Messages in this thread | | | Date | Wed, 6 Jan 2021 14:57:15 -0800 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH v2] f2fs: fix to keep isolation of atomic write |
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On 01/06, Jaegeuk Kim wrote: > Hi Chao, > > With a quick test, this patch causes down_write failure resulting in blocking > process. I didn't dig in the bug so, please check the code again. :P
nvm. I can see it works now.
> > 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 > > - 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 > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
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