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authorOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>2006-06-23 05:03:26 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-23 10:42:49 -0400
commit111ebb6e6f7bd7de6d722c5848e95621f43700d9 (patch)
treebb00b13001db9be201e9b6d31468a79f4d1240bf /include/linux/writeback.h
parent4c91c3648c620003cb7b21b8858f36cd6132e168 (diff)
[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 'include/linux/writeback.h')
-rw-r--r--include/linux/writeback.h5
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 56f92fcbe94a..9e38b566d0e7 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -50,14 +50,15 @@ struct writeback_control {
50 * a hint that the filesystem need only write out the pages inside that 50 * a hint that the filesystem need only write out the pages inside that
51 * byterange. The byte at `end' is included in the writeout request. 51 * byterange. The byte at `end' is included in the writeout request.
52 */ 52 */
53 loff_t start; 53 loff_t range_start;
54 loff_t end; 54 loff_t range_end;
55 55
56 unsigned nonblocking:1; /* Don't get stuck on request queues */ 56 unsigned nonblocking:1; /* Don't get stuck on request queues */
57 unsigned encountered_congestion:1; /* An output: a queue is full */ 57 unsigned encountered_congestion:1; /* An output: a queue is full */
58 unsigned for_kupdate:1; /* A kupdate writeback */ 58 unsigned for_kupdate:1; /* A kupdate writeback */
59 unsigned for_reclaim:1; /* Invoked from the page allocator */ 59 unsigned for_reclaim:1; /* Invoked from the page allocator */
60 unsigned for_writepages:1; /* This is a writepages() call */ 60 unsigned for_writepages:1; /* This is a writepages() call */
61 unsigned range_cyclic:1; /* range_start is cyclic */
61}; 62};
62 63
63/* 64/*