Messages in this thread | | | Subject | Re: [PATCH 1/2] f2fs: enable to gc page whose inode already atomic commit | From | Yunlong Song <> | Date | Mon, 5 Feb 2018 17:37:40 +0800 |
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> OK, details as I explained before: > > atomic_commit GC > - file_write_and_wait_range > - move_data_block > - f2fs_submit_page_write > - f2fs_update_data_blkaddr > - set_page_dirty > - fsync_node_pages > > 1. atomic writes data page #1 & update node #1 > 2. GC data page #2 & update node #2 > 3. page #1 & node #1 & #2 can be committed into nand flash before page #2 be > committed. > > After a sudden pow-cut, database transaction will be inconsistent. So I think > there will be better to exclude gc/atomic_write to each other, with a lock > instead of flag checking. >
I do not understand why this transaction is inconsistent, is it a problem that page #2 is not committed into nand flash? Since normal gc also has this problem:
Suppose that there is db file A, f2fs_gc moves data page #1 of db file A. But if write checkpoint only commit node page #1 and then a sudden power-cut happens. Data page #1 is not committed to nand flash, but node page #1 is committed. Is the db transaction broken and inconsistent?
Come back to your example, I think data page 2 of atomic file does not belong to this transaction, so even node page 2 is committed, it is just the same problem as what I have listed above(db file A), and it does not break this transaction.
> Thanks, > >>>>> >>>>> So how about just using dio_rwsem[WRITE] during atomic committing to exclude >>>>> GCing data block of atomic opened file? >>>>> >>>>> Thanks, >>>>> >>>>>> >>>>>> Signed-off-by: Yunlong Song <yunlong.song@huawei.com> >>>>>> --- >>>>>> fs/f2fs/data.c | 5 ++--- >>>>>> fs/f2fs/gc.c | 6 ++++-- >>>>>> 2 files changed, 6 insertions(+), 5 deletions(-) >>>>>> >>>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >>>>>> index 7435830..edafcb6 100644 >>>>>> --- a/fs/f2fs/data.c >>>>>> +++ b/fs/f2fs/data.c >>>>>> @@ -1580,14 +1580,13 @@ bool should_update_outplace(struct inode *inode, struct f2fs_io_info *fio) >>>>>> return true; >>>>>> if (S_ISDIR(inode->i_mode)) >>>>>> return true; >>>>>> - if (f2fs_is_atomic_file(inode)) >>>>>> - return true; >>>>>> if (fio) { >>>>>> if (is_cold_data(fio->page)) >>>>>> return true; >>>>>> if (IS_ATOMIC_WRITTEN_PAGE(fio->page)) >>>>>> return true; >>>>>> - } >>>>>> + } else if (f2fs_is_atomic_file(inode)) >>>>>> + return true; >>>>>> return false; >>>>>> } >>>>>> >>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>>>>> index b9d93fd..84ab3ff 100644 >>>>>> --- a/fs/f2fs/gc.c >>>>>> +++ b/fs/f2fs/gc.c >>>>>> @@ -622,7 +622,8 @@ static void move_data_block(struct inode *inode, block_t bidx, >>>>>> if (!check_valid_map(F2FS_I_SB(inode), segno, off)) >>>>>> goto out; >>>>>> >>>>>> - if (f2fs_is_atomic_file(inode)) >>>>>> + if (f2fs_is_atomic_file(inode) && >>>>>> + !f2fs_is_commit_atomic_write(inode)) >>>>>> goto out; >>>>>> >>>>>> if (f2fs_is_pinned_file(inode)) { >>>>>> @@ -729,7 +730,8 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type, >>>>>> if (!check_valid_map(F2FS_I_SB(inode), segno, off)) >>>>>> goto out; >>>>>> >>>>>> - if (f2fs_is_atomic_file(inode)) >>>>>> + if (f2fs_is_atomic_file(inode) && >>>>>> + !f2fs_is_commit_atomic_write(inode)) >>>>>> goto out; >>>>>> if (f2fs_is_pinned_file(inode)) { >>>>>> if (gc_type == FG_GC) >>>>>> >>>>> >>>>> . >>>>> >>>> >>> >>> >>> . >>> >> > > > . >
-- Thanks, Yunlong Song
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