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authorJeff Layton <jlayton@redhat.com>2016-12-04 15:29:46 +0100
committerJeff Layton <jlayton@kernel.org>2023-01-26 13:00:06 +0100
commita1175d6b1bdaf4f74eda47ab18eb44194f9cb796 (patch)
tree119118d44cd9bb0ad0b9ac5407b91dac9ec3d3da /fs/stat.c
parentfs: clarify when the i_version counter must be updated (diff)
downloadlinux-a1175d6b1bdaf4f74eda47ab18eb44194f9cb796.tar.xz
linux-a1175d6b1bdaf4f74eda47ab18eb44194f9cb796.zip
vfs: plumb i_version handling into struct kstat
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@suse.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jeff Layton <jlayton@kernel.org>
Diffstat (limited to 'fs/stat.c')
-rw-r--r--fs/stat.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/fs/stat.c b/fs/stat.c
index d6cc74ca8486..f43afe0081fe 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -18,6 +18,7 @@
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/compat.h>
+#include <linux/iversion.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
@@ -122,6 +123,11 @@ 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);
+ }
+
mnt_userns = mnt_user_ns(path->mnt);
if (inode->i_op->getattr)
return inode->i_op->getattr(mnt_userns, path, stat,
@@ -602,9 +608,11 @@ 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);
@@ -643,6 +651,11 @@ int do_statx(int dfd, struct filename *filename, unsigned int 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;