[Ocfs2-devel] [PATCH 3/4] ocfs2: fix disk file size and memory file size mismatch

[Ryan Ding]

When doing append direct write in an already allocated cluster, and fast path
in ocfs2_dio_get_block() is triggered, function ocfs2_dio_end_io_write() will
be skipped as there is no context allocated. So disk file size will not be
changed as it should be.
The solution is to skip fast path when we are about to change file size.

Fixes: af1310367f41 ("ocfs2: fix sparse file & data ordering issue in direct io.")
Signed-off-by: Ryan Ding <ryan.ding at oracle.com>
---
 fs/ocfs2/aops.c |   27 +++++++++++++++++----------
 1 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index d571509..f33cfe4 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -2167,19 +2167,26 @@ static int ocfs2_dio_get_block(struct inode *inode, sector_t iblock,
 	mlog(0, "get block of %lu at %llu:%u req %u\n",
 			inode->i_ino, pos, len, total_len);
 
-	down_read(&oi->ip_alloc_sem);
-	/* This is the fast path for re-write. */
-	ret = ocfs2_get_block(inode, iblock, bh_result, create);
+	/*
+	 * Because we need to change file size in ocfs2_dio_end_io_write(), or
+	 * we may need to add it to orphan dir. So can not fall to fast path
+	 * while file size will be changed.
+	 */
+	if (pos + total_len <= i_size_read(inode)) {
+		down_read(&oi->ip_alloc_sem);
+		/* This is the fast path for re-write. */
+		ret = ocfs2_get_block(inode, iblock, bh_result, create);
 
-	up_read(&oi->ip_alloc_sem);
+		up_read(&oi->ip_alloc_sem);
 
-	if (buffer_mapped(bh_result) &&
-	    !buffer_new(bh_result) &&
-	    ret == 0)
-		goto out;
+		if (buffer_mapped(bh_result) &&
+		    !buffer_new(bh_result) &&
+		    ret == 0)
+			goto out;
 
-	/* Clear state set by ocfs2_get_block. */
-	bh_result->b_state = 0;
+		/* Clear state set by ocfs2_get_block. */
+		bh_result->b_state = 0;
+	}
 
 	dwc = ocfs2_dio_alloc_write_ctx(bh_result, &first_get_block);
 	if (unlikely(dwc == NULL)) {
-- 
1.7.1