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From: Matthew Wilcox <matthew.r.wilcox@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Cc: Matthew Wilcox <willy@linux.intel.com>
Subject: [PATCH 03/11] dax: Improve comment about truncate race
Date: Tue,  4 Aug 2015 15:57:57 -0400	[thread overview]
Message-ID: <1438718285-21168-4-git-send-email-matthew.r.wilcox@intel.com> (raw)
In-Reply-To: <1438718285-21168-1-git-send-email-matthew.r.wilcox@intel.com>

From: Matthew Wilcox <willy@linux.intel.com>

Jan Kara pointed out I should be more explicit here about the perils of
racing against truncate.  The comment is mostly the same as for the PTE
case.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
---
 fs/dax.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index 15f8ffc..0a13118 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -553,7 +553,12 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE)
 		goto fallback;
 
-	/* Guard against a race with truncate */
+	/*
+	 * If a truncate happened while we were allocating blocks, we may
+	 * leave blocks allocated to the file that are beyond EOF.  We can't
+	 * take i_mutex here, so just leave them hanging; they'll be freed
+	 * when the file is deleted.
+	 */
 	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	if (pgoff >= size) {
 		result = VM_FAULT_SIGBUS;
-- 
2.1.4


WARNING: multiple messages have this Message-ID (diff)
From: Matthew Wilcox <matthew.r.wilcox@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Cc: Matthew Wilcox <willy@linux.intel.com>
Subject: [PATCH 03/11] dax: Improve comment about truncate race
Date: Tue,  4 Aug 2015 15:57:57 -0400	[thread overview]
Message-ID: <1438718285-21168-4-git-send-email-matthew.r.wilcox@intel.com> (raw)
In-Reply-To: <1438718285-21168-1-git-send-email-matthew.r.wilcox@intel.com>

From: Matthew Wilcox <willy@linux.intel.com>

Jan Kara pointed out I should be more explicit here about the perils of
racing against truncate.  The comment is mostly the same as for the PTE
case.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
---
 fs/dax.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index 15f8ffc..0a13118 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -553,7 +553,12 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE)
 		goto fallback;
 
-	/* Guard against a race with truncate */
+	/*
+	 * If a truncate happened while we were allocating blocks, we may
+	 * leave blocks allocated to the file that are beyond EOF.  We can't
+	 * take i_mutex here, so just leave them hanging; they'll be freed
+	 * when the file is deleted.
+	 */
 	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	if (pgoff >= size) {
 		result = VM_FAULT_SIGBUS;
-- 
2.1.4

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  parent reply	other threads:[~2015-08-04 19:58 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-04 19:57 [PATCH 00/11] DAX fixes for 4.3 Matthew Wilcox
2015-08-04 19:57 ` Matthew Wilcox
2015-08-04 19:57 ` [PATCH 01/11] ext4: Use ext4_get_block_write() for DAX Matthew Wilcox
2015-08-04 19:57   ` Matthew Wilcox
2015-08-04 19:57 ` [PATCH 02/11] thp: Change insert_pfn's return type to void Matthew Wilcox
2015-08-04 19:57   ` Matthew Wilcox
2015-08-04 19:57 ` Matthew Wilcox [this message]
2015-08-04 19:57   ` [PATCH 03/11] dax: Improve comment about truncate race Matthew Wilcox
2015-08-04 19:57 ` [PATCH 04/11] ext4: Add ext4_get_block_dax() Matthew Wilcox
2015-08-04 19:57   ` Matthew Wilcox
2015-08-05  2:03   ` Dave Chinner
2015-08-05  2:03     ` Dave Chinner
2015-08-05 15:19     ` Matthew Wilcox
2015-08-05 15:19       ` Matthew Wilcox
2015-08-04 19:57 ` [PATCH 05/11] ext4: Start transaction before calling into DAX Matthew Wilcox
2015-08-04 19:57   ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 06/11] dax: Fix race between simultaneous faults Matthew Wilcox
2015-08-04 19:58   ` Matthew Wilcox
2015-08-05 11:43   ` Kirill A. Shutemov
2015-08-05 11:43     ` Kirill A. Shutemov
2015-08-04 19:58 ` [PATCH 07/11] thp: Decrement refcount on huge zero page if it is split Matthew Wilcox
2015-08-04 19:58   ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 08/11] thp: Fix zap_huge_pmd() for DAX Matthew Wilcox
2015-08-04 19:58   ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 09/11] dax: Don't use set_huge_zero_page() Matthew Wilcox
2015-08-04 19:58   ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 10/11] dax: Ensure that zero pages are removed from other processes Matthew Wilcox
2015-08-04 19:58   ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 11/11] dax: Use linear_page_index() Matthew Wilcox
2015-08-04 19:58   ` Matthew Wilcox

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