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Subject: [PATCH 02/67] vfs: Provide S_KERNEL_FILE inode flag
From:   David Howells <dhowells@redhat.com>
To:     linux-cachefs@redhat.com
Cc:     dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Steve French <sfrench@samba.org>,
        Dominique Martinet <asmadeus@codewreck.org>,
        Jeff Layton <jlayton@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Omar Sandoval <osandov@osandov.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
        linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
        v9fs-developer@lists.sourceforge.net,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Mon, 18 Oct 2021 15:50:52 +0100
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Provide an S_KERNEL_FILE inode flag that a kernel service, e.g. cachefiles,
can set to ward off other kernel services and drivers (including itself)
from using files it is actively using.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 include/linux/fs.h |    1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index e7a633353fd2..197493507744 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2250,6 +2250,7 @@ struct super_operations {
 #define S_ENCRYPTED	(1 << 14) /* Encrypted file (using fs/crypto/) */
 #define S_CASEFOLD	(1 << 15) /* Casefolded file */
 #define S_VERITY	(1 << 16) /* Verity file (using fs/verity/) */
+#define S_KERNEL_FILE	(1 << 17) /* File is in use by the kernel (eg. fs/cachefiles) */
 
 /*
  * Note that nosuid etc flags are inode-specific: setting some file-system