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Date: Mon, 31 Oct 2022 11:37:07 -0700
From: Daeho Jeong <daeho43@...il.com>
To: Chao Yu <chao@...nel.org>
Cc: linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net, kernel-team@...roid.com,
Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [f2fs-dev] [PATCH v5 1/2] f2fs: correct i_size change for atomic writes
On Fri, Oct 28, 2022 at 7:48 PM Chao Yu <chao@...nel.org> wrote:
>
> On 2022/10/19 1:00, Daeho Jeong wrote:
> > From: Daeho Jeong <daehojeong@...gle.com>
> >
> > We need to make sure i_size doesn't change until atomic write commit is
> > successful and restore it when commit is failed.
> >
> > Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
> > ---
> > v5: prevent only i_size update for atomic files when dirtying inode
> > v4: move i_size update after clearing atomic file flag in
> > f2fs_abort_atomic_write()
> > v3: make sure inode is clean while atomic writing
> > ---
> > fs/f2fs/f2fs.h | 8 ++++++++
> > fs/f2fs/file.c | 18 +++++++++++-------
> > fs/f2fs/inode.c | 5 ++++-
> > fs/f2fs/segment.c | 14 ++++++++++----
> > 4 files changed, 33 insertions(+), 12 deletions(-)
> >
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index e7e750e6b332..68d2a3383c38 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -764,6 +764,7 @@ enum {
> > FI_COMPRESS_RELEASED, /* compressed blocks were released */
> > FI_ALIGNED_WRITE, /* enable aligned write */
> > FI_COW_FILE, /* indicate COW file */
> > + FI_ATOMIC_COMMIT, /* indicate atomic commit completed except disk sync */
>
> How about FI_ATOMIC_WRITTEN or FI_ATOMIC_COMMITTED? which may be
> more readable?
Sounds reasonable. I will take FI_ATOMIC_COMMITTED.
>
> > FI_MAX, /* max flag, never be used */
> > };
> >
> > @@ -822,6 +823,7 @@ struct f2fs_inode_info {
> > unsigned int i_cluster_size; /* cluster size */
> >
> > unsigned int atomic_write_cnt;
> > + loff_t original_i_size; /* original i_size before atomic write */
> > };
> >
> > static inline void get_extent_info(struct extent_info *ext,
> > @@ -3072,6 +3074,8 @@ static inline void f2fs_i_blocks_write(struct inode *inode,
> > set_inode_flag(inode, FI_AUTO_RECOVER);
> > }
> >
> > +static inline bool f2fs_is_atomic_file(struct inode *inode);
> > +
> > static inline void f2fs_i_size_write(struct inode *inode, loff_t i_size)
> > {
> > bool clean = !is_inode_flag_set(inode, FI_DIRTY_INODE);
> > @@ -3081,6 +3085,10 @@ static inline void f2fs_i_size_write(struct inode *inode, loff_t i_size)
> > return;
> >
> > i_size_write(inode, i_size);
> > +
> > + if (f2fs_is_atomic_file(inode))
> > + return;
> > +
> > f2fs_mark_inode_dirty_sync(inode, true);
> > if (clean || recover)
> > set_inode_flag(inode, FI_AUTO_RECOVER);
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index ec9ee0f6d502..7ce629c95f4a 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -1991,6 +1991,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
> > struct f2fs_inode_info *fi = F2FS_I(inode);
> > struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> > struct inode *pinode;
> > + loff_t isize;
> > int ret;
> >
> > if (!inode_owner_or_capable(mnt_userns, inode))
> > @@ -2049,7 +2050,12 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
> > f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
> > goto out;
> > }
> > - f2fs_i_size_write(fi->cow_inode, i_size_read(inode));
> > +
> > + f2fs_write_inode(inode, NULL);
> > +
> > + isize = i_size_read(inode);
> > + fi->original_i_size = isize;
> > + f2fs_i_size_write(fi->cow_inode, isize);
> >
> > stat_inc_atomic_inode(inode);
> >
> > @@ -2087,16 +2093,14 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp)
> >
> > if (f2fs_is_atomic_file(inode)) {
> > ret = f2fs_commit_atomic_write(inode);
> > - if (ret)
> > - goto unlock_out;
> > -
> > - ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true);
> > if (!ret)
> > - f2fs_abort_atomic_write(inode, false);
> > + ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true);
> > +
> > + f2fs_abort_atomic_write(inode, ret);
> > } else {
> > ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false);
> > }
> > -unlock_out:
> > +
> > inode_unlock(inode);
> > mnt_drop_write_file(filp);
> > return ret;
> > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> > index 9f0d3864d9f1..044f132b87bc 100644
> > --- a/fs/f2fs/inode.c
> > +++ b/fs/f2fs/inode.c
> > @@ -621,9 +621,12 @@ void f2fs_update_inode(struct inode *inode, struct page *node_page)
> > ri->i_uid = cpu_to_le32(i_uid_read(inode));
> > ri->i_gid = cpu_to_le32(i_gid_read(inode));
> > ri->i_links = cpu_to_le32(inode->i_nlink);
> > - ri->i_size = cpu_to_le64(i_size_read(inode));
> > ri->i_blocks = cpu_to_le64(SECTOR_TO_BLOCK(inode->i_blocks) + 1);
> >
> > + if (!f2fs_is_atomic_file(inode) ||
> > + is_inode_flag_set(inode, FI_ATOMIC_COMMIT))
> > + ri->i_size = cpu_to_le64(i_size_read(inode));
>
> So we expect that below flow can update i_size correctly, right?
Yes, right.
Thanks,
>
> - f2fs_ioc_commit_atomic_write
> - f2fs_do_sync_file
> - f2fs_skip_inode_update
> - f2fs_write_inode
> - f2fs_update_inode_page
> - f2fs_update_inode
>
> Thanks,
>
> > +
> > if (et) {
> > read_lock(&et->lock);
> > set_raw_extent(&et->largest, &ri->i_ext);
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 289bcb7ca300..264b4e352319 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -192,14 +192,18 @@ void f2fs_abort_atomic_write(struct inode *inode, bool clean)
> > if (!f2fs_is_atomic_file(inode))
> > return;
> >
> > - if (clean)
> > - truncate_inode_pages_final(inode->i_mapping);
> > clear_inode_flag(fi->cow_inode, FI_COW_FILE);
> > iput(fi->cow_inode);
> > fi->cow_inode = NULL;
> > release_atomic_write_cnt(inode);
> > + clear_inode_flag(inode, FI_ATOMIC_COMMIT);
> > clear_inode_flag(inode, FI_ATOMIC_FILE);
> > stat_dec_atomic_inode(inode);
> > +
> > + if (clean) {
> > + truncate_inode_pages_final(inode->i_mapping);
> > + f2fs_i_size_write(inode, fi->original_i_size);
> > + }
> > }
> >
> > static int __replace_atomic_write_block(struct inode *inode, pgoff_t index,
> > @@ -335,10 +339,12 @@ static int __f2fs_commit_atomic_write(struct inode *inode)
> > }
> >
> > out:
> > - if (ret)
> > + if (ret) {
> > sbi->revoked_atomic_block += fi->atomic_write_cnt;
> > - else
> > + } else {
> > sbi->committed_atomic_block += fi->atomic_write_cnt;
> > + set_inode_flag(inode, FI_ATOMIC_COMMIT);
> > + }
> >
> > __complete_revoke_list(inode, &revoke_list, ret ? true : false);
> >
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