Messages in this thread Patch in this message | | | From | "Chen, Kenneth W" <> | Subject | RE: [patch] optimize o_direct on block device - v3 | Date | Thu, 11 Jan 2007 13:51:04 -0800 |
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Randy Dunlap wrote on Thursday, January 11, 2007 1:45 PM > > +/* return a pge back to pvec array */ > > is pge just a typo or some other tla that i don't know? > (not portland general electric or pacific gas & electric)
Typo with fat fingers. Thanks for catching it. Full patch with typo fixed.
[patch] fix blk_direct_IO bio preparation.
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 forget 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@intel.com>
diff -Nurp linux-2.6.20-rc4/fs/block_dev.c linux-2.6.20.ken/fs/block_dev.c --- linux-2.6.20-rc4/fs/block_dev.c 2007-01-06 21:45:51.000000000 -0800 +++ linux-2.6.20.ken/fs/block_dev.c 2007-01-10 19:54:53.000000000 -0800 @@ -190,6 +190,12 @@ static struct page *blk_get_page(unsigne return pvec->page[pvec->idx++]; } +/* return a page 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 */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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