[PATCH v9 0/3] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind

[PATCH v9 0/3] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind

[Shiyang Ruan]

Changes since v8:
  1. P2: rename drop_pagecache_sb() to super_drop_pagecache().
  2. P2: let super_drop_pagecache() accept invalidate method.
  3. P3: invalidate all dax mappings by invalidate_inode_pages2().
  4. P3: shutdown the filesystem when it is to be removed.
  5. Rebase on 6.0-rc6 + Darrick's patch[1] + Dan's patch[2].

[1]: https://lore.kernel.org/linux-xfs/Yv5wIa2crHioYeRr@magnolia/
[2]: https://lore.kernel.org/linux-xfs/166153426798.2758201.15108211981034512993.stgit@dwillia2-xfh.jf.intel.com/

Shiyang Ruan (3):
  xfs: fix the calculation of length and end
  fs: move drop_pagecache_sb() for others to use
  mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind

 drivers/dax/super.c         |  3 ++-
 fs/drop_caches.c            | 35 ++----------------------------
 fs/super.c                  | 43 +++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_notify_failure.c | 36 ++++++++++++++++++++++++++-----
 include/linux/fs.h          |  1 +
 include/linux/mm.h          |  1 +
 include/linux/pagemap.h     |  1 +
 mm/truncate.c               | 20 +++++++++++++++--
 8 files changed, 99 insertions(+), 41 deletions(-)

-- 
2.37.3

[PATCH 1/3] xfs: fix the calculation of length and end

[Shiyang Ruan]

The end should be start + length - 1.  Also fix the calculation of the
length when seeking for intersection of notify range and device.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_notify_failure.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c
index c4078d0ec108..3830f908e215 100644
--- a/fs/xfs/xfs_notify_failure.c
+++ b/fs/xfs/xfs_notify_failure.c
@@ -114,7 +114,7 @@ xfs_dax_notify_ddev_failure(
 	int			error = 0;
 	xfs_fsblock_t		fsbno = XFS_DADDR_TO_FSB(mp, daddr);
 	xfs_agnumber_t		agno = XFS_FSB_TO_AGNO(mp, fsbno);
-	xfs_fsblock_t		end_fsbno = XFS_DADDR_TO_FSB(mp, daddr + bblen);
+	xfs_fsblock_t		end_fsbno = XFS_DADDR_TO_FSB(mp, daddr + bblen - 1);
 	xfs_agnumber_t		end_agno = XFS_FSB_TO_AGNO(mp, end_fsbno);
 
 	error = xfs_trans_alloc_empty(mp, &tp);
@@ -210,7 +210,7 @@ xfs_dax_notify_failure(
 	ddev_end = ddev_start + bdev_nr_bytes(mp->m_ddev_targp->bt_bdev) - 1;
 
 	/* Ignore the range out of filesystem area */
-	if (offset + len < ddev_start)
+	if (offset + len - 1 < ddev_start)
 		return -ENXIO;
 	if (offset > ddev_end)
 		return -ENXIO;
@@ -222,8 +222,8 @@ xfs_dax_notify_failure(
 		len -= ddev_start - offset;
 		offset = 0;
 	}
-	if (offset + len > ddev_end)
-		len -= ddev_end - offset;
+	if (offset + len - 1 > ddev_end)
+		len -= offset + len - 1 - ddev_end;
 
 	return xfs_dax_notify_ddev_failure(mp, BTOBB(offset), BTOBB(len),
 			mf_flags);
-- 
2.37.3

[PATCH 2/3] fs: move drop_pagecache_sb() for others to use

[Shiyang Ruan]

xfs_notify_failure.c requires a method to invalidate all dax mappings.
drop_pagecache_sb() can do this but it is a static function and only
build with CONFIG_SYSCTL.  Now, move it to super.c and make it available
for others.  And use its second argument to choose which invalidate
method to use.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
 fs/drop_caches.c        | 35 ++-------------------------------
 fs/super.c              | 43 +++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h      |  1 +
 include/linux/pagemap.h |  1 +
 mm/truncate.c           | 20 +++++++++++++++++--
 5 files changed, 65 insertions(+), 35 deletions(-)

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index e619c31b6bd9..4c9281885077 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -15,38 +15,6 @@
 /* A global variable is a bit ugly, but it keeps the code simple */
 int sysctl_drop_caches;
 
-static void drop_pagecache_sb(struct super_block *sb, void *unused)
-{
-	struct inode *inode, *toput_inode = NULL;
-
-	spin_lock(&sb->s_inode_list_lock);
-	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
-		spin_lock(&inode->i_lock);
-		/*
-		 * We must skip inodes in unusual state. We may also skip
-		 * inodes without pages but we deliberately won't in case
-		 * we need to reschedule to avoid softlockups.
-		 */
-		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
-		    (mapping_empty(inode->i_mapping) && !need_resched())) {
-			spin_unlock(&inode->i_lock);
-			continue;
-		}
-		__iget(inode);
-		spin_unlock(&inode->i_lock);
-		spin_unlock(&sb->s_inode_list_lock);
-
-		invalidate_mapping_pages(inode->i_mapping, 0, -1);
-		iput(toput_inode);
-		toput_inode = inode;
-
-		cond_resched();
-		spin_lock(&sb->s_inode_list_lock);
-	}
-	spin_unlock(&sb->s_inode_list_lock);
-	iput(toput_inode);
-}
-
 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
 		void *buffer, size_t *length, loff_t *ppos)
 {
@@ -59,7 +27,8 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int write,
 		static int stfu;
 
 		if (sysctl_drop_caches & 1) {
-			iterate_supers(drop_pagecache_sb, NULL);
+			iterate_supers(super_drop_pagecache,
+				       invalidate_inode_pages);
 			count_vm_event(DROP_PAGECACHE);
 		}
 		if (sysctl_drop_caches & 2) {
diff --git a/fs/super.c b/fs/super.c
index 734ed584a946..7cdbf146bc31 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -36,6 +36,7 @@
 #include <linux/lockdep.h>
 #include <linux/user_namespace.h>
 #include <linux/fs_context.h>
+#include <linux/pagemap.h>
 #include <uapi/linux/mount.h>
 #include "internal.h"
 
@@ -677,6 +678,48 @@ void drop_super_exclusive(struct super_block *sb)
 }
 EXPORT_SYMBOL(drop_super_exclusive);
 
+/*
+ *	super_drop_pagecache - drop all page caches of a filesystem
+ *	@sb: superblock to invalidate
+ *	@arg: invalidate method, such as invalidate_inode_pages(),
+ *	        invalidate_inode_pages2()
+ *
+ *	Scans the inodes of a filesystem, drop all page caches.
+ */
+void super_drop_pagecache(struct super_block *sb, void *arg)
+{
+	struct inode *inode, *toput_inode = NULL;
+	int (*invalidator)(struct address_space *) = arg;
+
+	spin_lock(&sb->s_inode_list_lock);
+	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+		spin_lock(&inode->i_lock);
+		/*
+		 * We must skip inodes in unusual state. We may also skip
+		 * inodes without pages but we deliberately won't in case
+		 * we need to reschedule to avoid softlockups.
+		 */
+		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
+		    (mapping_empty(inode->i_mapping) && !need_resched())) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		spin_unlock(&sb->s_inode_list_lock);
+
+		invalidator(inode->i_mapping);
+		iput(toput_inode);
+		toput_inode = inode;
+
+		cond_resched();
+		spin_lock(&sb->s_inode_list_lock);
+	}
+	spin_unlock(&sb->s_inode_list_lock);
+	iput(toput_inode);
+}
+EXPORT_SYMBOL(super_drop_pagecache);
+
 static void __iterate_supers(void (*f)(struct super_block *))
 {
 	struct super_block *sb, *p = NULL;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9eced4cc286e..0e60c494688e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3292,6 +3292,7 @@ extern struct super_block *get_super(struct block_device *);
 extern struct super_block *get_active_super(struct block_device *bdev);
 extern void drop_super(struct super_block *sb);
 extern void drop_super_exclusive(struct super_block *sb);
+void super_drop_pagecache(struct super_block *sb, void *unused);
 extern void iterate_supers(void (*)(struct super_block *, void *), void *);
 extern void iterate_supers_type(struct file_system_type *,
 			        void (*)(struct super_block *, void *), void *);
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 0178b2040ea3..8879c141b117 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -27,6 +27,7 @@ static inline void invalidate_remote_inode(struct inode *inode)
 	    S_ISLNK(inode->i_mode))
 		invalidate_mapping_pages(inode->i_mapping, 0, -1);
 }
+int invalidate_inode_pages(struct address_space *mapping);
 int invalidate_inode_pages2(struct address_space *mapping);
 int invalidate_inode_pages2_range(struct address_space *mapping,
 		pgoff_t start, pgoff_t end);
diff --git a/mm/truncate.c b/mm/truncate.c
index 0b0708bf935f..3016258d41e7 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -548,12 +548,13 @@ unsigned long invalidate_mapping_pagevec(struct address_space *mapping,
 }
 
 /**
- * invalidate_mapping_pages - Invalidate all clean, unlocked cache of one inode
+ * invalidate_mapping_pages - Invalidate range of clean, unlocked cache of one
+ *			      inode
  * @mapping: the address_space which holds the cache to invalidate
  * @start: the offset 'from' which to invalidate
  * @end: the offset 'to' which to invalidate (inclusive)
  *
- * This function removes pages that are clean, unmapped and unlocked,
+ * This function removes range of pages that are clean, unmapped and unlocked,
  * as well as shadow entries. It will not block on IO activity.
  *
  * If you want to remove all the pages of one inode, regardless of
@@ -568,6 +569,21 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
 }
 EXPORT_SYMBOL(invalidate_mapping_pages);
 
+/**
+ * invalidate_inode_pages - Invalidate all clean, unlocked cache of one inode
+ * @mapping: the address_space which holds the cache to invalidate
+ *
+ * This function removes all pages that are clean, unmapped and unlocked,
+ * as well as shadow entries. It will not block on IO activity.
+ */
+int invalidate_inode_pages(struct address_space *mapping)
+{
+	invalidate_mapping_pages(mapping, 0, -1);
+
+	return 0;
+}
+EXPORT_SYMBOL(invalidate_inode_pages);
+
 /*
  * This is like invalidate_inode_page(), except it ignores the page's
  * refcount.  We do this because invalidate_inode_pages2() needs stronger
-- 
2.37.3

[PATCH 3/3] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind

[Shiyang Ruan]

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_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.

[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>
---
 drivers/dax/super.c         |  3 ++-
 fs/xfs/xfs_notify_failure.c | 28 +++++++++++++++++++++++++++-
 include/linux/mm.h          |  1 +
 3 files changed, 30 insertions(+), 2 deletions(-)

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 3830f908e215..5c1e678a1285 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;
@@ -77,6 +78,9 @@ xfs_dax_failure_fn(
 
 	if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) ||
 	    (rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) {
+		/* 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;
 	}
@@ -168,7 +172,9 @@ xfs_dax_notify_ddev_failure(
 		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;
 }
 
@@ -182,12 +188,24 @@ 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()!");
 		return -EIO;
 	}
 
+	if (mf_flags & MF_MEM_PRE_REMOVE) {
+		xfs_info(mp, "device is about to be removed!");
+		down_write(&mp->m_super->s_umount);
+		error = sync_filesystem(mp->m_super);
+		/* invalidate_inode_pages2() invalidates dax mapping */
+		super_drop_pagecache(mp->m_super, invalidate_inode_pages2);
+		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_debug(mp,
 			 "notify_failure() not supported on realtime device!");
@@ -196,6 +214,8 @@ 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 +229,12 @@ 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;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 21f8b27bd9fd..9122a1c57dd2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3183,6 +3183,7 @@ 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);
-- 
2.37.3

Re: [PATCH v9 0/3] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind

[Shiyang Ruan]

Hi,

Ping

在 2022/9/25 21:33, Shiyang Ruan 写道:
> Changes since v8:
>    1. P2: rename drop_pagecache_sb() to super_drop_pagecache().
>    2. P2: let super_drop_pagecache() accept invalidate method.
>    3. P3: invalidate all dax mappings by invalidate_inode_pages2().
>    4. P3: shutdown the filesystem when it is to be removed.
>    5. Rebase on 6.0-rc6 + Darrick's patch[1] + Dan's patch[2].
> 
> [1]: https://lore.kernel.org/linux-xfs/Yv5wIa2crHioYeRr@magnolia/
> [2]: https://lore.kernel.org/linux-xfs/166153426798.2758201.15108211981034512993.stgit@dwillia2-xfh.jf.intel.com/
> 
> Shiyang Ruan (3):
>    xfs: fix the calculation of length and end
>    fs: move drop_pagecache_sb() for others to use
>    mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind
> 
>   drivers/dax/super.c         |  3 ++-
>   fs/drop_caches.c            | 35 ++----------------------------
>   fs/super.c                  | 43 +++++++++++++++++++++++++++++++++++++
>   fs/xfs/xfs_notify_failure.c | 36 ++++++++++++++++++++++++++-----
>   include/linux/fs.h          |  1 +
>   include/linux/mm.h          |  1 +
>   include/linux/pagemap.h     |  1 +
>   mm/truncate.c               | 20 +++++++++++++++--
>   8 files changed, 99 insertions(+), 41 deletions(-)
> 

Re: [PATCH v9 0/3] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind

[Shiyang Ruan]

Ping again~

在 2022/9/30 11:28, Shiyang Ruan 写道:
> Hi,
> 
> Ping
> 
> 在 2022/9/25 21:33, Shiyang Ruan 写道:
>> Changes since v8:
>>    1. P2: rename drop_pagecache_sb() to super_drop_pagecache().
>>    2. P2: let super_drop_pagecache() accept invalidate method.
>>    3. P3: invalidate all dax mappings by invalidate_inode_pages2().
>>    4. P3: shutdown the filesystem when it is to be removed.
>>    5. Rebase on 6.0-rc6 + Darrick's patch[1] + Dan's patch[2].
>>
>> [1]: https://lore.kernel.org/linux-xfs/Yv5wIa2crHioYeRr@magnolia/
>> [2]: 
>> https://lore.kernel.org/linux-xfs/166153426798.2758201.15108211981034512993.stgit@dwillia2-xfh.jf.intel.com/
>>
>> Shiyang Ruan (3):
>>    xfs: fix the calculation of length and end
>>    fs: move drop_pagecache_sb() for others to use
>>    mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind
>>
>>   drivers/dax/super.c         |  3 ++-
>>   fs/drop_caches.c            | 35 ++----------------------------
>>   fs/super.c                  | 43 +++++++++++++++++++++++++++++++++++++
>>   fs/xfs/xfs_notify_failure.c | 36 ++++++++++++++++++++++++++-----
>>   include/linux/fs.h          |  1 +
>>   include/linux/mm.h          |  1 +
>>   include/linux/pagemap.h     |  1 +
>>   mm/truncate.c               | 20 +++++++++++++++--
>>   8 files changed, 99 insertions(+), 41 deletions(-)
>>