linux.git, branch v2.6.28.2

Linux 2.6.28.2

2009-01-25T00:42:07+00:00

fs: sys_sync fix

2009-01-25T00:41:52+00:00

commit 856bf4d717feb8c55d4e2f817b71ebb70cfbc67b upstream.

s_syncing livelock avoidance was breaking data integrity guarantee of
sys_sync, by allowing sys_sync to skip writing or waiting for superblocks
if there is a concurrent sys_sync happening.

This livelock avoidance is much less important now that we don't have the
get_super_to_sync() call after every sb that we sync.  This was replaced
by __put_super_and_need_restart.

Signed-off-by: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fs: sync_sb_inodes fix

2009-01-25T00:41:52+00:00

commit 38f21977663126fef53f5585e7f1653d8ebe55c4 upstream.

Fix data integrity semantics required by sys_sync, by iterating over all
inodes and waiting for any writeback pages after the initial writeout.
Comments explain the exact problem.

Signed-off-by: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fs: remove WB_SYNC_HOLD

2009-01-25T00:41:51+00:00

commit 4f5a99d64c17470a784a6c68064207d82e3e74a5 upstream.

Remove WB_SYNC_HOLD.  The primary motiviation is the design of my
anti-starvation code for fsync.  It requires taking an inode lock over the
sync operation, so we could run into lock ordering problems with multiple
inodes.  It is possible to take a single global lock to solve the ordering
problem, but then that would prevent a future nice implementation of "sync
multiple inodes" based on lock order via inode address.

Seems like a backward step to remove this, but actually it is busted
anyway: we can't use the inode lists for data integrity wait: an inode can
be taken off the dirty lists but still be under writeback.  In order to
satisfy data integrity semantics, we should wait for it to finish
writeback, but if we only search the dirty lists, we'll miss it.

It would be possible to have a "writeback" list, for sys_sync, I suppose.
But why complicate things by prematurely optimise?  For unmounting, we
could avoid the "livelock avoidance" code, which would be easier, but
again premature IMO.

Fixing the existing data integrity problem will come next.

Signed-off-by: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: direct IO starvation improvement

2009-01-25T00:41:49+00:00

commit 48b47c561e41525061b5bc0cfd67d6367fd11dc4 upstream.

Direct IO can invalidate and sync a lot of pagecache pages in the mapping.
 A 4K direct IO will actually try to sync and/or invalidate the pagecache
of the entire file, for example (which might be many GB or TB large).

Improve this by doing range syncs.  Also, memory no longer has to be
unmapped to catch the dirty bits for syncing, as dirty bits would remain
coherent due to dirty mmap accounting.

This fixes the immediate DM deadlocks when doing direct IO reads to block
device with a mounted filesystem, if only by papering over the problem
somewhat rather than addressing the fsync starvation cases.

Signed-off-by: Nick Piggin 
Reviewed-by: Jeff Moyer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: do_sync_mapping_range integrity fix

2009-01-25T00:41:48+00:00

commit ee53a891f47444c53318b98dac947ede963db400 upstream.

Chris Mason notices do_sync_mapping_range didn't actually ask for data
integrity writeout.  Unfortunately, it is advertised as being usable for
data integrity operations.

This is a data integrity bug.

Signed-off-by: Nick Piggin 
Cc: Chris Mason 
Cc: Dave Chinner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: write_cache_pages more terminate quickly

2009-01-25T00:41:48+00:00

commit 82fd1a9a8ced9607312b54859572bcc6211e8919 upstream.

Now that we have the early-termination logic in place, it makes sense to
bail out early in all other cases where done is set to 1.

Signed-off-by: Nick Piggin 
Cc: Chris Mason 
Cc: Dave Chinner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: write_cache_pages terminate quickly

2009-01-25T00:41:48+00:00

commit d5482cdf8a0aacb1e6468a97d5544f5829c8d8c4 upstream.

Terminate the write_cache_pages loop upon encountering the first page past
end, without locking the page.  Pages cannot have their index change when
we have a reference on them (truncate, eg truncate_inode_pages_range
performs the same check without the page lock).

Signed-off-by: Nick Piggin 
Cc: Chris Mason 
Cc: Dave Chinner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: write_cache_pages optimise page cleaning

2009-01-25T00:41:47+00:00

commit 515f4a037fb9ab736f8bad733fcd2ffd350cf265 upstream.

In write_cache_pages, if we get stuck behind another process that is
cleaning pages, we will be forced to wait for them to finish, then perform
our own writeout (if it was redirtied during the long wait), then wait for
that.

If a page under writeout is still clean, we can skip waiting for it (if
we're part of a data integrity sync, we'll be waiting for all writeout
pages afterwards, so we'll still be waiting for the other guy's write
that's cleaned the page).

Signed-off-by: Nick Piggin 
Cc: Chris Mason 
Cc: Dave Chinner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: write_cache_pages cleanups

2009-01-25T00:41:47+00:00

commit 5a3d5c9813db56a75934eb1015367fda23a8b0b4 upstream.

Get rid of some complex expressions from flow control statements, add a
comment, remove some duplicate code.

Signed-off-by: Nick Piggin 
Cc: Chris Mason 
Cc: Dave Chinner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman