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authorNick Piggin <npiggin@suse.de>2009-01-06 14:39:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 15:58:59 -0800
commitbd19e012f6fd3b7309689165ea865cbb7bb88c1e (patch)
tree66ca4f5bfc683d2935e7fc5cab2f57a7682ad65a
parent31a12666d8f0c22235297e1c1575f82061480029 (diff)
mm: write_cache_pages early loop termination
We'd like to break out of the loop early in many situations, however the existing code has been setting mapping->writeback_index past the final page in the pagevec lookup for cyclic writeback. This is a problem if we don't process all pages up to the final page. Currently the code mostly keeps writeback_index reasonable and hacked around this by not breaking out of the loop or writing pages outside the range in these cases. Keep track of a real "done index" that enables us to terminate the loop in a much more flexible manner. Needed by the subsequent patch to preserve writepage errors, and then further patches to break out of the loop early for other reasons. However there are no functional changes with this patch alone. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page-writeback.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index eb277bdd4c5..01b9cb8ccf6 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -871,6 +871,7 @@ int write_cache_pages(struct address_space *mapping,
pgoff_t uninitialized_var(writeback_index);
pgoff_t index;
pgoff_t end; /* Inclusive */
+ pgoff_t done_index;
int cycled;
int range_whole = 0;
long nr_to_write = wbc->nr_to_write;
@@ -897,6 +898,7 @@ int write_cache_pages(struct address_space *mapping,
cycled = 1; /* ignore range_cyclic tests */
}
retry:
+ done_index = index;
while (!done && (index <= end) &&
(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
PAGECACHE_TAG_DIRTY,
@@ -906,6 +908,8 @@ retry:
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
+ done_index = page->index + 1;
+
/*
* At this point we hold neither mapping->tree_lock nor
* lock on the page itself: the page may be truncated or
@@ -968,7 +972,7 @@ retry:
}
if (!wbc->no_nrwrite_index_update) {
if (wbc->range_cyclic || (range_whole && nr_to_write > 0))
- mapping->writeback_index = index;
+ mapping->writeback_index = done_index;
wbc->nr_to_write = nr_to_write;
}