[PATCH v2] ceph: fix copy_file_range error path in short copies

[Luis Henriques]

When there's an error in the copying loop but some bytes have already been
copied into the destination file, it is necessary to dirty the caps and
eventually update the MDS with the file metadata (timestamps, size).  This
patch fixes this error path.

Another issue this patch fixes is the destination file size being reported
to the MDS.  If we're on the error path but the amount of bytes written
has already changed the destination file size, the offset to use is
dst_off and not endoff.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Luis Henriques <lhenriques@xxxxxxxx>
---
 fs/ceph/file.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 11929d2bb594..f7f8cb6c243f 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -2104,9 +2104,16 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
 			CEPH_OSD_OP_FLAG_FADVISE_DONTNEED, 0);
 		if (err) {
 			dout("ceph_osdc_copy_from returned %d\n", err);
-			if (!ret)
+			/*
+			 * If we haven't done any copy yet, just exit with the
+			 * error code; otherwise, return the number of bytes
+			 * already copied, update metadata and dirty caps.
+			 */
+			if (!ret) {
 				ret = err;
-			goto out_caps;
+				goto out_caps;
+			}
+			goto update_dst_inode;
 		}
 		len -= object_size;
 		src_off += object_size;
@@ -2118,16 +2125,17 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
 		/* We still need one final local copy */
 		do_final_copy = true;
 
+update_dst_inode:
 	file_update_time(dst_file);
 	inode_inc_iversion_raw(dst_inode);
 
-	if (endoff > size) {
+	if (dst_off > size) {
 		int caps_flags = 0;
 
 		/* Let the MDS know about dst file size change */
-		if (ceph_quota_is_max_bytes_approaching(dst_inode, endoff))
+		if (ceph_quota_is_max_bytes_approaching(dst_inode, dst_off))
 			caps_flags |= CHECK_CAPS_NODELAY;
-		if (ceph_inode_set_size(dst_inode, endoff))
+		if (ceph_inode_set_size(dst_inode, dst_off))
 			caps_flags |= CHECK_CAPS_AUTHONLY;
 		if (caps_flags)
 			ceph_check_caps(dst_ci, caps_flags, NULL);