git: 74654ba3b1b3 - main - chflags: Add a new UF_DONTCACHE flag

The branch main has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=74654ba3b1b3bcf6ba8870a54310accbb6adbf0b

commit 74654ba3b1b3bcf6ba8870a54310accbb6adbf0b
Author:     Rick Macklem <rmacklem@FreeBSD.org>
AuthorDate: 2026-07-12 22:45:28 +0000
Commit:     Rick Macklem <rmacklem@FreeBSD.org>
CommitDate: 2026-07-12 22:45:28 +0000

    chflags: Add a new UF_DONTCACHE flag
    
    This internet draft (which is close to being an RFC)
    specifies a new NFSv4.2 attribute which tells the NFSv4.2
    client to not cache file data. (Similar to O_DIRECT, but
    triggered by this attribute set on the file on the NFSv4.2
    server and not by the application's open(2).)
    
    https://datatracker.ietf.org/doc/draft-ietf-nfsv4-uncacheable-files/
    
    This patch adds a new chflags(1) flag called UF_DONTCACHE to
    implement this.
    
    Patches for NFS and ZFS will be done separately.
    
    Reviewed by:    kib
    MFC after:      2 weeks
    Differential Revision:  https://reviews.freebsd.org/D58181
---
 lib/libc/gen/strtofflags.c | 4 +++-
 sys/fs/tmpfs/tmpfs_subr.c  | 2 +-
 sys/sys/stat.h             | 1 +
 sys/ufs/ufs/ufs_vnops.c    | 2 +-
 4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/lib/libc/gen/strtofflags.c b/lib/libc/gen/strtofflags.c
index 73b4db54ccdd..ca12401c37e5 100644
--- a/lib/libc/gen/strtofflags.c
+++ b/lib/libc/gen/strtofflags.c
@@ -80,7 +80,9 @@ static struct {
 	{ "nosparse",		0, UF_SPARSE	},
 	{ "nousparse",		0, UF_SPARSE	},
 	{ "nosystem",		0, UF_SYSTEM	},
-	{ "nousystem",		0, UF_SYSTEM	}
+	{ "nousystem",		0, UF_SYSTEM	},
+	{ "nodontcache",	0, UF_DONTCACHE	},
+	{ "noudontcache",	0, UF_DONTCACHE	}
 };
 #define nmappings	(sizeof(mapping) / sizeof(mapping[0]))
 
diff --git a/sys/fs/tmpfs/tmpfs_subr.c b/sys/fs/tmpfs/tmpfs_subr.c
index dd281d18d87d..c9a9a3114fb3 100644
--- a/sys/fs/tmpfs/tmpfs_subr.c
+++ b/sys/fs/tmpfs/tmpfs_subr.c
@@ -2042,7 +2042,7 @@ tmpfs_chflags(struct vnode *vp, u_long flags, struct ucred *cred,
 	if ((flags & ~(SF_APPEND | SF_ARCHIVED | SF_IMMUTABLE | SF_NOUNLINK |
 	    UF_APPEND | UF_ARCHIVE | UF_HIDDEN | UF_IMMUTABLE | UF_NODUMP |
 	    UF_NOUNLINK | UF_OFFLINE | UF_OPAQUE | UF_READONLY | UF_REPARSE |
-	    UF_SPARSE | UF_SYSTEM)) != 0)
+	    UF_SPARSE | UF_SYSTEM | UF_DONTCACHE)) != 0)
 		return (EOPNOTSUPP);
 
 	/* Disallow this operation if the file system is mounted read-only. */
diff --git a/sys/sys/stat.h b/sys/sys/stat.h
index 0c58838094ed..457ec99365d2 100644
--- a/sys/sys/stat.h
+++ b/sys/sys/stat.h
@@ -327,6 +327,7 @@ struct nstat {
 #define	UF_REPARSE	0x00000400	/* Windows reparse point file bit */
 #define	UF_ARCHIVE	0x00000800	/* file needs to be archived */
 #define	UF_READONLY	0x00001000	/* Windows readonly file bit */
+#define	UF_DONTCACHE	0x00002000	/* don't cache file data (NFSv4) */
 /* This is the same as the MacOS X definition of UF_HIDDEN. */
 #define	UF_HIDDEN	0x00008000	/* file is hidden */
 
diff --git a/sys/ufs/ufs/ufs_vnops.c b/sys/ufs/ufs/ufs_vnops.c
index 1d04e1b2785f..762b5bb5b5ec 100644
--- a/sys/ufs/ufs/ufs_vnops.c
+++ b/sys/ufs/ufs/ufs_vnops.c
@@ -667,7 +667,7 @@ ufs_setattr(
 		    SF_NOUNLINK | SF_SNAPSHOT | UF_APPEND | UF_ARCHIVE |
 		    UF_HIDDEN | UF_IMMUTABLE | UF_NODUMP | UF_NOUNLINK |
 		    UF_OFFLINE | UF_OPAQUE | UF_READONLY | UF_REPARSE |
-		    UF_SPARSE | UF_SYSTEM)) != 0)
+		    UF_SPARSE | UF_SYSTEM | UF_DONTCACHE)) != 0)
 			return (EOPNOTSUPP);
 		if (vp->v_mount->mnt_flag & MNT_RDONLY)
 			return (EROFS);