On 2018/4/26 23:48, Jaegeuk Kim wrote: > On 04/26, Chao Yu wrote: >> Thread A Thread B >> - f2fs_ioc_commit_atomic_write >> - commit_inmem_pages >> - f2fs_submit_merged_write_cond >> : write data >> - write_checkpoint >> - do_checkpoint >> : commit all node within CP >> -> SPO >> - f2fs_do_sync_file >> - file_write_and_wait_range >> : wait data writeback >> >> In above race condition, data/node can be flushed in reversed order when >> coming a checkpoint before f2fs_do_sync_file, after SPOR, it results in >> atomic written data being corrupted. > > Wait, what is the problem here? Thread B could succeed checkpoint, there is > no problem. If it fails, there is no fsync mark where we can recover it, so
Node is flushed by checkpoint before data, with reversed order, that's the problem. Thanks, > we can just ignore the last written data as nothing. > >> >> This patch adds f2fs_wait_on_page_writeback in __revoke_inmem_pages() to >> keep data and node of atomic file being flushed orderly. >> >> Signed-off-by: Chao Yu <yuch...@huawei.com> >> --- >> fs/f2fs/file.c | 4 ++++ >> fs/f2fs/segment.c | 3 +++ >> 2 files changed, 7 insertions(+) >> >> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >> index be7578774a47..a352804af244 100644 >> --- a/fs/f2fs/file.c >> +++ b/fs/f2fs/file.c >> @@ -217,6 +217,9 @@ static int f2fs_do_sync_file(struct file *file, loff_t >> start, loff_t end, >> >> trace_f2fs_sync_file_enter(inode); >> >> + if (atomic) >> + goto write_done; >> + >> /* if fdatasync is triggered, let's do in-place-update */ >> if (datasync || get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks) >> set_inode_flag(inode, FI_NEED_IPU); >> @@ -228,6 +231,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t >> start, loff_t end, >> return ret; >> } >> >> +write_done: >> /* if the inode is dirty, let's recover all the time */ >> if (!f2fs_skip_inode_update(inode, datasync)) { >> f2fs_write_inode(inode, NULL); >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> index 584483426584..9ca3d0a43d93 100644 >> --- a/fs/f2fs/segment.c >> +++ b/fs/f2fs/segment.c >> @@ -230,6 +230,8 @@ static int __revoke_inmem_pages(struct inode *inode, >> >> lock_page(page); >> >> + f2fs_wait_on_page_writeback(page, DATA, true); >> + >> if (recover) { >> struct dnode_of_data dn; >> struct node_info ni; >> @@ -415,6 +417,7 @@ static int __commit_inmem_pages(struct inode *inode) >> /* drop all uncommitted pages */ >> __revoke_inmem_pages(inode, &fi->inmem_pages, true, false); >> } else { >> + /* wait all committed IOs writeback and release them from list >> */ >> __revoke_inmem_pages(inode, &revoke_list, false, false); >> } >> >> -- >> 2.15.0.55.gc2ece9dc4de6 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel