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Date: Thu, 7 Jun 2018 15:50:03 +0200
From: Andreas Grünbacher <andreas.gruenbacher@...il.com>
To: Christoph Hellwig <hch@....de>
Cc: Andreas Gruenbacher <agruenba@...hat.com>,
linux-xfs@...r.kernel.org, Dan Williams <dan.j.williams@...el.com>,
Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
cluster-devel <cluster-devel@...hat.com>,
linux-ext4 <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 5/6] iomap: generic inline data handling
2018-06-06 12:40 GMT+02:00 Christoph Hellwig <hch@....de>:
> From: Andreas Gruenbacher <agruenba@...hat.com>
>
> Add generic inline data handling by adding a pointer to the inline data
> region to struct iomap. When handling a buffered IOMAP_INLINE write,
> iomap_write_begin will copy the current inline data from the inline data
> region into the page cache, and iomap_write_end will copy the changes in
> the page cache back to the inline data region.
>
> This doesn't cover inline data reads and direct I/O yet because so far,
> we have no users.
>
> Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
> [hch: small cleanups to better fit in with other iomap work]
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
> fs/iomap.c | 62 +++++++++++++++++++++++++++++++++++++++++++++------
> include/linux/iomap.h | 1 +
> 2 files changed, 56 insertions(+), 7 deletions(-)
>
> diff --git a/fs/iomap.c b/fs/iomap.c
> index f428baa32185..f2a491b98b7c 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -116,6 +116,26 @@ iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
> truncate_pagecache_range(inode, max(pos, i_size), pos + len);
> }
>
> +static void
> +iomap_read_inline_data(struct inode *inode, struct page *page,
> + struct iomap *iomap)
> +{
> + size_t size = i_size_read(inode);
> + void *addr;
> +
> + if (PageUptodate(page))
> + return;
> +
> + BUG_ON(page->index);
> + BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
> +
> + addr = kmap_atomic(page);
> + memcpy(addr, iomap->inline_data, size);
> + memset(addr + size, 0, PAGE_SIZE - size);
> + kunmap_atomic(addr);
> + SetPageUptodate(page);
> +}
Can you please move iomap_read_inline_data above iomap_write_failed in
fs/iomap.c so that it will end up above the readpage code? We'll need
iomap_read_inline_data in the readpage code.
> static int
> iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
> struct page **pagep, struct iomap *iomap)
> @@ -133,7 +153,11 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
> if (!page)
> return -ENOMEM;
>
> - status = __block_write_begin_int(page, pos, len, NULL, iomap);
> + if (iomap->type == IOMAP_INLINE)
> + iomap_read_inline_data(inode, page, iomap);
> + else
> + status = __block_write_begin_int(page, pos, len, NULL, iomap);
> +
> if (unlikely(status)) {
> unlock_page(page);
> put_page(page);
> @@ -146,14 +170,37 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
> return status;
> }
>
> +static int
> +iomap_write_end_inline(struct inode *inode, struct page *page,
> + struct iomap *iomap, loff_t pos, unsigned copied)
> +{
> + void *addr;
> +
> + WARN_ON_ONCE(!PageUptodate(page));
> + BUG_ON(pos + copied > PAGE_SIZE - offset_in_page(iomap->inline_data));
> +
> + addr = kmap_atomic(page);
> + memcpy(iomap->inline_data + pos, addr + pos, copied);
> + kunmap_atomic(addr);
> +
> + mark_inode_dirty(inode);
> + __generic_write_end(inode, pos, copied, page);
> + return copied;
> +}
> +
> static int
> iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
> - unsigned copied, struct page *page)
> + unsigned copied, struct page *page, struct iomap *iomap)
> {
> int ret;
>
> - ret = generic_write_end(NULL, inode->i_mapping, pos, len,
> - copied, page, NULL);
> + if (iomap->type == IOMAP_INLINE) {
> + ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
> + } else {
> + ret = generic_write_end(NULL, inode->i_mapping, pos, len,
> + copied, page, NULL);
> + }
> +
> if (ret < len)
> iomap_write_failed(inode, pos, len);
> return ret;
> @@ -208,7 +255,8 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
>
> flush_dcache_page(page);
>
> - status = iomap_write_end(inode, pos, bytes, copied, page);
> + status = iomap_write_end(inode, pos, bytes, copied, page,
> + iomap);
> if (unlikely(status < 0))
> break;
> copied = status;
> @@ -302,7 +350,7 @@ iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
>
> WARN_ON_ONCE(!PageUptodate(page));
>
> - status = iomap_write_end(inode, pos, bytes, bytes, page);
> + status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
> if (unlikely(status <= 0)) {
> if (WARN_ON_ONCE(status == 0))
> return -EIO;
> @@ -354,7 +402,7 @@ static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
> zero_user(page, offset, bytes);
> mark_page_accessed(page);
>
> - return iomap_write_end(inode, pos, bytes, bytes, page);
> + return iomap_write_end(inode, pos, bytes, bytes, page, iomap);
> }
>
> static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index 212f4d59bcbf..69ef622f650e 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -56,6 +56,7 @@ struct iomap {
> union {
> struct block_device *bdev;
> struct dax_device *dax_dev;
> + void *inline_data;
> };
> };
>
> --
> 2.14.2
>
Thanks,
Andreas
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