From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: Christoph Hellwig <hch@lst.de>, linux-xfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 31/33] iomap: add support for sub-pagesize buffered I/O without buffer heads
Date: Mon, 14 May 2018 11:00:08 -0500 [thread overview]
Message-ID: <eebcc4bf-f646-edc6-264b-124b3880f3cb@suse.de> (raw)
In-Reply-To: <20180509074830.16196-32-hch@lst.de>
On 05/09/2018 02:48 AM, Christoph Hellwig wrote:
> After already supporting a simple implementation of buffered writes for
> the blocksize == PAGE_SIZE case in the last commit this adds full support
> even for smaller block sizes. There are three bits of per-block
> information in the buffer_head structure that really matter for the iomap
> read and write path:
>
> - uptodate status (BH_uptodate)
> - marked as currently under read I/O (BH_Async_Read)
> - marked as currently under write I/O (BH_Async_Write)
>
> Instead of having new per-block structures this now adds a per-page
> structure called struct iomap_page to track this information in a slightly
> different form:
>
> - a bitmap for the per-block uptodate status. For worst case of a 64k
> page size system this bitmap needs to contain 128 bits. For the
> typical 4k page size case it only needs 8 bits, although we still
> need a full unsigned long due to the way the atomic bitmap API works.
> - two atomic_t counters are used to track the outstanding read and write
> counts
>
> There is quite a bit of boilerplate code as the buffered I/O path uses
> various helper methods, but the actual code is very straight forward.
>
> In this commit the code can't actually be used yet, as we need to
> switch from the old implementation to the new one together with the
> XFS writeback code.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/iomap.c | 262 +++++++++++++++++++++++++++++++++++++-----
> include/linux/iomap.h | 32 ++++++
> 2 files changed, 264 insertions(+), 30 deletions(-)
>
> diff --git a/fs/iomap.c b/fs/iomap.c
> index a3861945504f..4e7ac6aa88ef 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -17,6 +17,7 @@
> #include <linux/iomap.h>
> #include <linux/uaccess.h>
> #include <linux/gfp.h>
> +#include <linux/migrate.h>
> #include <linux/mm.h>
> #include <linux/mm_inline.h>
> #include <linux/swap.h>
> @@ -109,6 +110,107 @@ iomap_block_needs_zeroing(struct inode *inode, loff_t pos, struct iomap *iomap)
> return iomap->type != IOMAP_MAPPED || pos > i_size_read(inode);
> }
>
> +static struct iomap_page *
> +iomap_page_create(struct inode *inode, struct page *page)
> +{
> + struct iomap_page *iop = to_iomap_page(page);
> +
> + if (iop || i_blocksize(inode) == PAGE_SIZE)
> + return iop;
Why is this an equal comparison operator? Shouldn't this be >= to
include filesystem blocksize greater than PAGE_SIZE?
--
Goldwyn
next prev parent reply other threads:[~2018-05-14 16:00 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180509074830.16196-1-hch@lst.de>
2018-05-09 7:47 ` [PATCH 01/33] block: add a lower-level bio_add_page interface Christoph Hellwig
2018-05-09 15:12 ` Matthew Wilcox
2018-05-10 6:40 ` Christoph Hellwig
2018-05-10 21:49 ` Andreas Dilger
2018-05-11 6:29 ` Christoph Hellwig
2018-05-15 16:47 ` Jens Axboe
2018-05-10 8:52 ` Ming Lei
2018-05-11 6:24 ` Christoph Hellwig
2018-05-16 5:06 ` Ritesh Harjani
2018-05-16 18:05 ` Christoph Hellwig
2018-05-17 4:18 ` Ritesh Harjani
2018-05-09 7:47 ` [PATCH 02/33] fs: factor out a __generic_write_end helper Christoph Hellwig
2018-05-09 15:15 ` Matthew Wilcox
2018-05-10 6:40 ` Christoph Hellwig
2018-05-09 7:48 ` [PATCH 03/33] fs: move page_cache_seek_hole_data to iomap.c Christoph Hellwig
2018-05-09 7:48 ` [PATCH 04/33] fs: remove the buffer_unwritten check in page_seek_hole_data Christoph Hellwig
2018-05-17 11:33 ` Andreas Grünbacher
2018-05-09 7:48 ` [PATCH 05/33] fs: use ->is_partially_uptodate in page_cache_seek_hole_data Christoph Hellwig
2018-05-09 7:48 ` [PATCH 06/33] mm: give the 'ret' variable a better name __do_page_cache_readahead Christoph Hellwig
2018-05-09 15:45 ` Matthew Wilcox
2018-05-10 6:41 ` Christoph Hellwig
2018-05-09 7:48 ` [PATCH 07/33] mm: split ->readpages calls to avoid non-contiguous pages lists Christoph Hellwig
2018-05-09 15:46 ` Matthew Wilcox
2018-05-09 7:48 ` [PATCH 08/33] iomap: use __bio_add_page in iomap_dio_zero Christoph Hellwig
2018-05-09 7:48 ` [PATCH 09/33] iomap: add a iomap_sector helper Christoph Hellwig
2018-05-09 7:48 ` [PATCH 10/33] iomap: add an iomap-based bmap implementation Christoph Hellwig
2018-05-09 16:46 ` Darrick J. Wong
2018-05-10 6:42 ` Christoph Hellwig
2018-05-10 15:08 ` Darrick J. Wong
2018-05-11 6:25 ` Christoph Hellwig
2018-05-12 1:56 ` Darrick J. Wong
2018-05-09 7:48 ` [PATCH 11/33] iomap: add an iomap-based readpage and readpages implementation Christoph Hellwig
2018-05-10 1:17 ` Dave Chinner
2018-05-10 6:44 ` Christoph Hellwig
2018-05-09 7:48 ` [PATCH 12/33] xfs: use iomap_bmap Christoph Hellwig
2018-05-09 7:48 ` [PATCH 13/33] xfs: use iomap for blocksize == PAGE_SIZE readpage and readpages Christoph Hellwig
2018-05-09 7:48 ` [PATCH 14/33] xfs: simplify xfs_bmap_punch_delalloc_range Christoph Hellwig
2018-05-09 7:48 ` [PATCH 15/33] xfs: simplify xfs_aops_discard_page Christoph Hellwig
2018-05-09 7:48 ` [PATCH 16/33] xfs: move locking into xfs_bmap_punch_delalloc_range Christoph Hellwig
2018-05-09 7:48 ` [PATCH 17/33] xfs: make xfs_writepage_map extent map centric Christoph Hellwig
2018-05-09 7:48 ` [PATCH 18/33] xfs: remove the now unused XFS_BMAPI_IGSTATE flag Christoph Hellwig
2018-05-09 7:48 ` [PATCH 19/33] xfs: remove xfs_reflink_find_cow_mapping Christoph Hellwig
2018-05-09 7:48 ` [PATCH 20/33] xfs: remove xfs_reflink_trim_irec_to_next_cow Christoph Hellwig
2018-05-09 7:48 ` [PATCH 21/33] xfs: simplify xfs_map_blocks by using xfs_iext_lookup_extent directly Christoph Hellwig
2018-05-09 7:48 ` [PATCH 22/33] xfs: don't clear imap_valid for a non-uptodate buffers Christoph Hellwig
2018-05-09 7:48 ` [PATCH 23/33] xfs: remove the imap_valid flag Christoph Hellwig
2018-05-09 7:48 ` [PATCH 24/33] xfs: don't look at buffer heads in xfs_add_to_ioend Christoph Hellwig
2018-05-09 7:48 ` [PATCH 25/33] xfs: move all writeback buffer_head manipulation into xfs_map_at_offset Christoph Hellwig
2018-05-09 7:48 ` [PATCH 26/33] xfs: allow writeback on pages without buffer heads Christoph Hellwig
2018-05-09 7:48 ` [PATCH 27/33] xfs: remove xfs_start_page_writeback Christoph Hellwig
2018-05-09 7:48 ` [PATCH 28/33] xfs: refactor the tail of xfs_writepage_map Christoph Hellwig
2018-05-09 7:48 ` [PATCH 29/33] xfs: do not set the page uptodate in xfs_writepage_map Christoph Hellwig
2018-05-09 7:48 ` [PATCH 30/33] iomap: add initial support for writes without buffer heads Christoph Hellwig
2018-05-09 7:48 ` [PATCH 31/33] iomap: add support for sub-pagesize buffered I/O " Christoph Hellwig
2018-05-14 16:00 ` Goldwyn Rodrigues [this message]
2018-05-15 7:26 ` Christoph Hellwig
2018-05-15 13:47 ` Goldwyn Rodrigues
2018-05-16 5:46 ` Dave Chinner
2018-05-09 7:48 ` [PATCH 32/33] xfs: add support for sub-pagesize writeback without buffer_heads Christoph Hellwig
2018-05-09 7:48 ` [PATCH 33/33] fs: remove __block_write_begin and iomap_to_bh Christoph Hellwig
2018-05-10 15:13 ` stop using buffer heads in xfs and iomap Darrick J. Wong
2018-05-11 6:22 ` Christoph Hellwig
2018-05-11 6:39 ` Darrick J. Wong
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