From: Jeff Layton <jlayton@kernel.org>
To: tytso@mit.edu, adilger.kernel@dilger.ca, djwong@kernel.org,
david@fromorbit.com, trondmy@hammerspace.com, neilb@suse.de,
viro@zeniv.linux.org.uk, zohar@linux.ibm.com, xiubli@redhat.com,
chuck.lever@oracle.com, lczerner@redhat.com, jack@suse.cz,
bfields@fieldses.org, brauner@kernel.org, fweimer@redhat.com
Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org,
linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org,
linux-xfs@vger.kernel.org, Colin Walters <walters@verbum.org>
Subject: [PATCH v5 1/8] iversion: clarify when the i_version counter must be updated
Date: Thu, 8 Sep 2022 13:24:41 -0400 [thread overview]
Message-ID: <20220908172448.208585-2-jlayton@kernel.org> (raw)
In-Reply-To: <20220908172448.208585-1-jlayton@kernel.org>
The i_version field in the kernel has had different semantics over
the decades, but NFSv4 has certain expectations. Update the comments
in iversion.h to describe when the i_version must change.
Cc: Colin Walters <walters@verbum.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Trond Myklebust <trondmy@hammerspace.com>
Cc: Dave Chinner <david@fromorbit.com>
Link: https://lore.kernel.org/linux-xfs/166086932784.5425.17134712694961326033@noble.neil.brown.name/#t
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
include/linux/iversion.h | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/include/linux/iversion.h b/include/linux/iversion.h
index 3bfebde5a1a6..0555a3851dbf 100644
--- a/include/linux/iversion.h
+++ b/include/linux/iversion.h
@@ -9,8 +9,14 @@
* ---------------------------
* The change attribute (i_version) is mandated by NFSv4 and is mostly for
* knfsd, but is also used for other purposes (e.g. IMA). The i_version must
- * appear different to observers if there was a change to the inode's data or
- * metadata since it was last queried.
+ * appear larger to observers if there was an explicit change to the inode's
+ * data or metadata since it was last queried.
+ *
+ * An explicit change is one that would ordinarily result in a change to the
+ * inode status change time (aka ctime). i_version must appear to change, even
+ * if the ctime does not (since the whole point is to avoid missing updates due
+ * to timestamp granularity). If POSIX mandates that the ctime must change due
+ * to an operation, then the i_version counter must be incremented as well.
*
* Observers see the i_version as a 64-bit number that never decreases. If it
* remains the same since it was last checked, then nothing has changed in the
--
2.37.3
next prev parent reply other threads:[~2022-09-08 17:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-08 17:24 [PATCH v5 0/8] vfs/nfsd: clean up handling of the i_version counter Jeff Layton
2022-09-08 17:24 ` Jeff Layton [this message]
2022-09-08 17:24 ` [PATCH v5 2/8] ext4: fix i_version handling in ext4 Jeff Layton
2022-09-30 1:22 ` Theodore Ts'o
2022-09-08 17:24 ` [PATCH v5 3/8] ext4: unconditionally enable the i_version counter Jeff Layton
2022-09-08 17:24 ` [PATCH v5 4/8] vfs: plumb i_version handling into struct kstat Jeff Layton
2022-09-08 17:24 ` [PATCH v5 5/8] nfs: report the inode version in getattr if requested Jeff Layton
2022-09-08 17:24 ` [PATCH v5 6/8] ceph: " Jeff Layton
2022-09-08 17:24 ` [PATCH v5 7/8] nfsd: use the getattr operation to fetch i_version Jeff Layton
2022-09-08 17:24 ` [RFC PATCH v5 8/8] nfsd: take inode_lock when querying for NFSv4 GETATTR Jeff Layton
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