> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk....@samsung.com]
> Sent: Wednesday, December 18, 2013 8:12 AM
> To: linux-fsde...@vger.kernel.org
> Cc: linux-ker...@vger.kernel.org; linux-f2fs-devel@lists.sourceforge.net
> Subject: Re: [f2fs-dev] [PATCH] f2fs: introduce a new direct_IO write path
>
> Change log from v1:
> o fix NOSPC error handling
>
> >From b8511a74fe98b67247a9feeed58441e8f5ffd705 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim <jaegeuk....@samsung.com>
> Date: Mon, 16 Dec 2013 19:04:05 +0900
> Subject: [PATCH] f2fs: introduce a new direct_IO write path
> Cc: linux-fsde...@vger.kernel.org, linux-ker...@vger.kernel.org,
> linux-f2fs-devel@lists.sourceforge.net
>
> Previously, f2fs doesn't support direct IOs with high performance, which
> throws
> every write requests via the buffered write path, resulting in highly
> performance degradation due to memory opeations like copy_from_user.
>
> This patch introduces a new direct IO path in which every write requests
> are
> processed by generic blockdev_direct_IO() with enhanced get_block
> function.
>
> The get_data_block() in f2fs handles:
> 1. if original data blocks are allocates, then give them to blockdev.
> 2. otherwise,
> a. preallocate requested block addresses
> b. do not use extent cache for better performance
> c. give the block addresses to blockdev
>
> This policy induces that:
> - new allocated data are sequentially written to the disk
> - updated data are randomly written to the disk.
> - f2fs gives consistency on its file meta, not file data.
Looks Nice!
>
> Signed-off-by: Jaegeuk Kim <jaegeuk....@samsung.com>
Reviewed-by: Chao Yu <chao2...@samsung.com>
> +
> + end_offset = IS_INODE(dn.node_page) ?
> + ADDRS_PER_INODE(F2FS_I(inode)) : ADDRS_PER_BLOCK;
> + bh_result->b_size = (((size_t)1) << blkbits);
> + dn.ofs_in_node++;
> + pgofs++;
> +
> +get_next:
> + if (dn.ofs_in_node >= end_offset) {
> + if (allocated)
> + sync_inode_page(&dn);
> + allocated = false;
if (allocated) {
sync_inode_page(&dn);
allocated = false;
}
Certainly, it's really not a big deal. :)
Thanks
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