On Thu, Apr 06, 2023 at 06:50:22PM +0800, Shiyang Ruan wrote: > > > 在 2023/4/5 1:45, Darrick J. Wong 写道: > > On Tue, Mar 28, 2023 at 09:41:46AM +0000, 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() > > > `-> freeze_super() > > > `-> do xfs rmap > > > ` -> mf_dax_kill_procs() > > > ` -> collect_procs_fsdax() // all associated > > > ` -> unmap_and_kill() > > > ` -> invalidate_inode_pages2() // drop file's cache > > > `-> thaw_super() > > > > > > Introduce MF_MEM_PRE_REMOVE to let filesystem know this is a remove > > > event. Freeze the filesystem to prevent new dax mapping being created. > > > And 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. Also drop the cache of associated > > > files before pmem is removed. > > > > > > [1]: https://lore.kernel.org/linux-mm/161604050314.1463742.14151665140035795571.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > > > > > Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx> > > > --- > > > drivers/dax/super.c | 3 +- > > > fs/xfs/xfs_notify_failure.c | 56 +++++++++++++++++++++++++++++++++---- > > > include/linux/mm.h | 1 + > > > mm/memory-failure.c | 17 ++++++++--- > > > 4 files changed, 67 insertions(+), 10 deletions(-) > > > > > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > > > index c4c4728a36e4..2e1a35e82fce 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 1e2eddb8f90f..1b4eff43f9b5 100644 > > > --- a/fs/xfs/xfs_notify_failure.c > > > +++ b/fs/xfs/xfs_notify_failure.c > > > @@ -22,6 +22,7 @@ > > > #include <linux/mm.h> > > > #include <linux/dax.h> > > > +#include <linux/fs.h> > > > struct xfs_failure_info { > > > xfs_agblock_t startblock; > > > @@ -73,10 +74,16 @@ xfs_dax_failure_fn( > > > struct xfs_mount *mp = cur->bc_mp; > > > struct xfs_inode *ip; > > > struct xfs_failure_info *notify = data; > > > + struct address_space *mapping; > > > + pgoff_t pgoff; > > > + unsigned long pgcnt; > > > int error = 0; > > > if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) || > > > (rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) { > > > + /* The device is about to be removed. Not a really failure. */ > > > + if (notify->mf_flags & MF_MEM_PRE_REMOVE) > > > + return 0; > > > notify->want_shutdown = true; > > > return 0; > > > } > > > @@ -92,10 +99,18 @@ xfs_dax_failure_fn( > > > return 0; > > > } > > > - error = mf_dax_kill_procs(VFS_I(ip)->i_mapping, > > > - xfs_failure_pgoff(mp, rec, notify), > > > - xfs_failure_pgcnt(mp, rec, notify), > > > - notify->mf_flags); > > > + mapping = VFS_I(ip)->i_mapping; > > > + pgoff = xfs_failure_pgoff(mp, rec, notify); > > > + pgcnt = xfs_failure_pgcnt(mp, rec, notify); > > > + > > > + /* Continue the rmap query if the inode isn't a dax file. */ > > > + if (dax_mapping(mapping)) > > > + error = mf_dax_kill_procs(mapping, pgoff, pgcnt, > > > + notify->mf_flags); > > > + > > > + /* Invalidate the cache anyway. */ > > > + invalidate_inode_pages2_range(mapping, pgoff, pgoff + pgcnt - 1); > > > + > > > xfs_irele(ip); > > > return error; > > > } > > > @@ -164,11 +179,25 @@ xfs_dax_notify_ddev_failure( > > > } > > > xfs_trans_cancel(tp); > > > + > > > + /* Unfreeze filesystem anyway if it is freezed before. */ > > > + if (mf_flags & MF_MEM_PRE_REMOVE) { > > > + error = thaw_super(mp->m_super); > > > + if (error) > > > + return error; > > > > If someone *else* wanders in and thaws the fs, you'll get EINVAL here. > > > > I guess that's useful for knowing if someone's screwed up the freeze > > state on us, but ... really, don't you want to make sure you've gotten > > the freeze and nobody else can take it away? > > Ok, I know it now. > > > > I think you want the kernel-initiated freeze proposed by Luis here: > > https://lore.kernel.org/linux-fsdevel/20230114003409.1168311-4-mcgrof@xxxxxxxxxx/ > > This patch gives userspace higher priority to do freeze/thaw then > kernelspace. Userspace can thaw it even when kernelspace needs the freeze > state. But I think it can't happen in this case. Kernelspace(in this case) > should hold the freeze state and, IOW, has higher priority than userspace. > I think we could change the @usercall to @priority. > > -int freeze_super(struct super_block *sb) > +int freeze_super(struct super_block *sb, int priority) > > And priority definitions like: > #define FREEZE_PRO_AUTO 0 // for auto freeze What is an auto-freeze, and who would be calling it? I suspect we could get by with "exclusive" and "non-exclusive". Non-exclusive is the free-for-all we have now where any userspace can thaw, and exclusive is for kernel users (like PRE_REMOVE) who want to block everyone else from thawing. > #define FREEZE_PRO_USERCALL 1 // for user call > #define FREEZE_PRO_KERNELCALL 2 // for kernel call "Linux 6.5, now with FREEZE PRO!!!!" ;) THAW_PROT_* since we're really protecting who gets to thaw the fs; and "PROT" is a more customary mnemonic for 'protection. --D > > > -- > Thanks, > Ruan. > > > > > Also: Is Fujitsu still pursuing pmem products? Even though Optane is > > dead? I'm no longer sure of what the roadmap is for all this fsdax code > > and whatnot. > > > > --D > > > > > + } > > > + > > > + /* > > > + * Determine how to shutdown the filesystem according to the > > > + * error code and flags. > > > + */ > > > if (error || notify.want_shutdown) { > > > xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_ONDISK); > > > if (!error) > > > error = -EFSCORRUPTED; > > > - } > > > + } else if (mf_flags & MF_MEM_PRE_REMOVE) > > > + xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT); > > > + > > > return error; > > > } > > > @@ -182,6 +211,7 @@ xfs_dax_notify_failure( > > > struct xfs_mount *mp = dax_holder(dax_dev); > > > u64 ddev_start; > > > u64 ddev_end; > > > + int error; > > > if (!(mp->m_super->s_flags & SB_BORN)) { > > > xfs_warn(mp, "filesystem is not ready for notify_failure()!"); > > > @@ -196,6 +226,8 @@ 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; > > > @@ -209,6 +241,12 @@ xfs_dax_notify_failure( > > > ddev_start = mp->m_ddev_targp->bt_dax_part_off; > > > ddev_end = ddev_start + bdev_nr_bytes(mp->m_ddev_targp->bt_bdev) - 1; > > > + /* Notify failure on the whole device. */ > > > + if (offset == 0 && len == U64_MAX) { > > > + offset = ddev_start; > > > + len = bdev_nr_bytes(mp->m_ddev_targp->bt_bdev); > > > + } > > > + > > > /* Ignore the range out of filesystem area */ > > > if (offset + len - 1 < ddev_start) > > > return -ENXIO; > > > @@ -225,6 +263,14 @@ xfs_dax_notify_failure( > > > if (offset + len - 1 > ddev_end) > > > len = ddev_end - offset + 1; > > > + if (mf_flags & MF_MEM_PRE_REMOVE) { > > > + xfs_info(mp, "device is about to be removed!"); > > > + /* Freeze the filesystem to prevent new mappings created. */ > > > + error = freeze_super(mp->m_super); > > > + if (error) > > > + return error; > > > + } > > > + > > > return xfs_dax_notify_ddev_failure(mp, BTOBB(offset), BTOBB(len), > > > mf_flags); > > > } > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > > index 1f79667824eb..ac3f22c20e1d 100644 > > > --- a/include/linux/mm.h > > > +++ b/include/linux/mm.h > > > @@ -3436,6 +3436,7 @@ 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); > > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > > > index fae9baf3be16..6e6acec45568 100644 > > > --- a/mm/memory-failure.c > > > +++ b/mm/memory-failure.c > > > @@ -623,7 +623,7 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill, > > > */ > > > static void collect_procs_fsdax(struct page *page, > > > struct address_space *mapping, pgoff_t pgoff, > > > - struct list_head *to_kill) > > > + struct list_head *to_kill, bool pre_remove) > > > { > > > struct vm_area_struct *vma; > > > struct task_struct *tsk; > > > @@ -631,8 +631,15 @@ static void collect_procs_fsdax(struct page *page, > > > i_mmap_lock_read(mapping); > > > read_lock(&tasklist_lock); > > > for_each_process(tsk) { > > > - struct task_struct *t = task_early_kill(tsk, true); > > > + struct task_struct *t = tsk; > > > + /* > > > + * Search for all tasks while MF_MEM_PRE_REMOVE, because the > > > + * current may not be the one accessing the fsdax page. > > > + * Otherwise, search for the current task. > > > + */ > > > + if (!pre_remove) > > > + t = task_early_kill(tsk, true); > > > if (!t) > > > continue; > > > vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { > > > @@ -1732,6 +1739,7 @@ int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, > > > dax_entry_t cookie; > > > struct page *page; > > > size_t end = index + count; > > > + bool pre_remove = mf_flags & MF_MEM_PRE_REMOVE; > > > mf_flags |= MF_ACTION_REQUIRED | MF_MUST_KILL; > > > @@ -1743,9 +1751,10 @@ int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, > > > if (!page) > > > goto unlock; > > > - SetPageHWPoison(page); > > > + if (!pre_remove) > > > + SetPageHWPoison(page); > > > - collect_procs_fsdax(page, mapping, index, &to_kill); > > > + collect_procs_fsdax(page, mapping, index, &to_kill, pre_remove); > > > unmap_and_kill(&to_kill, page_to_pfn(page), mapping, > > > index, mf_flags); > > > unlock: > > > -- > > > 2.39.2 > > >
