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author | OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> | 2006-06-23 09:03:26 (GMT) |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-23 14:42:49 (GMT) |
commit | 111ebb6e6f7bd7de6d722c5848e95621f43700d9 (patch) | |
tree | bb00b13001db9be201e9b6d31468a79f4d1240bf /include/linux/writeback.h | |
parent | 4c91c3648c620003cb7b21b8858f36cd6132e168 (diff) | |
download | linux-fsl-qoriq-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 'include/linux/writeback.h')
-rw-r--r-- | include/linux/writeback.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 56f92fc..9e38b56 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -50,14 +50,15 @@ struct writeback_control { * a hint that the filesystem need only write out the pages inside that * byterange. The byte at `end' is included in the writeout request. */ - loff_t start; - loff_t end; + loff_t range_start; + loff_t range_end; unsigned nonblocking:1; /* Don't get stuck on request queues */ unsigned encountered_congestion:1; /* An output: a queue is full */ unsigned for_kupdate:1; /* A kupdate writeback */ unsigned for_reclaim:1; /* Invoked from the page allocator */ unsigned for_writepages:1; /* This is a writepages() call */ + unsigned range_cyclic:1; /* range_start is cyclic */ }; /* |