Btrfs: Fix some data=ordered related data corruptions

Stress testing was showing data checksum errors, most of which were caused
by a lookup bug in the extent_map tree.  The tree was caching the last
pointer returned, and searches would check the last pointer first.

But, search callers also expect the search to return the very first
matching extent in the range, which wasn't always true with the last
pointer usage.

For now, the code to cache the last return value is just removed.  It is
easy to fix, but I think lookups are rare enough that it isn't required anymore.

This commit also replaces do_sync_mapping_range with a local copy of the
related functions.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 97 insertions, 18 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 0d87795..830dbae 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -19,6 +19,8 @@
 #include <linux/gfp.h>
 #include <linux/slab.h>
 #include <linux/blkdev.h>
+#include <linux/writeback.h>
+#include <linux/pagevec.h>
 #include "ctree.h"
 #include "transaction.h"
 #include "btrfs_inode.h"
@@ -307,12 +309,7 @@ void btrfs_start_ordered_extent(struct inode *inode,
 	 * start IO on any dirty ones so the wait doesn't stall waiting
 	 * for pdflush to find them
 	 */
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
-	do_sync_file_range(file, start, end, SYNC_FILE_RANGE_WRITE);
-#else
-	do_sync_mapping_range(inode->i_mapping, start, end,
-			      SYNC_FILE_RANGE_WRITE);
-#endif
+	btrfs_fdatawrite_range(inode->i_mapping, start, end, WB_SYNC_NONE);
 	if (wait)
 		wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE,
 						 &entry->flags));
@@ -327,28 +324,26 @@ void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
 	u64 orig_end;
 	u64 wait_end;
 	struct btrfs_ordered_extent *ordered;
-	u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
 
 	if (start + len < start) {
-		wait_end = (inode->i_size + mask) & ~mask;
-		orig_end = (u64)-1;
+		orig_end = INT_LIMIT(loff_t);
 	} else {
 		orig_end = start + len - 1;
-		wait_end = orig_end;
+		if (orig_end > INT_LIMIT(loff_t))
+			orig_end = INT_LIMIT(loff_t);
 	}
+	wait_end = orig_end;
 again:
 	/* start IO across the range first to instantiate any delalloc
 	 * extents
 	 */
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
-	do_sync_file_range(file, start, wait_end, SYNC_FILE_RANGE_WRITE);
-#else
-	do_sync_mapping_range(inode->i_mapping, start, wait_end,
-			      SYNC_FILE_RANGE_WRITE);
-#endif
-	end = orig_end;
-	wait_on_extent_writeback(&BTRFS_I(inode)->io_tree, start, orig_end);
+	btrfs_fdatawrite_range(inode->i_mapping, start, orig_end, WB_SYNC_NONE);
+
+	btrfs_wait_on_page_writeback_range(inode->i_mapping,
+					   start >> PAGE_CACHE_SHIFT,
+					   orig_end >> PAGE_CACHE_SHIFT);
 
+	end = orig_end;
 	while(1) {
 		ordered = btrfs_lookup_first_ordered_extent(inode, end);
 		if (!ordered) {
@@ -565,3 +560,87 @@ out:
 	return ret;
 }
 
+
+/**
+ * taken from mm/filemap.c because it isn't exported
+ *
+ * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
+ * @mapping:	address space structure to write
+ * @start:	offset in bytes where the range starts
+ * @end:	offset in bytes where the range ends (inclusive)
+ * @sync_mode:	enable synchronous operation
+ *
+ * Start writeback against all of a mapping's dirty pages that lie
+ * within the byte offsets <start, end> inclusive.
+ *
+ * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
+ * opposed to a regular memory cleansing writeback.  The difference between
+ * these two operations is that if a dirty page/buffer is encountered, it must
+ * be waited upon, and not just skipped over.
+ */
+int btrfs_fdatawrite_range(struct address_space *mapping, loff_t start,
+			   loff_t end, int sync_mode)
+{
+	struct writeback_control wbc = {
+		.sync_mode = sync_mode,
+		.nr_to_write = mapping->nrpages * 2,
+		.range_start = start,
+		.range_end = end,
+		.for_writepages = 1,
+	};
+	return btrfs_writepages(mapping, &wbc);
+}
+
+/**
+ * taken from mm/filemap.c because it isn't exported
+ *
+ * wait_on_page_writeback_range - wait for writeback to complete
+ * @mapping:	target address_space
+ * @start:	beginning page index
+ * @end:	ending page index
+ *
+ * Wait for writeback to complete against pages indexed by start->end
+ * inclusive
+ */
+int btrfs_wait_on_page_writeback_range(struct address_space *mapping,
+				       pgoff_t start, pgoff_t end)
+{
+	struct pagevec pvec;
+	int nr_pages;
+	int ret = 0;
+	pgoff_t index;
+
+	if (end < start)
+		return 0;
+
+	pagevec_init(&pvec, 0);
+	index = start;
+	while ((index <= end) &&
+			(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+			PAGECACHE_TAG_WRITEBACK,
+			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
+		unsigned i;
+
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+
+			/* until radix tree lookup accepts end_index */
+			if (page->index > end)
+				continue;
+
+			wait_on_page_writeback(page);
+			if (PageError(page))
+				ret = -EIO;
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+
+	/* Check for outstanding write errors */
+	if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
+		ret = -ENOSPC;
+	if (test_and_clear_bit(AS_EIO, &mapping->flags))
+		ret = -EIO;
+
+	return ret;
+}