lkml.org 
[lkml]   [2015]   [Aug]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 03/11] dax: Improve comment about truncate race
Date
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


\
 
 \ /
  Last update: 2015-08-04 22:21    [W:0.119 / U:0.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site