The patch titled
Subject: dax: improve comment about truncate race
has been added to the -mm tree. Its filename is
dax-improve-comment-about-truncate-race.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/dax-improve-comment-about-truncate-race.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/dax-improve-comment-about-truncate-race.patch
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------------------------------------------------------
From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Subject: dax: improve comment about truncate race
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@xxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff -puN fs/dax.c~dax-improve-comment-about-truncate-race fs/dax.c
--- a/fs/dax.c~dax-improve-comment-about-truncate-race
+++ a/fs/dax.c
@@ -553,7 +553,12 @@ int __dax_pmd_fault(struct vm_area_struc
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;
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxxxx are
mm-make-gup-handle-pfn-mapping-unless-foll_get-is-requested.patch
mm-make-gup-handle-pfn-mapping-unless-foll_get-is-requested-fix.patch
dax-move-dax-related-functions-to-a-new-header.patch
dax-revert-userfaultfd-change.patch
thp-prepare-for-dax-huge-pages.patch
thp-prepare-for-dax-huge-pages-fix.patch
mm-add-a-pmd_fault-handler.patch
mm-export-various-functions-for-the-benefit-of-dax.patch
mm-add-vmf_insert_pfn_pmd.patch
dax-add-huge-page-fault-support.patch
ext2-huge-page-fault-support.patch
ext4-huge-page-fault-support.patch
xfs-huge-page-fault-support.patch
ext4-use-ext4_get_block_write-for-dax.patch
thp-change-insert_pfns-return-type-to-void.patch
dax-improve-comment-about-truncate-race.patch
ext4-add-ext4_get_block_dax.patch
ext4-start-transaction-before-calling-into-dax.patch
dax-fix-race-between-simultaneous-faults.patch
thp-decrement-refcount-on-huge-zero-page-if-it-is-split.patch
thp-fix-zap_huge_pmd-for-dax.patch
dax-dont-use-set_huge_zero_page.patch
dax-ensure-that-zero-pages-are-removed-from-other-processes.patch
dax-use-linear_page_index.patch
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