* [BUGFIX take 2] [PATCH] write-back: fix nr_to_write counter
@ 2009-02-03 10:08 Artem Bityutskiy
2009-02-03 13:41 ` Dave Kleikamp
0 siblings, 1 reply; 4+ messages in thread
From: Artem Bityutskiy @ 2009-02-03 10:08 UTC (permalink / raw)
To: torvalds
Cc: Andrew Morton, Nick Piggin, Linux Kernel Mailing List,
linux-fsdevel
From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Date: Mon, 2 Feb 2009 18:33:49 +0200
Subject: [PATCH] write-back: fix nr_to_write counter
Commit 05fe478dd04e02fa230c305ab9b5616669821dd3 introduced some
@wbc->nr_to_write breakage. Here is the change from the commit:
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -963,8 +963,10 @@ retry:
}
}
- if (--nr_to_write <= 0)
- done = 1;
+ if (wbc->sync_mode == WB_SYNC_NONE) {
+ if (--wbc->nr_to_write <= 0)
+ done = 1;
+ }
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
done = 1
}
It makes the following changes:
1. Decrement wbc->nr_to_write instead of nr_to_write
2. Decrement wbc->nr_to_write _only_ if wbc->sync_mode == WB_SYNC_NONE
3. If synced nr_to_write pages, stop only if if wbc->sync_mode ==
WB_SYNC_NONE, otherwise keep going.
However, according to the commit message, the intention was to
only make change 3. Change 1 is a bug. Change 2 does not seem to be
necessary, and it breaks UBIFS expectations, so if needed, it
should be done separately later. And change 2 does not seem to
be documented in the commit message.
This patch des the following:
1. Undo changes 1 and 2
2. Add a comment explaining change 3 (it very useful to have comments in
_code_, not only in the commit).
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
mm/page-writeback.c | 21 +++++++++++++++------
1 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b493db7..13a2b8e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1051,13 +1051,22 @@ continue_unlock:
}
}
- if (wbc->sync_mode == WB_SYNC_NONE) {
- wbc->nr_to_write--;
- if (wbc->nr_to_write <= 0) {
- done = 1;
- break;
- }
+ if (nr_to_write > 0)
+ nr_to_write--;
+ else if (wbc->sync_mode == WB_SYNC_NONE) {
+ /*
+ * We stop writing back only if we are not
+ * doing integrity sync. In case of integrity
+ * sync we have to keep going because someone
+ * may be concurrently dirtying pages, and we
+ * might have synced a lot of newly appeared
+ * dirty pages, bud have not synced all of the
+ * old dirty pages.
+ */
+ done = 1;
+ break;
}
+
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
done = 1;
--
1.6.0.6
--
Best regards,
Artem Bityutskiy (Битюцкий Артём)
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^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [BUGFIX take 2] [PATCH] write-back: fix nr_to_write counter
2009-02-03 10:08 [BUGFIX take 2] [PATCH] write-back: fix nr_to_write counter Artem Bityutskiy
@ 2009-02-03 13:41 ` Dave Kleikamp
2009-02-03 14:45 ` [BUGFIX take 3] " Artem Bityutskiy
0 siblings, 1 reply; 4+ messages in thread
From: Dave Kleikamp @ 2009-02-03 13:41 UTC (permalink / raw)
To: dedekind
Cc: torvalds, Andrew Morton, Nick Piggin, Linux Kernel Mailing List,
linux-fsdevel
On Tue, 2009-02-03 at 12:08 +0200, Artem Bityutskiy wrote:
> From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
> Date: Mon, 2 Feb 2009 18:33:49 +0200
> Subject: [PATCH] write-back: fix nr_to_write counter
>
> Commit 05fe478dd04e02fa230c305ab9b5616669821dd3 introduced some
> @wbc->nr_to_write breakage. Here is the change from the commit:
>
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -963,8 +963,10 @@ retry:
> }
> }
>
> - if (--nr_to_write <= 0)
> - done = 1;
> + if (wbc->sync_mode == WB_SYNC_NONE) {
> + if (--wbc->nr_to_write <= 0)
> + done = 1;
> + }
> if (wbc->nonblocking && bdi_write_congested(bdi)) {
> wbc->encountered_congestion = 1;
> done = 1
> }
Actually quoting a patch in the description in this manner will make the
patch fail to apply (or fail to apply correctly). If you must quote the
patch, you should probably prepend ">" or something.
> It makes the following changes:
> 1. Decrement wbc->nr_to_write instead of nr_to_write
> 2. Decrement wbc->nr_to_write _only_ if wbc->sync_mode == WB_SYNC_NONE
> 3. If synced nr_to_write pages, stop only if if wbc->sync_mode ==
> WB_SYNC_NONE, otherwise keep going.
>
> However, according to the commit message, the intention was to
> only make change 3. Change 1 is a bug. Change 2 does not seem to be
> necessary, and it breaks UBIFS expectations, so if needed, it
> should be done separately later. And change 2 does not seem to
> be documented in the commit message.
>
> This patch des the following:
> 1. Undo changes 1 and 2
> 2. Add a comment explaining change 3 (it very useful to have comments in
> _code_, not only in the commit).
>
> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
> Acked-by: Nick Piggin <npiggin@suse.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> mm/page-writeback.c | 21 +++++++++++++++------
> 1 files changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index b493db7..13a2b8e 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -1051,13 +1051,22 @@ continue_unlock:
> }
> }
>
> - if (wbc->sync_mode == WB_SYNC_NONE) {
> - wbc->nr_to_write--;
> - if (wbc->nr_to_write <= 0) {
> - done = 1;
> - break;
> - }
> + if (nr_to_write > 0)
> + nr_to_write--;
> + else if (wbc->sync_mode == WB_SYNC_NONE) {
> + /*
> + * We stop writing back only if we are not
> + * doing integrity sync. In case of integrity
> + * sync we have to keep going because someone
> + * may be concurrently dirtying pages, and we
> + * might have synced a lot of newly appeared
> + * dirty pages, bud have not synced all of the
> + * old dirty pages.
> + */
> + done = 1;
> + break;
> }
> +
> if (wbc->nonblocking && bdi_write_congested(bdi)) {
> wbc->encountered_congestion = 1;
> done = 1;
> --
> 1.6.0.6
>
>
--
David Kleikamp
IBM Linux Technology Center
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [BUGFIX take 3] [PATCH] write-back: fix nr_to_write counter
2009-02-03 13:41 ` Dave Kleikamp
@ 2009-02-03 14:45 ` Artem Bityutskiy
[not found] ` <49885ABD.2010600@hp.com>
0 siblings, 1 reply; 4+ messages in thread
From: Artem Bityutskiy @ 2009-02-03 14:45 UTC (permalink / raw)
To: torvalds
Cc: Andrew Morton, Nick Piggin, Linux Kernel Mailing List,
linux-fsdevel, Dave Kleikamp
[Take into account Dave Kleikamp's suggestion and fix commit message]
From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Date: Mon, 2 Feb 2009 18:33:49 +0200
Subject: [PATCH] write-back: fix nr_to_write counter
Commit 05fe478dd04e02fa230c305ab9b5616669821dd3 introduced some
@wbc->nr_to_write breakage. Here is the change from the commit:
>--- a/mm/page-writeback.c
>+++ b/mm/page-writeback.c
>@@ -963,8 +963,10 @@ retry:
> }
> }
>
> if (--nr_to_write <= 0)
> done = 1;
> if (wbc->sync_mode == WB_SYNC_NONE) {
> if (--wbc->nr_to_write <= 0)
> done = 1;
> }
> if (wbc->nonblocking && bdi_write_congested(bdi)) {
> wbc->encountered_congestion = 1;
> done = 1
> }
It makes the following changes:
1. Decrement wbc->nr_to_write instead of nr_to_write
2. Decrement wbc->nr_to_write _only_ if wbc->sync_mode == WB_SYNC_NONE
3. If synced nr_to_write pages, stop only if if wbc->sync_mode ==
WB_SYNC_NONE, otherwise keep going.
However, according to the commit message, the intention was to
only make change 3. Change 1 is a bug. Change 2 does not seem to be
necessary, and it breaks UBIFS expectations, so if needed, it
should be done separately later. And change 2 does not seem to
be documented in the commit message.
This patch does the following:
1. Undo changes 1 and 2
2. Add a comment explaining change 3 (it very useful to have comments in
_code_, not only in the commit).
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
mm/page-writeback.c | 21 +++++++++++++++------
1 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b493db7..13a2b8e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1051,13 +1051,22 @@ continue_unlock:
}
}
- if (wbc->sync_mode == WB_SYNC_NONE) {
- wbc->nr_to_write--;
- if (wbc->nr_to_write <= 0) {
- done = 1;
- break;
- }
+ if (nr_to_write > 0)
+ nr_to_write--;
+ else if (wbc->sync_mode == WB_SYNC_NONE) {
+ /*
+ * We stop writing back only if we are not
+ * doing integrity sync. In case of integrity
+ * sync we have to keep going because someone
+ * may be concurrently dirtying pages, and we
+ * might have synced a lot of newly appeared
+ * dirty pages, bud have not synced all of the
+ * old dirty pages.
+ */
+ done = 1;
+ break;
}
+
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
done = 1;
--
1.6.0.6
--
Best regards,
Artem Bityutskiy (Битюцкий Артём)
--
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the body of a message to majordomo@vger.kernel.org
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^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2009-02-03 15:44 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2009-02-03 10:08 [BUGFIX take 2] [PATCH] write-back: fix nr_to_write counter Artem Bityutskiy
2009-02-03 13:41 ` Dave Kleikamp
2009-02-03 14:45 ` [BUGFIX take 3] " Artem Bityutskiy
[not found] ` <49885ABD.2010600@hp.com>
2009-02-03 15:44 ` [BUGFIX take 4] " Artem Bityutskiy
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