Messages in this thread Patch in this message |  | | Subject | Re: [f2fs-dev] [PATCH v3] f2fs: don't use GFP_ZERO for page caches | From | Chao Yu <> | Date | Tue, 10 Apr 2018 14:33:19 +0800 |
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On 2018/4/10 11:29, Jaegeuk Kim wrote: > Change log from v2: > - consider IO error case when dealing with metapage > - memset by fill_node_footer > > Change log from v1: > - don't memset for recovered page > > Related to https://lkml.org/lkml/2018/4/8/661 > > Sometimes, we need to write meta data to new allocated block address, > then we will allocate a zeroed page in inner inode's address space, and > fill partial data in it, and leave other place with zero value which means > some fields are initial status. > > There are two inner inodes (meta inode and node inode) setting __GFP_ZERO, > I have just checked them, for both of them, we can avoid using __GFP_ZERO, > and do initialization by ourselves to avoid unneeded/redundant zeroing > from mm. > > Cc: <stable@vger.kernel.org> > Signed-off-by: Chao Yu <yuchao0@huawei.com> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > --- > fs/f2fs/checkpoint.c | 4 +++- > fs/f2fs/inode.c | 4 ++-- > fs/f2fs/segment.c | 3 +++ > fs/f2fs/segment.h | 1 + > 4 files changed, 9 insertions(+), 3 deletions(-) > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > index bf779461df13..2e23b953d304 100644 > --- a/fs/f2fs/checkpoint.c > +++ b/fs/f2fs/checkpoint.c > @@ -100,8 +100,10 @@ static struct page *__get_meta_page(struct f2fs_sb_info *sbi, pgoff_t index, > * readonly and make sure do not write checkpoint with non-uptodate > * meta page. > */ > - if (unlikely(!PageUptodate(page))) > + if (unlikely(!PageUptodate(page))) { > + memset(page_address(page), 0, PAGE_SIZE); > f2fs_stop_checkpoint(sbi, false); > + } > out: > return page; > } > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c > index 417c9dcd0269..87535bf63421 100644 > --- a/fs/f2fs/inode.c > +++ b/fs/f2fs/inode.c > @@ -320,10 +320,10 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino) > make_now: > if (ino == F2FS_NODE_INO(sbi)) { > inode->i_mapping->a_ops = &f2fs_node_aops; > - mapping_set_gfp_mask(inode->i_mapping, GFP_F2FS_ZERO); > + mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS); > } else if (ino == F2FS_META_INO(sbi)) { > inode->i_mapping->a_ops = &f2fs_meta_aops; > - mapping_set_gfp_mask(inode->i_mapping, GFP_F2FS_ZERO); > + mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS); > } else if (S_ISREG(inode->i_mode)) { > inode->i_op = &f2fs_file_inode_operations; > inode->i_fop = &f2fs_file_operations; > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index a4b8e3e24ccb..1f5db557ab96 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -2021,6 +2021,7 @@ static void write_current_sum_page(struct f2fs_sb_info *sbi, > struct f2fs_summary_block *dst; > > dst = (struct f2fs_summary_block *)page_address(page); > + memset(dst, 0, PAGE_SIZE);
We will fill all summary page later, so we don't need initialize it?
> > mutex_lock(&curseg->curseg_mutex); > > @@ -3117,6 +3118,7 @@ static void write_compacted_summaries(struct f2fs_sb_info *sbi, block_t blkaddr) > > page = grab_meta_page(sbi, blkaddr++); > kaddr = (unsigned char *)page_address(page); > + memset(kaddr, 0, PAGE_SIZE);
I checked here, we will not use uninitialized space due to:
read_compacted_summaries() { ... if (offset + SUMMARY_SIZE <= PAGE_SIZE - SUM_FOOTER_SIZE) continue; ... }
Are we safe here?
> > /* Step 1: write nat cache */ > seg_i = CURSEG_I(sbi, CURSEG_HOT_DATA); > @@ -3141,6 +3143,7 @@ static void write_compacted_summaries(struct f2fs_sb_info *sbi, block_t blkaddr) > if (!page) { > page = grab_meta_page(sbi, blkaddr++); > kaddr = (unsigned char *)page_address(page); > + memset(kaddr, 0, PAGE_SIZE);
Ditto.
> written_size = 0; > } > summary = (struct f2fs_summary *)(kaddr + written_size); > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h > index 3325d0769723..492ad0c86fa9 100644 > --- a/fs/f2fs/segment.h > +++ b/fs/f2fs/segment.h > @@ -375,6 +375,7 @@ static inline void seg_info_to_sit_page(struct f2fs_sb_info *sbi, > int i; > > raw_sit = (struct f2fs_sit_block *)page_address(page); > + memset(raw_sit, 0, PAGE_SIZE);
I suspect that root cause of panic is that we don't memset here?
Thanks,
> for (i = 0; i < end - start; i++) { > rs = &raw_sit->entries[i]; > se = get_seg_entry(sbi, start + i); >
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