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From: Zhihao Cheng <chengzhihao1@huawei.com>
To: Richard Weinberger <richard@nod.at>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	mcoquelin stm32 <mcoquelin.stm32@gmail.com>,
	"kirill shutemov" <kirill.shutemov@linux.intel.com>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 05/15] ubifs: Rename whiteout atomically
Date: Mon, 10 Jan 2022 17:35:02 +0800	[thread overview]
Message-ID: <0477fadd-dfb5-c581-ee6a-ed6df9a966a3@huawei.com> (raw)
In-Reply-To: <1985807262.244880.1641762859448.JavaMail.zimbra@nod.at>

Hi, Richard
> 
> How do you make sure the the whiteout is never written to disk (by writeback) before ubifs_jnl_rename() linked
> it? That's the reason why other filesystems use the tmpfile mechanism for whiteouts too.
> 

The whiteout inode is clean after creation from create_whiteout(), and 
it can't be marked dirty until ubifs_jnl_rename() finished. So, I think 
there is no chance for whiteout being written on disk. Then, 
'ubifs_assert(c, !whiteout_ui->dirty)' never fails in ubifs_jnl_rename() 
during my local stress tests. You may add some delay executions after 
whiteout creation to make sure that whiteout won't be written back 
before ubifs_jnl_rename().

BTW, I considered plan B(Binding whiteout to a negative dentry), but we 
cannot get parent dir's entry in do_rename(), so I abandoned it.
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1334,7 +1335,8 @@ static int do_rename(struct inode *old_dir, struct 
dentry *old_dentry,
                         goto out_release;
                 }

-               err = do_tmpfile(old_dir, old_dentry, S_IFCHR | 
WHITEOUT_MODE, &whiteout);
+               // tmp_dentry = d_alloc(old_dir_dentry, &slash_name); 
// refer to vfs_tmpfile
+               err = do_tmpfile(old_dir, tmp_dentry, S_IFCHR | 
WHITEOUT_MODE, &whiteout);
                 if (err) {
                         kfree(dev);
                         goto out_release;

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  reply	other threads:[~2022-01-10  9:40 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-27  3:22 [PATCH v6 00/15] Some bugfixs for ubi/ubifs Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 01/15] ubifs: rename_whiteout: Fix double free for whiteout_ui->data Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 02/15] ubifs: Fix deadlock in concurrent rename whiteout and inode writeback Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 03/15] ubifs: Fix wrong number of inodes locked by ui_mutex in ubifs_inode comment Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 04/15] ubifs: Add missing iput if do_tmpfile() failed in rename whiteout Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 05/15] ubifs: Rename whiteout atomically Zhihao Cheng
2022-01-09 21:14   ` Richard Weinberger
2022-01-10  9:35     ` Zhihao Cheng [this message]
2022-01-10 10:14       ` Richard Weinberger
2022-01-10 20:58         ` Richard Weinberger
2021-12-27  3:22 ` [PATCH v6 06/15] ubifs: Fix 'ui->dirty' race between do_tmpfile() and writeback work Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 07/15] ubifs: Rectify space amount budget for mkdir/tmpfile operations Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 08/15] ubifs: setflags: Make dirtied_ino_d 8 bytes aligned Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 09/15] ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock() Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 10/15] ubifs: Fix to add refcount once page is set private Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 11/15] ubi: fastmap: Return error code if memory allocation fails in add_aeb() Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 12/15] ubi: fastmap: Add all fastmap pebs into 'ai->fastmap' when fm->used_blocks>=2 Zhihao Cheng
2022-01-10 23:23   ` Richard Weinberger
2022-01-11  2:48     ` Zhihao Cheng
2022-01-11  7:27       ` Richard Weinberger
2022-01-11 11:44         ` Zhihao Cheng
2022-01-11 11:57           ` Richard Weinberger
2022-01-11 13:23             ` Zhihao Cheng
2022-01-11 13:56               ` Richard Weinberger
2022-01-12  3:46                 ` Zhihao Cheng
2022-01-14 18:45                   ` Richard Weinberger
2022-01-15  8:22                     ` Zhihao Cheng
2022-01-15  8:46                       ` Zhihao Cheng
2022-01-15 10:01                         ` Richard Weinberger
2022-01-17  1:31                           ` Zhihao Cheng
2022-01-17  2:52                             ` Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 13/15] ubifs: ubifs_writepage: Mark page dirty after writing inode failed Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 14/15] ubifs: ubifs_releasepage: Remove ubifs_assert(0) to valid this process Zhihao Cheng
2021-12-27  3:22 ` [PATCH v6 15/15] ubi: fastmap: Fix high cpu usage of ubi_bgt by making sure wl_pool not empty Zhihao Cheng
2022-01-17  1:40   ` Zhihao Cheng
2021-12-27 10:13 ` [PATCH v6 00/15] Some bugfixs for ubi/ubifs Richard Weinberger
2021-12-27 12:19   ` Zhihao Cheng
2021-12-27 13:00     ` Richard Weinberger

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