Hi Chao, On Fri, Dec 25, 2015 at 09:18:06AM +0800, Chao Yu wrote: > Hi Jaegeuk, > > > -----Original Message----- > > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx] > > Sent: Friday, December 25, 2015 5:52 AM > > To: Chao Yu > > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > Subject: Re: [f2fs-dev] [PATCH 3/4] f2fs: avoid f2fs_lock_op in f2fs_write_begin > > > > Hi Chao, > > > > On Thu, Dec 24, 2015 at 12:33:50PM -0800, Jaegeuk Kim wrote: > > > Hi Chao, > > > > > > On Thu, Dec 24, 2015 at 01:50:32PM +0800, Chao Yu wrote: > > > > Hi Jaegeuk, > > > > > > > > > -----Original Message----- > > > > > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx] > > > > > Sent: Thursday, December 24, 2015 10:15 AM > > > > > To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; > > > > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > > > > Cc: Jaegeuk Kim > > > > > Subject: [f2fs-dev] [PATCH 3/4] f2fs: avoid f2fs_lock_op in f2fs_write_begin > > > > > > > > > > If f2fs_write_begin is to update data, we can bypass calling f2fs_lock_op() in > > > > > order to avoid the checkpoint latency in the write syscall. > > > > > > > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> > > > > > --- > > > > > fs/f2fs/data.c | 43 ++++++++++++++++++++++++++++++++++--------- > > > > > 1 file changed, 34 insertions(+), 9 deletions(-) > > > > > > > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > > > > index 49092da..d53cf4f 100644 > > > > > --- a/fs/f2fs/data.c > > > > > +++ b/fs/f2fs/data.c > > > > > @@ -1418,10 +1418,16 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi, > > > > > pgoff_t index = page->index; > > > > > struct dnode_of_data dn; > > > > > struct page *ipage; > > > > > + bool locked = false; > > > > > + struct extent_info ei; > > > > > int err = 0; > > > > > > > > > > - f2fs_lock_op(sbi); > > > > > - > > > > > + if (f2fs_has_inline_data(inode) || > > > > > + (pos & PAGE_CACHE_MASK) >= i_size_read(inode)) { > > > > > + f2fs_lock_op(sbi); > > > > > + locked = true; > > > > > + } > > > > > +restart: > > > > > /* check inline_data */ > > > > > ipage = get_node_page(sbi, inode->i_ino); > > > > > if (IS_ERR(ipage)) { > > > > > @@ -1436,22 +1442,41 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi, > > > > > read_inline_data(page, ipage); > > > > > set_inode_flag(F2FS_I(inode), FI_DATA_EXIST); > > > > > sync_inode_page(&dn); > > > > > - goto done; > > > > > } else { > > > > > err = f2fs_convert_inline_page(&dn, page); > > > > > if (err) > > > > > - goto err_out; > > > > > + goto out; > > > > > + err = f2fs_get_block(&dn, index); > > > > > > > > Seems after f2fs_convert_inline_page, data_blkaddr and node_changed should > > > > have been set, so f2fs_get_block could be removed here. > > > > > > I don't think so. The inline_data treats with 0'th index only. > > > In order to handle non-zero index, we should do f2fs_get_block. > > non-zero index page should have been handled before grab_cache_page_write_begin. > We won't encounter such case here. Alright. So, let me go with: if (dn.data_blkaddr == NULL_ADDR) err = f2fs_get_block(); Thanks, > > > > Oh, if you meant zero index case only, we can do that like this. > > > > > > if (index) > > > err = f2fs_get_block(); > > > > Actually, we need > > if (index || !dn.data_blkaddr) > > err = f2fs_get_block(); > > > > Since f2fs_convert_inline_page can return right away, if there is > > no data in inline_data space. > > Yes, that's the case we should handle. :) > > Thanks, > > > > > Thanks, > > > > > > > > > > > > > > + } > > > > > + } else if (locked) { > > > > > + err = f2fs_get_block(&dn, index); > > > > > + } else { > > > > > + if (f2fs_lookup_extent_cache(inode, index, &ei)) { > > > > > + dn.data_blkaddr = ei.blk + index - ei.fofs; > > > > > + } else { > > > > > + bool restart = false; > > > > > + > > > > > + /* hole case */ > > > > > + err = get_dnode_of_data(&dn, index, LOOKUP_NODE); > > > > > > > > Better to handle error case like -ENOMEM or -EIO. > > > > > > I think we can just give another chance at this moment and let f2fs_get_block() > > > handle that in the next round. > > > > > > Thanks, > > > > > > > > > > > Thanks, > > > > > > > > > + if (err || (!err && dn.data_blkaddr == NULL_ADDR)) > > > > > + restart = true; > > > > > + if (restart) { > > > > > + f2fs_put_dnode(&dn); > > > > > + f2fs_lock_op(sbi); > > > > > + locked = true; > > > > > + goto restart; > > > > > + } > > > > > } > > > > > } > > > > > - err = f2fs_get_block(&dn, index); > > > > > -done: > > > > > + > > > > > /* convert_inline_page can make node_changed */ > > > > > *blk_addr = dn.data_blkaddr; > > > > > *node_changed = dn.node_changed; > > > > > -err_out: > > > > > +out: > > > > > f2fs_put_dnode(&dn); > > > > > unlock_out: > > > > > - f2fs_unlock_op(sbi); > > > > > + if (locked) > > > > > + f2fs_unlock_op(sbi); > > > > > return err; > > > > > } > > > > > > > > > > @@ -1488,7 +1513,7 @@ repeat: > > > > > > > > > > *pagep = page; > > > > > > > > > > - err = prepare_write_begin(sbi, page, pos + len, > > > > > + err = prepare_write_begin(sbi, page, pos, len, > > > > > &blkaddr, &need_balance); > > > > > if (err) > > > > > goto fail; > > > > > -- > > > > > 2.5.4 (Apple Git-61) > > > > > > > > > > > > > > > ------------------------------------------------------------------------------ > > > > > _______________________________________________ > > > > > Linux-f2fs-devel mailing list > > > > > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > > > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > > > > > ------------------------------------------------------------------------------ > > > _______________________________________________ > > > Linux-f2fs-devel mailing list > > > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel -- 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
