Hi, 2013-12-20 (금), 10:14 +0800, Chao Yu: > Hi Kim, > > One comment as following: > > > -----Original Message----- > > From: Jaegeuk Kim [mailto:jaegeuk.kim@xxxxxxxxxxx] > > Sent: Wednesday, December 18, 2013 8:12 AM > > To: linux-fsdevel@xxxxxxxxxxxxxxx > > Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > 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.kim@xxxxxxxxxxx> > > Date: Mon, 16 Dec 2013 19:04:05 +0900 > > Subject: [PATCH] f2fs: introduce a new direct_IO write path > > Cc: linux-fsdevel@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > > > 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. > > > > Signed-off-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx> > > --- > > fs/f2fs/data.c | 152 > > ++++++++++++++++++++++++++++++++++++++++-------------- > > fs/f2fs/f2fs.h | 2 + > > fs/f2fs/segment.c | 23 ++++++--- > > 3 files changed, 129 insertions(+), 48 deletions(-) > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index 15956fa..a0950bc 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -570,74 +570,151 @@ repeat: > > return page; > > } > > > > +static int __allocate_data_block(struct dnode_of_data *dn) > > +{ > > + struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb); > > + struct f2fs_summary sum; > > + block_t new_blkaddr; > > + struct node_info ni; > > + int type; > > + > > + if (unlikely(is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC))) > > + return -EPERM; > > + if (unlikely(!inc_valid_block_count(sbi, dn->inode, 1))) > > + return -ENOSPC; > > + > > + __set_data_blkaddr(dn, NEW_ADDR); > > + dn->data_blkaddr = NEW_ADDR; > > + > > + get_node_info(sbi, dn->nid, &ni); > > + set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version); > > + > > + type = CURSEG_WARM_DATA; > > If so, our cold data will be written to WARM_DATA segment. > How about check segment type here? Actually, I'm not sure this kind of data requested through direct IOs are cold or hot data. But I just intended to gather such the direct IO'ed data into one type of log, not separately. So, I selected WARM_DATA by the fact that such the data will be frequently updated through direct IO either. Thanks, > > > + > > + allocate_data_block(sbi, NULL, NULL_ADDR, &new_blkaddr, &sum, type); > > + > > + /* direct IO doesn't use extent cache to maximize the performance */ > > + set_inode_flag(F2FS_I(dn->inode), FI_NO_EXTENT); > > + update_extent_cache(new_blkaddr, dn); > > + clear_inode_flag(F2FS_I(dn->inode), FI_NO_EXTENT); > > + > > + dn->data_blkaddr = new_blkaddr; > > + return 0; > > +} > > + > > [snip] > -- Jaegeuk Kim Samsung -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
