This makes xfstests/083 stuck. So, I'll drop it for a while.
On 09/26, Chao Yu wrote:
> From: Chao Yu <yuch...@huawei.com>
>
> Thread A Thread B
> - f2fs_vm_page_mkwrite
> - f2fs_setattr
> - down_write(i_mmap_sem)
> - truncate_setsize
> - f2fs_truncate
> - up_write(i_mmap_sem)
> - f2fs_reserve_block
> reserve NEW_ADDR
> - skip dirty page due to truncation
>
> 1. we don't need to rserve new block address for a truncated page.
> 2. dn.data_blkaddr is used out of node page lock coverage.
>
> Refactor ->page_mkwrite() flow to fix above issues:
> - use __do_map_lock() to avoid racing checkpoint()
> - lock data page in prior to dnode page
> - cover f2fs_reserve_block with i_mmap_sem lock
> - access dn.data_blkaddr under dnode lock
>
> Signed-off-by: Chao Yu <yuch...@huawei.com>
> ---
> fs/f2fs/file.c | 29 ++++++++++++++---------------
> 1 file changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 6f02c8daff76..fcb4788b48aa 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -47,7 +47,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
> struct page *page = vmf->page;
> struct inode *inode = file_inode(vmf->vma->vm_file);
> struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> - struct dnode_of_data dn;
> + struct dnode_of_data dn = { .node_changed = false };
> int err;
>
> if (unlikely(f2fs_cp_error(sbi))) {
> @@ -59,19 +59,6 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault
> *vmf)
>
> f2fs_bug_on(sbi, f2fs_has_inline_data(inode));
>
> - /* block allocation */
> - f2fs_lock_op(sbi);
> - set_new_dnode(&dn, inode, NULL, NULL, 0);
> - err = f2fs_reserve_block(&dn, page->index);
> - if (err) {
> - f2fs_unlock_op(sbi);
> - goto out;
> - }
> - f2fs_put_dnode(&dn);
> - f2fs_unlock_op(sbi);
> -
> - f2fs_balance_fs(sbi, dn.node_changed);
> -
> file_update_time(vmf->vma->vm_file);
> down_read(&F2FS_I(inode)->i_mmap_sem);
> lock_page(page);
> @@ -108,12 +95,24 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault
> *vmf)
> /* fill the page */
> f2fs_wait_on_page_writeback(page, DATA, false);
>
> + /* block allocation */
> + __do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, true);
> + set_new_dnode(&dn, inode, NULL, NULL, 0);
> + err = f2fs_reserve_block(&dn, page->index);
> + if (err)
> + goto out_unlock;
> +
> /* wait for GCed page writeback via META_MAPPING */
> f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);
>
> + f2fs_put_dnode(&dn);
> +out_unlock:
> + __do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, false);
> out_sem:
> up_read(&F2FS_I(inode)->i_mmap_sem);
> -out:
> +
> + f2fs_balance_fs(sbi, dn.node_changed);
> +
> sb_end_pagefault(inode->i_sb);
> f2fs_update_time(sbi, REQ_TIME);
> err:
> --
> 2.18.0
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