Messages in this thread | | | Date | Fri, 24 Jun 2022 09:51:15 +0800 | Subject | Re: [RFC PATCH v3] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind | From | Shiyang Ruan <> |
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在 2022/6/23 0:49, Darrick J. Wong 写道: > On Wed, Jun 15, 2022 at 08:54:00PM +0800, 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() # was pmem driver ->remove() in v1 >> -> kill_dax() >> -> dax_holder_notify_failure(dax_dev, 0, U64_MAX, MF_MEM_REMOVE) >> -> xfs_dax_notify_failure() >> >> Introduce MF_MEM_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. >> >> [1]: https://lore.kernel.org/linux-mm/161604050314.1463742.14151665140035795571.stgit@dwillia2-desk3.amr.corp.intel.com/ >> >> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> >> >> == >> Changes since v2: >> 1. Rebased on next-20220615 >> >> Changes since v1: >> 1. Drop the needless change of moving {kill,put}_dax() >> 2. Rebased on '[PATCHSETS] v14 fsdax-rmap + v11 fsdax-reflink'[2] >> >> --- >> drivers/dax/super.c | 2 +- >> fs/xfs/xfs_notify_failure.c | 6 +++++- >> include/linux/mm.h | 1 + >> 3 files changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/dax/super.c b/drivers/dax/super.c >> index 9b5e2a5eb0ae..d4bc83159d46 100644 >> --- a/drivers/dax/super.c >> +++ b/drivers/dax/super.c >> @@ -323,7 +323,7 @@ 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_REMOVE); > > At the point we're initiating a MEM_REMOVE call, is the pmem already > gone, or is it about to be gone?
It's about to be gone.
I found two cases: 1. exec `unbind` by user, who wants to unplug the pmem 2. handle failures during initialization
> >> >> 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 aa8dc27c599c..91d3f05d4241 100644 >> --- a/fs/xfs/xfs_notify_failure.c >> +++ b/fs/xfs/xfs_notify_failure.c >> @@ -73,7 +73,9 @@ xfs_dax_failure_fn( >> struct failure_info *notify = data; >> int error = 0; >> >> - if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) || >> + /* Do not shutdown so early when device is to be removed */ >> + if (!(notify->mf_flags & MF_MEM_REMOVE) || >> + XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) || >> (rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) { >> xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_ONDISK); >> return -EFSCORRUPTED; >> @@ -182,6 +184,8 @@ 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_REMOVE) >> + return -EOPNOTSUPP; > > The reason I ask is that if the pmem is *about to be* but not yet > removed from the system, shouldn't we at least try to flush all dirty > files and the log to reduce data loss and minimize recovery time?
Yes, they should be flushed. Will add it.
-- Thanks, Ruan.
> > If it's already gone, then you might as well shut down immediately, > unless there's a chance the pmem will come back(?) > > --D > >> 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 623c2ee8330a..bbeb31883362 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -3249,6 +3249,7 @@ enum mf_flags { >> MF_SOFT_OFFLINE = 1 << 3, >> MF_UNPOISON = 1 << 4, >> MF_NO_RETRY = 1 << 5, >> + MF_MEM_REMOVE = 1 << 6, >> }; >> int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, >> unsigned long count, int mf_flags); >> -- >> 2.36.1 >> >> >>
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