From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Matthew Wilcox <willy@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
Matthew Wilcox <matthew.r.wilcox@intel.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-ext4@vger.kernel.org
Subject: Re: [PATCH v5 22/22] XIP: Add support for unwritten extents
Date: Thu, 23 Jan 2014 12:13:48 -0700 (MST) [thread overview]
Message-ID: <alpine.OSX.2.00.1401231212120.75514@scrumpy> (raw)
In-Reply-To: <20140123120829.GF5722@linux.intel.com>
On Thu, 23 Jan 2014, Matthew Wilcox wrote:
> On Wed, Jan 22, 2014 at 03:51:56PM -0700, Ross Zwisler wrote:
> > > + if (hole) {
> > > addr = NULL;
> > > - hole = true;
> > > size = bh->b_size;
> > > + } else {
> > > + unsigned first;
> > > + retval = xip_get_addr(inode, bh, &addr);
> > > + if (retval < 0)
> > > + break;
> > > + size = retval;
> > > + first = offset - (block << inode->i_blkbits);
> > > + if (buffer_unwritten(bh))
> > > + memset(addr, 0, first);
> > > + addr += first;
> >
> > + size -= first;
> >
> > This is needed so that we don't overrun the XIP buffer we are given in the
> > event that our user buffer >= our XIP buffer and the start of our I/O isn't
> > block aligned.
>
> You're right! Thank you! However, we also need it for the hole ==
> true case, don't we? So maybe something like this, incrementally on top of
> patch 22/22:
>
> P.S. Can someone come up with a better name for this variable than 'first'?
> I'd usually use 'offset', but that's already taken. 'annoying_bit' seems a
> bit judgemental. 'misaligned', maybe? 'skip' or 'seek' like dd uses?
>
> diff --git a/fs/xip.c b/fs/xip.c
> index 92157ff..1ae00db 100644
> --- a/fs/xip.c
> +++ b/fs/xip.c
> @@ -103,6 +103,7 @@ static ssize_t xip_io(int rw, struct inode *inode, const struct iovec *iov,
>
> if (max == offset) {
> sector_t block = offset >> inode->i_blkbits;
> + unsigned first = offset - (block << inode->i_blkbits);
> long size;
> memset(bh, 0, sizeof(*bh));
> bh->b_size = ALIGN(end - offset, PAGE_SIZE);
> @@ -121,14 +122,12 @@ static ssize_t xip_io(int rw, struct inode *inode, const struct iovec *iov,
>
> if (hole) {
> addr = NULL;
> - size = bh->b_size;
> + size = bh->b_size - first;
> } else {
> - unsigned first;
> retval = xip_get_addr(inode, bh, &addr);
> if (retval < 0)
> break;
> - size = retval;
> - first = offset - (block << inode->i_blkbits);
> + size = retval - first;
> if (buffer_unwritten(bh))
> memset(addr, 0, first);
> addr += first;
Yep, this seems right to me.
Maybe "misalignment"? Seems more descriptive (if a bit long), but I don't
know if there are other, better existing conventions.
- Ross
next prev parent reply other threads:[~2014-01-23 19:13 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-16 1:24 [PATCH v5 00/22] Rewrite XIP code and add XIP support to ext4 Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 01/22] Fix XIP fault vs truncate race Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 02/22] Allow page fault handlers to perform the COW Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 03/22] axonram: Fix bug in direct_access Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 04/22] Change direct_access calling convention Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 05/22] Introduce IS_XIP(inode) Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 06/22] Treat XIP like O_DIRECT Matthew Wilcox
2014-01-31 16:59 ` Jan Kara
2014-01-16 1:24 ` [PATCH v5 07/22] Rewrite XIP page fault handling Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 08/22] Change xip_truncate_page to take a get_block parameter Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 09/22] Remove mm/filemap_xip.c Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 10/22] Remove get_xip_mem Matthew Wilcox
2014-01-16 1:46 ` Randy Dunlap
2014-01-27 13:26 ` Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 11/22] Replace ext2_clear_xip_target with xip_clear_blocks Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 12/22] ext2: Remove ext2_xip_verify_sb() Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 13/22] ext2: Remove ext2_use_xip Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 14/22] ext2: Remove xip.c and xip.h Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 15/22] Remove CONFIG_EXT2_FS_XIP Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 16/22] ext2: Remove ext2_aops_xip Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 17/22] xip: Add xip_zero_page_range Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 18/22] ext4: Make ext4_block_zero_page_range static Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 19/22] ext4: Add XIP functionality Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 20/22] ext4: Fix typos Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 21/22] xip: Add reporting of major faults Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 22/22] XIP: Add support for unwritten extents Matthew Wilcox
[not found] ` <CEFDA737.22F87%matthew.r.wilcox@intel.com>
2014-01-17 0:00 ` [PATCH v5 19/22] ext4: Add XIP functionality Ross Zwisler
[not found] ` <CEFD7DAD.22F65%matthew.r.wilcox@intel.com>
2014-01-22 22:51 ` [PATCH v5 22/22] XIP: Add support for unwritten extents Ross Zwisler
2014-01-23 12:08 ` Matthew Wilcox
2014-01-23 19:13 ` Ross Zwisler [this message]
[not found] ` <CF0C370C.235F1%willy@linux.intel.com>
2014-01-27 23:32 ` Ross Zwisler
2014-01-28 3:49 ` Matthew Wilcox
2014-01-23 7:48 ` [PATCH v5 00/22] Rewrite XIP code and add XIP support to ext4 Dave Chinner
2014-01-23 7:53 ` Dave Chinner
2014-01-23 9:01 ` Dave Chinner
2014-01-23 12:12 ` Wilcox, Matthew R
2014-01-28 6:06 ` Dave Chinner
2014-01-30 6:42 ` Dave Chinner
2014-01-30 9:25 ` Dave Chinner
2014-01-31 3:06 ` Dave Chinner
2014-01-31 5:45 ` Ross Zwisler
2014-01-31 13:04 ` Dave Chinner
[not found] ` <CF1FF3EB.24114%matthew.r.wilcox@intel.com>
2014-02-11 23:12 ` [PATCH v5 19/22] ext4: Add XIP functionality Ross Zwisler
2014-02-13 0:00 ` Ross Zwisler
[not found] ` <CF215477.24281%matthew.r.wilcox@intel.com>
2014-02-12 23:53 ` [PATCH v5 06/22] Treat XIP like O_DIRECT Ross Zwisler
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.OSX.2.00.1401231212120.75514@scrumpy \
--to=ross.zwisler@linux.intel.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=matthew.r.wilcox@intel.com \
--cc=willy@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).