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Date: Mon, 29 Aug 2022 18:02:11 +0800
From: Shiyang Ruan <ruansy.fnst@...itsu.com>
To: Dan Williams <dan.j.williams@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
"nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
CC: "djwong@...nel.org" <djwong@...nel.org>,
"david@...morbit.com" <david@...morbit.com>,
"hch@...radead.org" <hch@...radead.org>,
"jane.chu@...cle.com" <jane.chu@...cle.com>
Subject: Re: [PATCH v7] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind
在 2022/8/27 5:35, Dan Williams 写道:
> Shiyang Ruan wrote:
>> This patch is inspired by Dan's "mm, dax, pmem: Introduce
>> dev_pagemap_failure()"[1]. With the help of dax_holder and
>> ->notify_failure() mechanism, the pmem driver is able to ask filesystem
>> (or mapped device) on it to unmap all files in use and notify processes
>> who are using those files.
>>
>> Call trace:
>> trigger unbind
>> -> unbind_store()
>> -> ... (skip)
>> -> devres_release_all()
>> -> kill_dax()
>> -> dax_holder_notify_failure(dax_dev, 0, U64_MAX, MF_MEM_PRE_REMOVE)
>> -> xfs_dax_notify_failure()
>>
>> Introduce MF_MEM_PRE_REMOVE to let filesystem know this is a remove
>> event. So do not shutdown filesystem directly if something not
>> supported, or if failure range includes metadata area. Make sure all
>> files and processes are handled correctly.
>>
>> ==
>> Changes since v6:
>> 1. Rebase on 6.0-rc2 and Darrick's patch[2].
>>
>> Changes since v5:
>> 1. Renamed MF_MEM_REMOVE to MF_MEM_PRE_REMOVE
>> 2. hold s_umount before sync_filesystem()
>> 3. do sync_filesystem() after SB_BORN check
>> 4. Rebased on next-20220714
>>
>> [1]:
>> https://lore.kernel.org/linux-mm/161604050314.1463742.14151665140035795571.stgit@dwillia2-desk3.amr.corp.intel.com/
>> [2]: https://lore.kernel.org/linux-xfs/Yv5wIa2crHioYeRr@magnolia/
>>
>> Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>
>> Reviewed-by: Darrick J. Wong <djwong@...nel.org>
>> ---
>> drivers/dax/super.c | 3 ++-
>> fs/xfs/xfs_notify_failure.c | 15 +++++++++++++++
>> include/linux/mm.h | 1 +
>> 3 files changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
>> index 9b5e2a5eb0ae..cf9a64563fbe 100644
>> --- a/drivers/dax/super.c
>> +++ b/drivers/dax/super.c
>> @@ -323,7 +323,8 @@ void kill_dax(struct dax_device *dax_dev)
>> return;
>> if (dax_dev->holder_data != NULL)
>> - dax_holder_notify_failure(dax_dev, 0, U64_MAX, 0);
>> + dax_holder_notify_failure(dax_dev, 0, U64_MAX,
>> + MF_MEM_PRE_REMOVE);
>> clear_bit(DAXDEV_ALIVE, &dax_dev->flags);
>> synchronize_srcu(&dax_srcu);
>> diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c
>> index 65d5eb20878e..a9769f17e998 100644
>> --- a/fs/xfs/xfs_notify_failure.c
>> +++ b/fs/xfs/xfs_notify_failure.c
>> @@ -77,6 +77,9 @@ xfs_dax_failure_fn(
>> if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) ||
>> (rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) {
>> + /* Do not shutdown so early when device is to be removed */
>> + if (notify->mf_flags & MF_MEM_PRE_REMOVE)
>> + return 0;
>> notify->want_shutdown = true;
>> return 0;
>> }
>> @@ -182,12 +185,22 @@ xfs_dax_notify_failure(
>> struct xfs_mount *mp = dax_holder(dax_dev);
>> u64 ddev_start;
>> u64 ddev_end;
>> + int error;
>> if (!(mp->m_sb.sb_flags & SB_BORN)) {
>
> How are you testing the SB_BORN interactions? I have a fix for this
> pending here:
>
> https://lore.kernel.org/nvdimm/166153428094.2758201.7936572520826540019.stgit@dwillia2-xfh.jf.intel.com/
That was my mistake. Yes, it should be mp->m_super->s_flags.
(I remember my testcase did pass in my dev version, but now that seems
impossible. I think something was wrong when I did the test.)
>
>> xfs_warn(mp, "filesystem is not ready for notify_failure()!");
>> return -EIO;
>> }
>> + if (mf_flags & MF_MEM_PRE_REMOVE) {
>
> It appears this patch is corrupted here. I confirmed that b4 sees the
> same when trying to apply it.
Can't this patch be applied? It is based on 6.0-rc2 + Darrick's patch.
It's also ok to rebase on 6.0-rc3 + Darrick's patch.
>
>> + xfs_info(mp, "device is about to be removed!");
>> + down_write(&mp->m_super->s_umount);
>> + error = sync_filesystem(mp->m_super);
>
> This syncs to make data persistent, but for DAX this also needs to get
> invalidate all current DAX mappings. I do not see that in these changes.
I'll add it.
--
Thanks,
Ruan.
>
>> + up_write(&mp->m_super->s_umount);
>> + if (error)
>> + return error;
>> + }
>> +
>> if (mp->m_rtdev_targp && mp->m_rtdev_targp->bt_daxdev == dax_dev) {
>> xfs_warn(mp,
>> "notify_failure() not supported on realtime device!");
>> @@ -196,6 +209,8 @@ xfs_dax_notify_failure(
>> if (mp->m_logdev_targp && mp->m_logdev_targp->bt_daxdev == dax_dev &&
>> mp->m_logdev_targp != mp->m_ddev_targp) {
>> + if (mf_flags & MF_MEM_PRE_REMOVE)
>> + return 0;
>> xfs_err(mp, "ondisk log corrupt, shutting down fs!");
>> xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_ONDISK);
>> return -EFSCORRUPTED;
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index 982f2607180b..2c7c132e6512 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -3176,6 +3176,7 @@ enum mf_flags {
>> MF_UNPOISON = 1 << 4,
>> MF_SW_SIMULATED = 1 << 5,
>> MF_NO_RETRY = 1 << 6,
>> + MF_MEM_PRE_REMOVE = 1 << 7,
>> };
>> int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index,
>> unsigned long count, int mf_flags);
>> --
>> 2.37.2
>>
>>
>
>
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