This is a note to let you know that we have just queued up the patch titled
Subject: vfs: Add no_nrwrite_index_update writeback control flag
to the 2.6.27-stable tree. Its filename is
vfs-add-no_nrwrite_index_update-writeback-control-flag.patch
A git repo of this tree can be found at
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
>From tytso@xxxxxxx Mon Apr 19 10:23:14 2010
From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Date: Mon, 15 Mar 2010 20:26:03 -0400
Subject: vfs: Add no_nrwrite_index_update writeback control flag
To: stable@xxxxxxxxxx
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, Ext4 Developers List <linux-ext4@xxxxxxxxxxxxxxx>, "Theodore Ts'o" <tytso@xxxxxxx>, "Jayson R. King" <dev@xxxxxxxxxxxxxx>, "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Message-ID: <1268699165-17461-10-git-send-email-tytso@xxxxxxx>
From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
commit 17bc6c30cf6bfffd816bdc53682dd46fc34a2cf4 upstream.
If no_nrwrite_index_update is set we don't update nr_to_write and
address space writeback_index in write_cache_pages. This change
enables a file system to skip these updates in write_cache_pages and do
them in the writepages() callback. This patch will be followed by an
ext4 patch that make use of these new flags.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
CC: linux-fsdevel@xxxxxxxxxxxxxxx
[dev@xxxxxxxxxxxxxx: Modified the patch to account for subsequent changes in mainline being cherry-picked earlier for 2.6.27.y.]
Signed-off-by: Jayson R. King <dev@xxxxxxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
include/linux/writeback.h | 9 +++++++++
mm/page-writeback.c | 14 +++++++++-----
2 files changed, 18 insertions(+), 5 deletions(-)
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -62,6 +62,15 @@ struct writeback_control {
unsigned for_writepages:1; /* This is a writepages() call */
unsigned range_cyclic:1; /* range_start is cyclic */
unsigned more_io:1; /* more io to be dispatched */
+ /*
+ * write_cache_pages() won't update wbc->nr_to_write and
+ * mapping->writeback_index if no_nrwrite_index_update
+ * is set. write_cache_pages() may write more than we
+ * requested and we want to make sure nr_to_write and
+ * writeback_index are updated in a consistent manner
+ * so we use a single control to update them
+ */
+ unsigned no_nrwrite_index_update:1;
};
/*
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -878,6 +878,7 @@ int write_cache_pages(struct address_spa
pgoff_t done_index;
int cycled;
int range_whole = 0;
+ long nr_to_write = wbc->nr_to_write;
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
@@ -985,9 +986,9 @@ continue_unlock:
}
}
- if (wbc->nr_to_write > 0) {
- wbc->nr_to_write--;
- if (wbc->nr_to_write == 0 &&
+ if (nr_to_write > 0) {
+ nr_to_write--;
+ if (nr_to_write == 0 &&
wbc->sync_mode == WB_SYNC_NONE) {
/*
* We stop writing back only if we are
@@ -1024,8 +1025,11 @@ continue_unlock:
end = writeback_index - 1;
goto retry;
}
- if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
- mapping->writeback_index = done_index;
+ if (!wbc->no_nrwrite_index_update) {
+ if (wbc->range_cyclic || (range_whole && nr_to_write > 0))
+ mapping->writeback_index = done_index;
+ wbc->nr_to_write = nr_to_write;
+ }
return ret;
}
Patches currently in stable-queue which might be from aneesh.kumar@xxxxxxxxxxxxxxxxxx are
queue-2.6.27/ext4-fix-file-fragmentation-during-large-file-write.patch
queue-2.6.27/ext4-retry-block-allocation-if-we-have-free-blocks-left.patch
queue-2.6.27/vfs-add-no_nrwrite_index_update-writeback-control-flag.patch
queue-2.6.27/ext4-retry-block-reservation.patch
queue-2.6.27/ext4-invalidate-pages-if-delalloc-block-allocation-fails.patch
queue-2.6.27/ext4-use-tag-dirty-lookup-during-mpage_da_submit_io.patch
queue-2.6.27/vfs-remove-the-range_cont-writeback-mode.patch
queue-2.6.27/ext4-make-sure-all-the-block-allocation-paths-reserve-blocks.patch
queue-2.6.27/ext4-implement-range_cyclic-in-ext4_da_writepages-instead-of-write_cache_pages.patch
queue-2.6.27/ext4-add-percpu-dirty-block-accounting.patch
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