From: Jan Kara <jack@suse.cz>
To: linux-nvdimm@lists.01.org
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 3/3] dax: Clear dirty entry tags on cache flush
Date: Thu, 23 Jun 2016 12:47:28 +0200 [thread overview]
Message-ID: <20160623104728.GA25982@quack2.suse.cz> (raw)
In-Reply-To: <1466523915-14644-4-git-send-email-jack@suse.cz>
Hi,
the previous version had a bug which manifested itself on i586. Attached is
a new version for the patch if someone is interested.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz>
To: linux-nvdimm@lists.01.org
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
Dan Williams <dan.j.williams@intel.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 3/3] dax: Clear dirty entry tags on cache flush
Date: Thu, 23 Jun 2016 12:47:28 +0200 [thread overview]
Message-ID: <20160623104728.GA25982@quack2.suse.cz> (raw)
In-Reply-To: <1466523915-14644-4-git-send-email-jack@suse.cz>
[-- Attachment #1: Type: text/plain, Size: 193 bytes --]
Hi,
the previous version had a bug which manifested itself on i586. Attached is
a new version for the patch if someone is interested.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
[-- Attachment #2: 0003-dax-Clear-dirty-entry-tags-on-cache-flush.patch --]
[-- Type: text/x-patch, Size: 3694 bytes --]
>From a55cfe2dc362826f5e81beb6c7607f0daa5d317d Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Fri, 17 Jun 2016 17:14:48 +0200
Subject: [PATCH 3/3] dax: Clear dirty entry tags on cache flush
Currently we never clear dirty tags in DAX mappings and thus address
ranges to flush accumulate. Now that we have locking of radix tree
entries, we have all the locking necessary to reliably clear the radix
tree dirty tag when flushing caches for corresponding address range.
Similarly to page_mkclean() we also have to write-protect pages to get a
page fault when the page is next written to so that we can mark the
entry dirty again.
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/dax.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 68 insertions(+), 1 deletion(-)
diff --git a/fs/dax.c b/fs/dax.c
index 5209f8cd0bee..4b31658660dc 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -31,6 +31,7 @@
#include <linux/vmstat.h>
#include <linux/pfn_t.h>
#include <linux/sizes.h>
+#include <linux/mmu_notifier.h>
/*
* We use lowest available bit in exceptional entry for locking, other two
@@ -665,6 +666,59 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
return new_entry;
}
+static inline unsigned long
+pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
+{
+ unsigned long address;
+
+ address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+ VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+ return address;
+}
+
+/* Walk all mappings of a given index of a file and writeprotect them */
+static void dax_mapping_entry_mkclean(struct address_space *mapping,
+ pgoff_t index, unsigned long pfn)
+{
+ struct vm_area_struct *vma;
+ pte_t *ptep;
+ pte_t pte;
+ spinlock_t *ptl;
+ bool changed;
+
+ i_mmap_lock_read(mapping);
+ vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) {
+ unsigned long address;
+
+ cond_resched();
+
+ if (!(vma->vm_flags & VM_SHARED))
+ continue;
+
+ address = pgoff_address(index, vma);
+ changed = false;
+ if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
+ continue;
+ if (pfn != pte_pfn(*ptep))
+ goto unlock;
+ if (!pte_dirty(*ptep) && !pte_write(*ptep))
+ goto unlock;
+
+ flush_cache_page(vma, address, pfn);
+ pte = ptep_clear_flush(vma, address, ptep);
+ pte = pte_wrprotect(pte);
+ pte = pte_mkclean(pte);
+ set_pte_at(vma->vm_mm, address, ptep, pte);
+ changed = true;
+unlock:
+ pte_unmap_unlock(ptep, ptl);
+
+ if (changed)
+ mmu_notifier_invalidate_page(vma->vm_mm, address);
+ }
+ i_mmap_unlock_read(mapping);
+}
+
static int dax_writeback_one(struct block_device *bdev,
struct address_space *mapping, pgoff_t index, void *entry)
{
@@ -723,17 +777,30 @@ static int dax_writeback_one(struct block_device *bdev,
* eventually calls cond_resched().
*/
ret = dax_map_atomic(bdev, &dax);
- if (ret < 0)
+ if (ret < 0) {
+ put_locked_mapping_entry(mapping, index, entry);
return ret;
+ }
if (WARN_ON_ONCE(ret < dax.size)) {
ret = -EIO;
goto unmap;
}
+ dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(dax.pfn));
wb_cache_pmem(dax.addr, dax.size);
+ /*
+ * After we have flushed the cache, we can clear the dirty tag. There
+ * cannot be new dirty data in the pfn after the flush has completed as
+ * the pfn mappings are writeprotected and fault waits for mapping
+ * entry lock.
+ */
+ spin_lock_irq(&mapping->tree_lock);
+ radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
+ spin_unlock_irq(&mapping->tree_lock);
unmap:
dax_unmap_atomic(bdev, &dax);
+ put_locked_mapping_entry(mapping, index, entry);
return ret;
put_unlock:
--
2.6.6
WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz>
To: linux-nvdimm@lists.01.org
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
Dan Williams <dan.j.williams@intel.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 3/3] dax: Clear dirty entry tags on cache flush
Date: Thu, 23 Jun 2016 12:47:28 +0200 [thread overview]
Message-ID: <20160623104728.GA25982@quack2.suse.cz> (raw)
In-Reply-To: <1466523915-14644-4-git-send-email-jack@suse.cz>
[-- Attachment #1: Type: text/plain, Size: 193 bytes --]
Hi,
the previous version had a bug which manifested itself on i586. Attached is
a new version for the patch if someone is interested.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
[-- Attachment #2: 0003-dax-Clear-dirty-entry-tags-on-cache-flush.patch --]
[-- Type: text/x-patch, Size: 0 bytes --]
next prev parent reply other threads:[~2016-06-23 10:48 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-21 15:45 [PATCH 0/3 v1] dax: Clear dirty bits after flushing caches Jan Kara
2016-06-21 15:45 ` Jan Kara
2016-06-21 15:45 ` [PATCH 1/3] dax: Make cache flushing protected by entry lock Jan Kara
2016-06-21 15:45 ` Jan Kara
2016-06-24 21:44 ` Ross Zwisler
2016-06-24 21:44 ` Ross Zwisler
2016-06-29 20:28 ` Jan Kara
2016-06-29 20:28 ` Jan Kara
2016-06-21 15:45 ` [PATCH 2/3] mm: Export follow_pte() Jan Kara
2016-06-21 15:45 ` Jan Kara
2016-06-24 21:55 ` Ross Zwisler
2016-06-24 21:55 ` Ross Zwisler
2016-06-29 20:29 ` Jan Kara
2016-06-29 20:29 ` Jan Kara
2016-06-21 15:45 ` [PATCH 3/3] dax: Clear dirty entry tags on cache flush Jan Kara
2016-06-21 15:45 ` Jan Kara
2016-06-21 17:31 ` kbuild test robot
2016-06-21 17:31 ` kbuild test robot
2016-06-21 17:31 ` kbuild test robot
2016-06-21 20:59 ` kbuild test robot
2016-06-21 20:59 ` kbuild test robot
2016-06-21 20:59 ` kbuild test robot
2016-06-23 10:47 ` Jan Kara [this message]
2016-06-23 10:47 ` Jan Kara
2016-06-23 10:47 ` Jan Kara
2016-06-28 21:38 ` Ross Zwisler
2016-06-28 21:38 ` Ross Zwisler
2016-06-29 20:47 ` Jan Kara
2016-06-29 20:47 ` Jan Kara
2016-06-28 21:41 ` [PATCH 0/3 v1] dax: Clear dirty bits after flushing caches Ross Zwisler
2016-06-28 21:41 ` Ross Zwisler
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