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authorOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>2006-06-23 13:03:26 +0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-23 18:42:49 +0400
commit111ebb6e6f7bd7de6d722c5848e95621f43700d9 (patch)
treebb00b13001db9be201e9b6d31468a79f4d1240bf /mm/page-writeback.c
parent4c91c3648c620003cb7b21b8858f36cd6132e168 (diff)
downloadlinux-111ebb6e6f7bd7de6d722c5848e95621f43700d9.tar.xz
[PATCH] writeback: fix range handling
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 <hirofumi@mail.parknet.co.jp> Cc: Nathan Scott <nathans@sgi.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Steven French <sfrench@us.ibm.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/page-writeback.c')
-rw-r--r--mm/page-writeback.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 75d7f48b79bb..8ccf6f1b1473 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -204,6 +204,7 @@ static void balance_dirty_pages(struct address_space *mapping)
.sync_mode = WB_SYNC_NONE,
.older_than_this = NULL,
.nr_to_write = write_chunk,
+ .range_cyclic = 1,
};
get_dirty_limits(&wbs, &background_thresh,
@@ -331,6 +332,7 @@ static void background_writeout(unsigned long _min_pages)
.older_than_this = NULL,
.nr_to_write = 0,
.nonblocking = 1,
+ .range_cyclic = 1,
};
for ( ; ; ) {
@@ -407,6 +409,7 @@ static void wb_kupdate(unsigned long arg)
.nr_to_write = 0,
.nonblocking = 1,
.for_kupdate = 1,
+ .range_cyclic = 1,
};
sync_supers();