NFS: O_DIRECT writes must check and adjust the file length

JIRA: https://issues.redhat.com/browse/RHEL-87767

commit fcf857e
Author: Trond Myklebust <trond.myklebust@hammerspace.com>
Date:   Sat Feb 1 14:59:02 2025 -0500

    NFS: O_DIRECT writes must check and adjust the file length

    While it is uncommon for delegations to be held while O_DIRECT writes
    are in progress, it is possible. The xfstests generic/647 and
    generic/729 both end up triggering that state, and end up failing due to
    the fact that the file size is not adjusted.

    Reported-by: Chuck Lever <chuck.lever@oracle.com>
    Link: https://bugzilla.kernel.org/show_bug.cgi?id=219738
    Cc: stable@vger.kernel.org
    Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
    Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>

Author: bcodding-rh

fs/nfs/direct.c

@@ -130,6 +130,20 @@ static void nfs_direct_truncate_request(struct nfs_direct_req *dreq,
 		dreq->count = req_start;
 }
 
+static void nfs_direct_file_adjust_size_locked(struct inode *inode,
+					       loff_t offset, size_t count)
+{
+	loff_t newsize = offset + (loff_t)count;
+	loff_t oldsize = i_size_read(inode);
+
+	if (newsize > oldsize) {
+		i_size_write(inode, newsize);
+		NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
+		trace_nfs_size_grow(inode, newsize);
+		nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
+	}
+}
+
 /**
  * nfs_swap_rw - NFS address space operation for swap I/O
  * @iocb: target I/O control block
@@ -732,6 +746,7 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
 	struct nfs_direct_req *dreq = hdr->dreq;
 	struct nfs_commit_info cinfo;
 	struct nfs_page *req = nfs_list_entry(hdr->pages.next);
+	struct inode *inode = dreq->inode;
 	int flags = NFS_ODIRECT_DONE;
 
 	trace_nfs_direct_write_completion(dreq);
@@ -753,6 +768,10 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
 	}
 	spin_unlock(&dreq->lock);
 
+	spin_lock(&inode->i_lock);
+	nfs_direct_file_adjust_size_locked(inode, dreq->io_start, dreq->count);
+	spin_unlock(&inode->i_lock);
+
 	while (!list_empty(&hdr->pages)) {
 
 		req = nfs_list_entry(hdr->pages.next);