT.

Signed-off-by: Trond Myklebust 
Tested-by: Simon Kirby 
Signed-off-by: Greg Kroah-Hartman

pnfs: write: Set mds_offset in the generic layer - it is needed by all LDs

2011-06-28T18:12:11+00:00

In current pnfs tree, all the layouts set mds_offset in their
.write_pagelist member.
mds_offset is only used by generic layer and should be handled by it.

This patch is for upstream. It is needed in this -rc series to fix a
bug in objects layout_commit.

I'll send patches for objects and blocks to be
squashed into current pnfs tree.

TODO: It looks like the read path needs the same patch.

Signed-off-by: Boaz Harrosh 
Signed-off-by: Trond Myklebust

NFSv4.1: unify pnfs_pageio_init functions

2011-05-29T17:56:43+00:00

Use common code for pnfs_pageio_init_{read,write} and use
a common generic pg_test function.

Note that this function always assumes the the layout driver's
pg_test method is implemented.

[Fix BUG]
Signed-off-by: Boaz Harrosh 
Signed-off-by: Benny Halevy

pnfs: Use byte-range for layoutget

2011-05-29T17:52:32+00:00

Add offset and count parameters to pnfs_update_layout and use them to get
the layout in the pageio path.

Order cache layout segments in the following order:
* offset (ascending)
* length (descending)
* iomode (RW before READ)

Test byte range against the layout segment in use in pnfs_{read,write}_pg_test
so not to coalesce pages not using the same layout segment.

[fix lseg ordering]
[clean up pnfs_find_lseg lseg arg]
[remove unnecessary FIXME]
[fix ordering in pnfs_insert_layout]
[clean up pnfs_insert_layout]
Signed-off-by: Benny Halevy

NFSv4.1: Ensure that layoutget uses the correct gfp modes

2011-05-12T02:52:13+00:00

Currently, writebacks may end up recursing back into the filesystem due to
GFP_KERNEL direct reclaims in the pnfs subsystem.

Signed-off-by: Trond Myklebust

NFS: Get rid of pointless test in nfs_commit_done

2011-04-12T23:34:23+00:00

Signed-off-by: Trond Myklebust