This is a note to let you know that I've just added the patch titled
vfs: plumb i_version handling into struct kstat
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
vfs-plumb-i_version-handling-into-struct-kstat.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c271cde72b2e037c3e9955790d124d763030abe3
Author: Jeff Layton <jlayton@xxxxxxxxxx>
Date: Sun Dec 4 09:29:46 2016 -0500
vfs: plumb i_version handling into struct kstat
[ Upstream commit a1175d6b1bdaf4f74eda47ab18eb44194f9cb796 ]
The NFS server has a lot of special handling for different types of
change attribute access, depending on the underlying filesystem. In
most cases, it's doing a getattr anyway and then fetching that value
after the fact.
Rather that do that, add a new STATX_CHANGE_COOKIE flag that is a
kernel-only symbol (for now). If requested and getattr can implement it,
it can fill out this field. For IS_I_VERSION inodes, add a generic
implementation in vfs_getattr_nosec. Take care to mask
STATX_CHANGE_COOKIE off in requests from userland and in the result
mask.
Since not all filesystems can give the same guarantees of monotonicity,
claim a STATX_ATTR_CHANGE_MONOTONIC flag that filesystems can set to
indicate that they offer an i_version value that can never go backward.
Eventually if we decide to make the i_version available to userland, we
can just designate a field for it in struct statx, and move the
STATX_CHANGE_COOKIE definition to the uapi header.
Reviewed-by: NeilBrown <neilb@xxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Stable-dep-of: db1d1e8b9867 ("IMA: use vfs_getattr_nosec to get the i_version")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/stat.c b/fs/stat.c
index 04550c0ba5407..3ac06528ad4cf 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -17,6 +17,7 @@
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/compat.h>
+#include <linux/iversion.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
@@ -91,6 +92,11 @@ int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
stat->attributes_mask |= (STATX_ATTR_AUTOMOUNT |
STATX_ATTR_DAX);
+ if ((request_mask & STATX_CHANGE_COOKIE) && IS_I_VERSION(inode)) {
+ stat->result_mask |= STATX_CHANGE_COOKIE;
+ stat->change_cookie = inode_query_iversion(inode);
+ }
+
if (inode->i_op->getattr)
return inode->i_op->getattr(path, stat, request_mask,
query_flags);
@@ -545,9 +551,11 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
memset(&tmp, 0, sizeof(tmp));
- tmp.stx_mask = stat->result_mask;
+ /* STATX_CHANGE_COOKIE is kernel-only for now */
+ tmp.stx_mask = stat->result_mask & ~STATX_CHANGE_COOKIE;
tmp.stx_blksize = stat->blksize;
- tmp.stx_attributes = stat->attributes;
+ /* STATX_ATTR_CHANGE_MONOTONIC is kernel-only for now */
+ tmp.stx_attributes = stat->attributes & ~STATX_ATTR_CHANGE_MONOTONIC;
tmp.stx_nlink = stat->nlink;
tmp.stx_uid = from_kuid_munged(current_user_ns(), stat->uid);
tmp.stx_gid = from_kgid_munged(current_user_ns(), stat->gid);
@@ -584,6 +592,11 @@ int do_statx(int dfd, const char __user *filename, unsigned flags,
if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
return -EINVAL;
+ /* STATX_CHANGE_COOKIE is kernel-only for now. Ignore requests
+ * from userland.
+ */
+ mask &= ~STATX_CHANGE_COOKIE;
+
error = vfs_statx(dfd, filename, flags, &stat, mask);
if (error)
return error;
diff --git a/include/linux/stat.h b/include/linux/stat.h
index fff27e6038141..cd64f44642b1a 100644
--- a/include/linux/stat.h
+++ b/include/linux/stat.h
@@ -46,6 +46,15 @@ struct kstat {
struct timespec64 btime; /* File creation time */
u64 blocks;
u64 mnt_id;
+ u64 change_cookie;
};
+/* These definitions are internal to the kernel for now. Mainly used by nfsd. */
+
+/* mask values */
+#define STATX_CHANGE_COOKIE 0x40000000U /* Want/got stx_change_attr */
+
+/* file attribute values */
+#define STATX_ATTR_CHANGE_MONOTONIC 0x8000000000000000ULL /* version monotonically increases */
+
#endif
