If prepare_write fails with AOP_TRUNCATED_PAGE, or if commit_write fails, then
we may have failed the write operation despite prepare_write having
instantiated blocks past i_size. Fix this, and consolidate the trimming into
one place.
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -1911,22 +1911,9 @@ generic_file_buffered_write(struct kiocb
}
status = a_ops->prepare_write(file, page, offset, offset+bytes);
- if (unlikely(status)) {
- loff_t isize = i_size_read(inode);
+ if (unlikely(status))
+ goto fs_write_aop_error;
- if (status != AOP_TRUNCATED_PAGE)
- unlock_page(page);
- page_cache_release(page);
- if (status == AOP_TRUNCATED_PAGE)
- continue;
- /*
- * prepare_write() may have instantiated a few blocks
- * outside i_size. Trim these off again.
- */
- if (pos + bytes > isize)
- vmtruncate(inode, isize);
- break;
- }
if (likely(nr_segs == 1))
copied = filemap_copy_from_user(page, offset,
buf, bytes);
@@ -1935,10 +1922,9 @@ generic_file_buffered_write(struct kiocb
cur_iov, iov_offset, bytes);
flush_dcache_page(page);
status = a_ops->commit_write(file, page, offset, offset+bytes);
- if (status == AOP_TRUNCATED_PAGE) {
- page_cache_release(page);
- continue;
- }
+ if (unlikely(status))
+ goto fs_write_aop_error;
+
if (likely(copied > 0)) {
if (!status)
status = copied;
@@ -1969,6 +1955,25 @@ generic_file_buffered_write(struct kiocb
break;
balance_dirty_pages_ratelimited(mapping);
cond_resched();
+ continue;
+
+fs_write_aop_error:
+ if (status != AOP_TRUNCATED_PAGE)
+ unlock_page(page);
+ page_cache_release(page);
+
+ /*
+ * prepare_write() may have instantiated a few blocks
+ * outside i_size. Trim these off again. Don't need
+ * i_size_read because we hold i_mutex.
+ */
+ if (pos + bytes > inode->i_size)
+ vmtruncate(inode, inode->i_size);
+ if (status == AOP_TRUNCATED_PAGE)
+ continue;
+ else
+ break;
+
} while (count);
*ppos = pos;
-
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