The patch titled
fix blk_direct_IO bio preparation
has been added to the -mm tree. Its filename is
fix-blk_direct_io-bio-preparation.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: fix blk_direct_IO bio preparation
From: "Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx>
For large size DIO that needs multiple bio, one full page worth of data was
lost at the boundary of bio's maximum sector or segment limits. After a
bio is full and got submitted. The outer while (nbytes) { ... } loop will
allocate a new bio and just march on to index into next page. It just
forgets about the page that bio_add_page() rejected when previous bio is
full. Fix it by put the rejected page back to pvec so we pick it up again
for the next bio.
Signed-off-by: Ken Chen <kenneth.w.chen@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/block_dev.c | 8 ++++++++
1 files changed, 8 insertions(+)
diff -puN fs/block_dev.c~fix-blk_direct_io-bio-preparation fs/block_dev.c
--- a/fs/block_dev.c~fix-blk_direct_io-bio-preparation
+++ a/fs/block_dev.c
@@ -190,6 +190,12 @@ static struct page *blk_get_page(unsigne
return pvec->page[pvec->idx++];
}
+/* return a pge back to pvec array */
+static void blk_unget_page(struct page *page, struct pvec *pvec)
+{
+ pvec->page[--pvec->idx] = page;
+}
+
static ssize_t
blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
loff_t pos, unsigned long nr_segs)
@@ -278,6 +284,8 @@ same_bio:
count = min(count, nbytes);
goto same_bio;
}
+ } else {
+ blk_unget_page(page, &pvec);
}
/* bio is ready, submit it */
_
Patches currently in -mm which might be from kenneth.w.chen@xxxxxxxxx are
blockdev-direct_io-fix-signedness-bug.patch
submitchecklist-update.patch
fix-blk_direct_io-bio-preparation.patch
ia64-alignment-bug-in-ldscript.patch
aio-fix-buggy-put_ioctx-call-in-aio_complete-v2.patch
mm-only-sched-add-a-few-scheduler-event-counters.patch
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