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 v6 2/9] iversion: clarify when the i_version counter must be updated
Date: Fri, 30 Sep 2022 07:18:33 -0400 [thread overview]
Message-ID: <20220930111840.10695-3-jlayton@kernel.org> (raw)
In-Reply-To: <20220930111840.10695-1-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 6755d8b4f20b..9925cac1fa94 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:[~2022-09-30 11:27 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-30 11:18 [PATCH v6 0/9] vfs/nfsd: clean up handling of i_version counter Jeff Layton
2022-09-30 11:18 ` [PATCH v6 1/9] iversion: move inode_query_iversion to libfs.c Jeff Layton
2022-10-03 23:05 ` NeilBrown
2022-09-30 11:18 ` Jeff Layton [this message]
2022-10-03 23:10 ` [PATCH v6 2/9] iversion: clarify when the i_version counter must be updated NeilBrown
2022-10-04 9:53 ` Jeff Layton
2022-09-30 11:18 ` [PATCH v6 3/9] vfs: plumb i_version handling into struct kstat Jeff Layton
2022-10-03 23:14 ` NeilBrown
2022-09-30 11:18 ` [PATCH v6 4/9] nfs: report the inode version in getattr if requested Jeff Layton
2022-10-03 23:29 ` NeilBrown
2022-10-04 9:43 ` Jeff Layton
2022-10-04 22:27 ` NeilBrown
2022-09-30 11:18 ` [PATCH v6 5/9] ceph: " Jeff Layton
2022-09-30 11:18 ` [PATCH v6 6/9] nfsd: use the getattr operation to fetch i_version Jeff Layton
2022-09-30 14:34 ` Chuck Lever III
2022-09-30 22:32 ` Dave Chinner
2022-10-03 23:39 ` NeilBrown
2022-10-05 10:06 ` Jeff Layton
2022-10-05 13:33 ` Chuck Lever III
2022-10-05 13:34 ` Trond Myklebust
2022-10-05 13:57 ` Jeff Layton
2022-10-05 21:14 ` NeilBrown
2022-10-06 11:15 ` Jeff Layton
2022-10-06 21:17 ` Dave Chinner
2022-09-30 11:18 ` [PATCH v6 7/9] vfs: expose STATX_VERSION to userland Jeff Layton
2022-10-03 23:42 ` NeilBrown
2022-10-05 10:08 ` Jeff Layton
2022-09-30 11:18 ` [PATCH v6 8/9] vfs: update times after copying data in __generic_file_write_iter Jeff Layton
2022-10-01 20:39 ` kernel test robot
2022-10-01 21:00 ` kernel test robot
2022-10-02 7:08 ` Amir Goldstein
2022-10-03 13:01 ` Jeff Layton
2022-10-03 13:52 ` Amir Goldstein
2022-10-03 22:56 ` NeilBrown
2022-10-05 16:40 ` Jeff Layton
2022-10-05 21:40 ` NeilBrown
2022-09-30 11:18 ` [PATCH v6 9/9] ext4: update times after I/O in write codepaths Jeff Layton
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