Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2] f2fs: fix to keep isolation of atomic write | From | Chao Yu <> | Date | Fri, 15 Jan 2021 15:59:03 +0800 |
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On 2021/1/15 5:53, Jaegeuk Kim wrote: > On 12/30, Chao Yu wrote: >> ThreadA ThreadB >> - f2fs_ioc_start_atomic_write >> - write >> - f2fs_ioc_commit_atomic_write >> - f2fs_commit_inmem_pages >> - f2fs_drop_inmem_pages >> - f2fs_drop_inmem_pages >> - __revoke_inmem_pages >> - f2fs_vm_page_mkwrite >> - set_page_dirty >> - tag ATOMIC_WRITTEN_PAGE and add page >> to inmem_pages list >> - clear_inode_flag(FI_ATOMIC_FILE) >> - f2fs_vm_page_mkwrite >> - set_page_dirty >> - f2fs_update_dirty_page >> - f2fs_trace_pid >> - tag inmem page private to pid > > Hmm, how about removing fs/f2fs/trace.c to make private more complicated > like this? I think we can get IO traces from tracepoints.
Hmm, actually, there is are issues, one is the trace IO, the other is the race issue (atomic_start,commit,drop vs mkwrite) which can make isolation semantics of transaction be broken.
Or can we avoid atomic file racing with file mmap?
- atomic_start - file_mmap - inode_lock - if (FI_ATOMIC_FILE) return - inode_lock - if (FI_MMAP_FILE) return
Thanks,
> >> - truncate >> - f2fs_invalidate_page >> - set page->mapping to NULL >> then it will cause panic once we >> access page->mapping >> >> The root cause is we missed to keep isolation of atomic write in the case >> of commit_atomic_write vs mkwrite, let commit_atomic_write helds i_mmap_sem >> lock to avoid this issue. >> >> Signed-off-by: Chao Yu <yuchao0@huawei.com> >> --- >> v2: >> - use i_mmap_sem to avoid mkwrite racing with below flows: >> * f2fs_ioc_start_atomic_write >> * f2fs_drop_inmem_pages >> * f2fs_commit_inmem_pages >> >> fs/f2fs/file.c | 3 +++ >> fs/f2fs/segment.c | 7 +++++++ >> 2 files changed, 10 insertions(+) >> >> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >> index 4e6d4b9120a8..a48ec650d691 100644 >> --- a/fs/f2fs/file.c >> +++ b/fs/f2fs/file.c >> @@ -2050,6 +2050,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) >> goto out; >> >> down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> + down_write(&F2FS_I(inode)->i_mmap_sem); >> >> /* >> * Should wait end_io to count F2FS_WB_CP_DATA correctly by >> @@ -2060,6 +2061,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) >> inode->i_ino, get_dirty_pages(inode)); >> ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX); >> if (ret) { >> + up_write(&F2FS_I(inode)->i_mmap_sem); >> up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> goto out; >> } >> @@ -2073,6 +2075,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) >> /* add inode in inmem_list first and set atomic_file */ >> set_inode_flag(inode, FI_ATOMIC_FILE); >> clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); >> + up_write(&F2FS_I(inode)->i_mmap_sem); >> up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); >> >> f2fs_update_time(F2FS_I_SB(inode), REQ_TIME); >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> index d8570b0359f5..dab870d9faf6 100644 >> --- a/fs/f2fs/segment.c >> +++ b/fs/f2fs/segment.c >> @@ -327,6 +327,8 @@ void f2fs_drop_inmem_pages(struct inode *inode) >> struct f2fs_sb_info *sbi = F2FS_I_SB(inode); >> struct f2fs_inode_info *fi = F2FS_I(inode); >> >> + down_write(&F2FS_I(inode)->i_mmap_sem); >> + >> while (!list_empty(&fi->inmem_pages)) { >> mutex_lock(&fi->inmem_lock); >> __revoke_inmem_pages(inode, &fi->inmem_pages, >> @@ -344,6 +346,8 @@ void f2fs_drop_inmem_pages(struct inode *inode) >> sbi->atomic_files--; >> } >> spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); >> + >> + up_write(&F2FS_I(inode)->i_mmap_sem); >> } >> >> void f2fs_drop_inmem_page(struct inode *inode, struct page *page) >> @@ -467,6 +471,7 @@ int f2fs_commit_inmem_pages(struct inode *inode) >> f2fs_balance_fs(sbi, true); >> >> down_write(&fi->i_gc_rwsem[WRITE]); >> + down_write(&F2FS_I(inode)->i_mmap_sem); >> >> f2fs_lock_op(sbi); >> set_inode_flag(inode, FI_ATOMIC_COMMIT); >> @@ -478,6 +483,8 @@ int f2fs_commit_inmem_pages(struct inode *inode) >> clear_inode_flag(inode, FI_ATOMIC_COMMIT); >> >> f2fs_unlock_op(sbi); >> + >> + up_write(&F2FS_I(inode)->i_mmap_sem); >> up_write(&fi->i_gc_rwsem[WRITE]); >> >> return err; >> -- >> 2.29.2 > . >
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