Messages in this thread Patch in this message | | | From | Matthew Wilcox <> | Subject | [PATCH 03/11] dax: Improve comment about truncate race | Date | Tue, 4 Aug 2015 15:57:57 -0400 |
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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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