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.
> - 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 <yuch...@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
