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authorMatthew Wilcox <willy@linux.intel.com>2015-09-08 14:59:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-08 15:35:28 -0700
commit84c4e5e675408b6fb7d74eec7da9a4a5698b50af (patch)
tree061bb263cd0d084e8e31fee41bf6e47c3397d7b6 /fs
parentae18d6dcf57b56b984ff27fd55b4e2caf5bfbd44 (diff)
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@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/dax.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/dax.c b/fs/dax.c
index 2deed64b7eea..c694117a7062 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;

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