linux-toradex.git/fs/fs-writeback.c, branch v2.6.18

[PATCH] zoned vm counters: conversion of nr_unstable to per zone counter

2006-06-30T18:25:36+00:00

Conversion of nr_unstable to a per zone counter

We need to do some special modifications to the nfs code since there are
multiple cases of disposition and we need to have a page ref for proper
accounting.

This converts the last critical page state of the VM and therefore we need to
remove several functions that were depending on GET_PAGE_STATE_LAST in order
to make the kernel compile again.  We are only left with event type counters
in page state.

[akpm@osdl.org: bugfixes]
Signed-off-by: Christoph Lameter 
Cc: Trond Myklebust 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] zoned vm counters: conversion of nr_dirty to per zone counter

2006-06-30T18:25:35+00:00

This makes nr_dirty a per zone counter.  Looping over all processors is
avoided during writeback state determination.

The counter aggregation for nr_dirty had to be undone in the NFS layer since
we summed up the page counts from multiple zones.  Someone more familiar with
NFS should probably review what I have done.

[akpm@osdl.org: bugfix]
Signed-off-by: Christoph Lameter 
Cc: Trond Myklebust 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Kill PF_SYNCWRITE flag

2006-06-23T15:10:39+00:00

A process flag to indicate whether we are doing sync io is incredibly
ugly. It also causes performance problems when one does a lot of async
io and then proceeds to sync it. Part of the io will go out as async,
and the other part as sync. This causes a disconnect between the
previously submitted io and the synced io. For io schedulers such as CFQ,
this will cause us lost merges and suboptimal behaviour in scheduling.

Remove PF_SYNCWRITE completely from the fsync/msync paths, and let
the O_DIRECT path just directly indicate that the writes are sync
by using WRITE_SYNC instead.

Signed-off-by: Jens Axboe

[PATCH] writeback: fix range handling

2006-06-23T14:42:49+00:00

When a writeback_control's `start' and `end' fields are used to
indicate a one-byte-range starting at file offset zero, the required
values of .start=0,.end=0 mean that the ->writepages() implementation
has no way of telling that it is being asked to perform a range
request.  Because we're currently overloading (start == 0 && end == 0)
to mean "this is not a write-a-range request".

To make all this sane, the patch changes range of writeback_control.

So caller does: If it is calling ->writepages() to write pages, it
sets range (range_start/end or range_cyclic) always.

And if range_cyclic is true, ->writepages() thinks the range is
cyclic, otherwise it just uses range_start and range_end.

This patch does,

    - Add LLONG_MAX, LLONG_MIN, ULLONG_MAX to include/linux/kernel.h
      -1 is usually ok for range_end (type is long long). But, if someone did,

		range_end += val;		range_end is "val - 1"
		u64val = range_end >> bits;	u64val is "~(0ULL)"

      or something, they are wrong. So, this adds LLONG_MAX to avoid nasty
      things, and uses LLONG_MAX for range_end.

    - All callers of ->writepages() sets range_start/end or range_cyclic.

    - Fix updates of ->writeback_index. It seems already bit strange.
      If it starts at 0 and ended by check of nr_to_write, this last
      index may reduce chance to scan end of file.  So, this updates
      ->writeback_index only if range_cyclic is true or whole-file is
      scanned.

Signed-off-by: OGAWA Hirofumi 
Cc: Nathan Scott 
Cc: Anton Altaparmakov 
Cc: Steven French 
Cc: "Vladimir V. Saveliev" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Move cond_resched() after iput() in sync_sb_inodes()

2006-03-25T16:22:56+00:00

In here, I think the following order is more cache-friendly.

Signed-off-by: OGAWA Hirofumi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] kernel-docs: fix kernel-doc format problems

2005-11-07T15:53:55+00:00

Convert to proper kernel-doc format.

Some have extra blank lines (not allowed immed.  after the function name)
or need blank lines (after all parameters).  Function summary must be only
one line.

Colon (":") in a function description does weird things (causes kernel-doc
to think that it's a new section head sadly).

Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] write_inode_now(): write inode if not BDI_CAP_NO_WRITEBACK

2005-11-07T15:53:35+00:00

If the backing_dev_info doesn't have BDI_CAP_NO_WRITEBACK we're not supposed
to write back an inode's pages.  But in this situation write_inode_now()
refuses to write the inode itself as well.  Fix.

Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] fix __writeback_single_inode WARN_ON

2005-10-31T22:22:04+00:00

When the inode count is zero in inode writeback, the

	WARN_ON(!(inode->i_state & I_WILL_FREE));

is broken, and needs to test for either I_WILL_FREE|I_FREEING.

When the inode is in I_FREEING state, it's already out of the visibility
of the vm so it can't be freed so it doesn't require the __iget and the
generic_delete_inode path can call the sync internally to the lowlevel
fs callback during the last iput. So the inode being in I_FREEING is
also a valid condition for calling the sync with i_count == 0.

The specific stack trace is this:

  0xc00000007b8fb6e0  0xc00000000010118c  .__writeback_single_inode +0x5c
  0xc00000007b8fb6e0  0xc0000000001014dc (lr) .sync_inode +0x3c
  0xc00000007b8fb790  0xc0000000001014dc  .sync_inode +0x3c
  0xc00000007b8fb820  0xc0000000001a5020  .ext2_sync_inode +0x64
  0xc00000007b8fb8f0  0xc0000000001a65b4  .ext2_truncate +0x3f8
  0xc00000007b8fba40  0xc0000000001a6940  .ext2_delete_inode +0xdc
  0xc00000007b8fbac0  0xc0000000000f7a5c  .generic_delete_inode +0x124
  0xc00000007b8fbb50  0xc0000000000f5fe0  .iput +0xb8
  0xc00000007b8fbbe0  0xc0000000000e9fd4  .sys_unlink +0x2a8
  0xc00000007b8fbd10  0xc00000000001048c  .ret_from_syscall_1 +0x0

Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] fix nr_unused accounting, and avoid recursing in iput with I_WILL_FREE set

2005-10-31T01:37:26+00:00

 			list_move(&inode->i_list, &inode_in_use);
 		} else {
 			list_move(&inode->i_list, &inode_unused);
+			inodes_stat.nr_unused++;
 		}
 	}
 	wake_up_inode(inode);

Are you sure the above diff is correct? It was added somewhere between
2.6.5 and 2.6.8. I think it's wrong.

The only way I can imagine the i_count to be zero in the above path, is
that I_WILL_FREE is set.  And if I_WILL_FREE is set, then we must not
increase nr_unused.  So I believe the above change is buggy and it will
definitely overstate the number of unused inodes and it should be backed
out.

Note that __writeback_single_inode before calling __sync_single_inode, can
drop the spinlock and we can have both the dirty and locked bitflags clear
here:

		spin_unlock(&inode_lock);
		__wait_on_inode(inode);
		iput(inode);
XXXXXXX
		spin_lock(&inode_lock);
	}
	use inode again here

a construct like the above makes zero sense from a reference counting
standpoint.

Either we don't ever use the inode again after the iput, or the
inode_lock should be taken _before_ executing the iput (i.e. a __iput
would be required). Taking the inode_lock after iput means the iget was
useless if we keep using the inode after the iput.

So the only chance the 2.6 was safe to call __writeback_single_inode
with the i_count == 0, is that I_WILL_FREE is set (I_WILL_FREE will
prevent the VM to free the inode in XXXXX).

Potentially calling the above iput with I_WILL_FREE was also wrong
because it would recurse in iput_final (the second mainline bug).

The below (untested) patch fixes the nr_unused accounting, avoids recursing
in iput when I_WILL_FREE is set and makes sure (with the BUG_ON) that we
don't corrupt memory and that all holders that don't set I_WILL_FREE, keeps
a reference on the inode!

Signed-off-by: Andrea Arcangeli 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] O(1) sb list traversing on syncs

2005-06-23T16:45:27+00:00

This patch removes O(n^2) super block loops in sync_inodes(),
sync_filesystems() etc.  in favour of using __put_super_and_need_restart()
which I introduced earlier.  We faced a noticably long freezes on sb
syncing when there are thousands of super blocks in the system.

Signed-Off-By: Kirill Korotaev 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds