Patch "NFS: Fix error handling for O_DIRECT write scheduling" has been added to the 6.5-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    NFS: Fix error handling for O_DIRECT write scheduling

to the 6.5-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfs-fix-error-handling-for-o_direct-write-scheduling.patch
and it can be found in the queue-6.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 2eb6f426a58cb209a3f528fb8fc4a6446d6eaeeb
Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Date:   Mon Sep 4 12:34:37 2023 -0400

    NFS: Fix error handling for O_DIRECT write scheduling
    
    [ Upstream commit 954998b60caa8f2a3bf3abe490de6f08d283687a ]
    
    If we fail to schedule a request for transmission, there are 2
    possibilities:
    1) Either we hit a fatal error, and we just want to drop the remaining
       requests on the floor.
    2) We were asked to try again, in which case we should allow the
       outstanding RPC calls to complete, so that we can recoalesce requests
       and try again.
    
    Fixes: d600ad1f2bdb ("NFS41: pop some layoutget errors to application")
    Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
    Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 47d892a1d363d..ee88f0a6e7b81 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -528,10 +528,9 @@ nfs_direct_write_scan_commit_list(struct inode *inode,
 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 {
 	struct nfs_pageio_descriptor desc;
-	struct nfs_page *req, *tmp;
+	struct nfs_page *req;
 	LIST_HEAD(reqs);
 	struct nfs_commit_info cinfo;
-	LIST_HEAD(failed);
 
 	nfs_init_cinfo_from_dreq(&cinfo, dreq);
 	nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
@@ -549,27 +548,36 @@ static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 			      &nfs_direct_write_completion_ops);
 	desc.pg_dreq = dreq;
 
-	list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
+	while (!list_empty(&reqs)) {
+		req = nfs_list_entry(reqs.next);
 		/* Bump the transmission count */
 		req->wb_nio++;
 		if (!nfs_pageio_add_request(&desc, req)) {
-			nfs_list_move_request(req, &failed);
 			spin_lock(&cinfo.inode->i_lock);
-			dreq->flags = 0;
-			if (desc.pg_error < 0)
+			if (dreq->error < 0) {
+				desc.pg_error = dreq->error;
+			} else if (desc.pg_error != -EAGAIN) {
+				dreq->flags = 0;
+				if (!desc.pg_error)
+					desc.pg_error = -EIO;
 				dreq->error = desc.pg_error;
-			else
-				dreq->error = -EIO;
+			} else
+				dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 			spin_unlock(&cinfo.inode->i_lock);
+			break;
 		}
 		nfs_release_request(req);
 	}
 	nfs_pageio_complete(&desc);
 
-	while (!list_empty(&failed)) {
-		req = nfs_list_entry(failed.next);
+	while (!list_empty(&reqs)) {
+		req = nfs_list_entry(reqs.next);
 		nfs_list_remove_request(req);
 		nfs_unlock_and_release_request(req);
+		if (desc.pg_error == -EAGAIN)
+			nfs_mark_request_commit(req, NULL, &cinfo, 0);
+		else
+			nfs_release_request(req);
 	}
 
 	if (put_dreq(dreq))
@@ -794,9 +802,11 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 {
 	struct nfs_pageio_descriptor desc;
 	struct inode *inode = dreq->inode;
+	struct nfs_commit_info cinfo;
 	ssize_t result = 0;
 	size_t requested_bytes = 0;
 	size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
+	bool defer = false;
 
 	trace_nfs_direct_write_schedule_iovec(dreq);
 
@@ -837,17 +847,37 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 				break;
 			}
 
-			nfs_lock_request(req);
-			if (!nfs_pageio_add_request(&desc, req)) {
-				result = desc.pg_error;
-				nfs_unlock_and_release_request(req);
-				break;
-			}
 			pgbase = 0;
 			bytes -= req_len;
 			requested_bytes += req_len;
 			pos += req_len;
 			dreq->bytes_left -= req_len;
+
+			if (defer) {
+				nfs_mark_request_commit(req, NULL, &cinfo, 0);
+				continue;
+			}
+
+			nfs_lock_request(req);
+			if (nfs_pageio_add_request(&desc, req))
+				continue;
+
+			/* Exit on hard errors */
+			if (desc.pg_error < 0 && desc.pg_error != -EAGAIN) {
+				result = desc.pg_error;
+				nfs_unlock_and_release_request(req);
+				break;
+			}
+
+			/* If the error is soft, defer remaining requests */
+			nfs_init_cinfo_from_dreq(&cinfo, dreq);
+			spin_lock(&cinfo.inode->i_lock);
+			dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+			spin_unlock(&cinfo.inode->i_lock);
+			nfs_unlock_request(req);
+			nfs_mark_request_commit(req, NULL, &cinfo, 0);
+			desc.pg_error = 0;
+			defer = true;
 		}
 		nfs_direct_release_pages(pagevec, npages);
 		kvfree(pagevec);