linux-nfs.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH 1/1] NFS: Sync the correct byte range during synchronous writes
@ 2017-09-07 13:29 tarangg
  2017-09-07 15:12 ` Trond Myklebust
  0 siblings, 1 reply; 2+ messages in thread
From: tarangg @ 2017-09-07 13:29 UTC (permalink / raw)
  To: trond.myklebust; +Cc: jsstraus, linux-nfs, Tarang Gupta

Since commit 18290650b1c8 ("NFS: Move buffered I/O locking into
nfs_file_write()") nfs_file_write() has not flushed the correct byte
range during synchronous writes.  generic_write_sync() expects that
iocb->ki_pos points to the right edge of the range rather than the
left edge.

To replicate the problem, open a file with O_DSYNC, have the client
write at increasing offsets, and then print the successful offsets.
Block port 2049 partway through that sequence, and observe that the
client application indicates successful writes in advance of what the
server received.

Fixes: 18290650b1c8 ("NFS: Move buffered I/O locking into nfs_file_write()")
Signed-off-by: Jacob Strauss <jsstraus@amazon.com>
Signed-off-by: Tarang Gupta <tarangg@amazon.com>
Tested-by: Tarang Gupta <tarangg@amazon.com>
---
 fs/nfs/file.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index af330c31f627..a85d1cf9b4a8 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -631,11 +631,11 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
 	if (result <= 0)
 		goto out;
 
-	result = generic_write_sync(iocb, result);
-	if (result < 0)
-		goto out;
 	written = result;
 	iocb->ki_pos += written;
+	result = generic_write_sync(iocb, written);
+	if (result < 0)
+		goto out;
 
 	/* Return error values */
 	if (nfs_need_check_write(file, inode)) {
-- 
2.11.0 (Apple Git-81)


^ permalink raw reply related	[flat|nested] 2+ messages in thread
end of thread, other threads:[~2017-09-07 15:12 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-09-07 13:29 [PATCH 1/1] NFS: Sync the correct byte range during synchronous writes tarangg
2017-09-07 15:12 ` Trond Myklebust

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).