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9p: Fix v9fs_issue_write() to update i_size and remote_i_size

PATCH New Dominique Martinet 1 participant 1 message Sep 12

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Dominique Martinet

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PATCH 1/1 9p: Fix v9fs_issue_write() to update i_size and remote_i_size

From: David Howells <[email protected]>

Fix v9fs_issue_write() to update i_size and remote_i_size to the new size of the server file if we made it larger, using the start fpos and the count returned by p9_client_write() to calculate the new minimum file size.

This assumes that if the 9P server makes a short write (say it hits ENOSPC), a reduced count is returned.

Fixes 5fb70e7275a6 ("netfs, 9p: Implement helpers for new write code")
Reported-by Michael Mulqueen <[email protected]>
Closes https://lore.kernel.org/r/[email protected]/ open here
Cc [email protected]
Signed-off-by David Howells <[email protected]>

Message-ID: <[email protected]>

Signed-off-by Dominique Martinet <[email protected]>

---
I'm resending this as a patch to get sashiko to run on it, please disregard this email and reply to the original thread (Closes link above) if you have concerns about it.
(well, I guess either David or me will see it either way, but it's easier to follow if it's all in the same thread)

 fs/9p/vfs_addr.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)
fs/9p/vfs_addr.c +27 -1
index 1ac0b3dcc077..13cf87a5f90c 100644
@@ -54,11 +54,37 @@ static void v9fs_begin_writeback(struct netfs_io_request *wreq)
 static void v9fs_issue_write(struct netfs_io_subrequest *subreq)
 {
 	struct p9_fid *fid = subreq->rreq->netfs_priv;
+	struct inode *inode = subreq->rreq->inode;
+	struct netfs_inode *ictx = netfs_inode(inode);
 	int err, len;
 
 	len = p9_client_write(fid, subreq->start, &subreq->io_iter, &err);
-	if (len > 0)
+	if (len > 0) {
+		uoff_t end = subreq->start + len, i_size, remote, zp;
+		bool set = false;
+
+		spin_lock(&inode->i_lock);
+
+		/* We can read the sizes directly as we hold i_lock. */
+		i_size = inode->i_size;
+		remote = ictx->_remote_i_size;
+		zp = ictx->_zero_point;
+
+		if (end > i_size) {
+			i_size = end;
+			set = true;
+		}
+		if (end > remote) {
+			remote = end;
+			set = true;
+		}
+
+		if (set)
+			netfs_write_sizes(inode, i_size, remote, zp);
+		spin_unlock(&inode->i_lock);
+
 		__set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
+	}
 	netfs_write_subrequest_terminated(subreq, len ?: err);
 }
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