git: e5d000b33383 - stable/13 - nfsd: Make loop calling VOP_ALLOCATE() iterate until done

[Rick Macklem]

The branch stable/13 has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=e5d000b333830ad2795ec3a265b3d2f499b4065c

commit e5d000b333830ad2795ec3a265b3d2f499b4065c
Author:     Rick Macklem <rmacklem at FreeBSD.org>
AuthorDate: 2021-08-29 23:46:27 +0000
Commit:     Rick Macklem <rmacklem at FreeBSD.org>
CommitDate: 2021-09-15 23:01:41 +0000

    nfsd: Make loop calling VOP_ALLOCATE() iterate until done
    
    The NFSv4.2 Deallocate operation loops on VOP_DEALLOCATE()
    while progress is being made (remaining length decreasing).
    This patch changes the loop on VOP_ALLOCATE() for the NFSv4.2
    Allocate operation do the same, instead of stopping after
    an arbitrary 20 iterations.
    
    (cherry picked from commit 13914e51eb8de6fe9f627c9c1d48c09880b2607e)
---
 sys/fs/nfsserver/nfs_nfsdport.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/sys/fs/nfsserver/nfs_nfsdport.c b/sys/fs/nfsserver/nfs_nfsdport.c
index efe9aac7a136..f48e57e449c9 100644
--- a/sys/fs/nfsserver/nfs_nfsdport.c
+++ b/sys/fs/nfsserver/nfs_nfsdport.c
@@ -6399,7 +6399,8 @@ int
 nfsvno_allocate(struct vnode *vp, off_t off, off_t len, struct ucred *cred,
     NFSPROC_T *p)
 {
-	int error, trycnt;
+	int error;
+	off_t olen;
 
 	ASSERT_VOP_ELOCKED(vp, "nfsvno_allocate vp");
 	/*
@@ -6410,15 +6411,17 @@ nfsvno_allocate(struct vnode *vp, off_t off, off_t len, struct ucred *cred,
 	    NULL, NULL, NULL, NULL, &len, 0, NULL);
 	if (error != ENOENT)
 		return (error);
-	error = 0;
 
 	/*
-	 * Do the actual VOP_ALLOCATE(), looping a reasonable number of
-	 * times to achieve completion.
+	 * Do the actual VOP_ALLOCATE(), looping so long as
+	 * progress is being made, to achieve completion.
 	 */
-	trycnt = 0;
-	while (error == 0 && len > 0 && trycnt++ < 20)
+	do {
+		olen = len;
 		error = VOP_ALLOCATE(vp, &off, &len);
+		if (error == 0 && len > 0 && olen > len)
+			maybe_yield();
+	} while (error == 0 && len > 0 && olen > len);
 	if (error == 0 && len > 0)
 		error = NFSERR_IO;
 	NFSEXITCODE(error);