From: Jeff Moyer <jmoyer@redhat.com>
To: "Wilcox\, Matthew R" <matthew.r.wilcox@intel.com>
Cc: "linda.knippers\@hp.com" <linda.knippers@hp.com>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-fsdevel\@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: regression introduced by "block: Add support for DAX reads/writes to block devices"
Date: Thu, 06 Aug 2015 17:30:56 -0400 [thread overview]
Message-ID: <x49fv3wgl4f.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <100D68C7BA14664A8938383216E40DE04091408C@FMSMSX114.amr.corp.intel.com> (Matthew R. Wilcox's message of "Thu, 6 Aug 2015 14:21:24 +0000")
"Wilcox, Matthew R" <matthew.r.wilcox@intel.com> writes:
> I think I see the problem. I'm kind of wrapped up in other things
> right now; can you try replacing the line in dax_io():
>
> - bh->b_size = PAGE_ALIGN(end - pos);
> + bh->b_size = ALIGN(end - pos, 1 << blkbits);
This works for me. If it looks okay to others, I'll submit a properly
signed-off patch.
Cheers,
Jeff
diff --git a/fs/dax.c b/fs/dax.c
index a7f77e1..b6c4f93 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -98,6 +98,10 @@ static bool buffer_size_valid(struct buffer_head *bh)
return bh->b_state != 0;
}
+/*
+ * This function assumes file system block size (represented by
+ * inode->i_blkbits) is less than or equal to the system page size.
+ */
static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
loff_t start, loff_t end, get_block_t get_block,
struct buffer_head *bh)
@@ -117,9 +121,15 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
if (pos == max) {
unsigned blkbits = inode->i_blkbits;
sector_t block = pos >> blkbits;
- unsigned first = pos - (block << blkbits);
+ long page = pos >> PAGE_SHIFT;
+ unsigned first; /* byte offset into block */
long size;
+ /* we can only map entire pages */
+ if (pos & (PAGE_SIZE-1))
+ block = page << (PAGE_SHIFT - blkbits);
+ first = pos - (block << blkbits);
+
if (pos == bh_max) {
bh->b_size = PAGE_ALIGN(end - pos);
bh->b_state = 0;
next prev parent reply other threads:[~2015-08-06 22:25 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-05 20:19 regression introduced by "block: Add support for DAX reads/writes to block devices" Jeff Moyer
2015-08-05 22:01 ` Dave Chinner
2015-08-06 1:42 ` Linda Knippers
2015-08-06 3:24 ` Dave Chinner
2015-08-06 7:52 ` Boaz Harrosh
2015-08-06 20:34 ` Dave Chinner
2015-08-09 8:52 ` Boaz Harrosh
2015-08-10 16:32 ` Linda Knippers
2015-08-10 21:27 ` Dave Chinner
2015-08-10 23:04 ` Linda Knippers
2015-08-06 14:21 ` Wilcox, Matthew R
2015-08-06 15:33 ` Jeff Moyer
2015-08-06 15:51 ` Wilcox, Matthew R
2015-08-06 21:30 ` Jeff Moyer [this message]
2015-08-07 18:11 ` Wilcox, Matthew R
2015-08-07 20:41 ` Jeff Moyer
2015-08-10 7:42 ` Boaz Harrosh
2015-08-12 21:11 ` Jeff Moyer
2015-08-13 5:32 ` Boaz Harrosh
2015-08-13 14:00 ` Jeff Moyer
2015-08-13 16:42 ` Linda Knippers
2015-08-13 17:14 ` Jeff Moyer
2015-08-13 17:52 ` Linda Knippers
2015-08-13 18:19 ` Jeff Moyer
2015-08-13 19:32 ` Wilcox, Matthew R
2015-08-14 16:28 ` Dan Williams
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