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-rw-r--r--fs/ceph/inode.c16
-rw-r--r--fs/libfs.c36
-rw-r--r--fs/nfs/export.c7
-rw-r--r--fs/nfs/inode.c16
-rw-r--r--fs/nfsd/nfs4xdr.c4
-rw-r--r--fs/nfsd/nfsfh.c42
-rw-r--r--fs/nfsd/nfsfh.h29
-rw-r--r--fs/nfsd/vfs.h7
-rw-r--r--fs/stat.c17
-rw-r--r--include/linux/exportfs.h1
-rw-r--r--include/linux/iversion.h60
-rw-r--r--include/linux/stat.h9
12 files changed, 157 insertions, 87 deletions
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 23d05ec87fcc..e22e631cb115 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -2417,10 +2417,10 @@ static int statx_to_caps(u32 want, umode_t mode)
{
int mask = 0;
- if (want & (STATX_MODE|STATX_UID|STATX_GID|STATX_CTIME|STATX_BTIME))
+ if (want & (STATX_MODE|STATX_UID|STATX_GID|STATX_CTIME|STATX_BTIME|STATX_CHANGE_COOKIE))
mask |= CEPH_CAP_AUTH_SHARED;
- if (want & (STATX_NLINK|STATX_CTIME)) {
+ if (want & (STATX_NLINK|STATX_CTIME|STATX_CHANGE_COOKIE)) {
/*
* The link count for directories depends on inode->i_subdirs,
* and that is only updated when Fs caps are held.
@@ -2431,11 +2431,10 @@ static int statx_to_caps(u32 want, umode_t mode)
mask |= CEPH_CAP_LINK_SHARED;
}
- if (want & (STATX_ATIME|STATX_MTIME|STATX_CTIME|STATX_SIZE|
- STATX_BLOCKS))
+ if (want & (STATX_ATIME|STATX_MTIME|STATX_CTIME|STATX_SIZE|STATX_BLOCKS|STATX_CHANGE_COOKIE))
mask |= CEPH_CAP_FILE_SHARED;
- if (want & (STATX_CTIME))
+ if (want & (STATX_CTIME|STATX_CHANGE_COOKIE))
mask |= CEPH_CAP_XATTR_SHARED;
return mask;
@@ -2478,6 +2477,11 @@ int ceph_getattr(struct user_namespace *mnt_userns, const struct path *path,
valid_mask |= STATX_BTIME;
}
+ if (request_mask & STATX_CHANGE_COOKIE) {
+ stat->change_cookie = inode_peek_iversion_raw(inode);
+ valid_mask |= STATX_CHANGE_COOKIE;
+ }
+
if (ceph_snap(inode) == CEPH_NOSNAP)
stat->dev = sb->s_dev;
else
@@ -2519,6 +2523,8 @@ int ceph_getattr(struct user_namespace *mnt_userns, const struct path *path,
stat->nlink = 1 + 1 + ci->i_subdirs;
}
+ stat->attributes_mask |= STATX_ATTR_CHANGE_MONOTONIC;
+ stat->attributes |= STATX_ATTR_CHANGE_MONOTONIC;
stat->result_mask = request_mask & valid_mask;
return err;
}
diff --git a/fs/libfs.c b/fs/libfs.c
index aada4e7c8713..17ecc47696e1 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1582,3 +1582,39 @@ bool inode_maybe_inc_iversion(struct inode *inode, bool force)
return true;
}
EXPORT_SYMBOL(inode_maybe_inc_iversion);
+
+/**
+ * inode_query_iversion - read i_version for later use
+ * @inode: inode from which i_version should be read
+ *
+ * Read the inode i_version counter. This should be used by callers that wish
+ * to store the returned i_version for later comparison. This will guarantee
+ * that a later query of the i_version will result in a different value if
+ * anything has changed.
+ *
+ * In this implementation, we fetch the current value, set the QUERIED flag and
+ * then try to swap it into place with a cmpxchg, if it wasn't already set. If
+ * that fails, we try again with the newly fetched value from the cmpxchg.
+ */
+u64 inode_query_iversion(struct inode *inode)
+{
+ u64 cur, new;
+
+ cur = inode_peek_iversion_raw(inode);
+ do {
+ /* If flag is already set, then no need to swap */
+ if (cur & I_VERSION_QUERIED) {
+ /*
+ * This barrier (and the implicit barrier in the
+ * cmpxchg below) pairs with the barrier in
+ * inode_maybe_inc_iversion().
+ */
+ smp_mb();
+ break;
+ }
+
+ new = cur | I_VERSION_QUERIED;
+ } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
+ return cur >> I_VERSION_QUERIED_SHIFT;
+}
+EXPORT_SYMBOL(inode_query_iversion);
diff --git a/fs/nfs/export.c b/fs/nfs/export.c
index 01596f2d0a1e..1a9d5aa51dfb 100644
--- a/fs/nfs/export.c
+++ b/fs/nfs/export.c
@@ -145,17 +145,10 @@ out:
return parent;
}
-static u64 nfs_fetch_iversion(struct inode *inode)
-{
- nfs_revalidate_inode(inode, NFS_INO_INVALID_CHANGE);
- return inode_peek_iversion_raw(inode);
-}
-
const struct export_operations nfs_export_ops = {
.encode_fh = nfs_encode_fh,
.fh_to_dentry = nfs_fh_to_dentry,
.get_parent = nfs_get_parent,
- .fetch_iversion = nfs_fetch_iversion,
.flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK|
EXPORT_OP_CLOSE_BEFORE_UNLINK|EXPORT_OP_REMOTE_FS|
EXPORT_OP_NOATOMIC_ATTR,
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index e98ee7599eeb..756ad4fa6f2a 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -825,6 +825,8 @@ static u32 nfs_get_valid_attrmask(struct inode *inode)
reply_mask |= STATX_UID | STATX_GID;
if (!(cache_validity & NFS_INO_INVALID_BLOCKS))
reply_mask |= STATX_BLOCKS;
+ if (!(cache_validity & NFS_INO_INVALID_CHANGE))
+ reply_mask |= STATX_CHANGE_COOKIE;
return reply_mask;
}
@@ -843,7 +845,8 @@ int nfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
request_mask &= STATX_TYPE | STATX_MODE | STATX_NLINK | STATX_UID |
STATX_GID | STATX_ATIME | STATX_MTIME | STATX_CTIME |
- STATX_INO | STATX_SIZE | STATX_BLOCKS;
+ STATX_INO | STATX_SIZE | STATX_BLOCKS | STATX_BTIME |
+ STATX_CHANGE_COOKIE;
if ((query_flags & AT_STATX_DONT_SYNC) && !force_sync) {
if (readdirplus_enabled)
@@ -851,8 +854,8 @@ int nfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
goto out_no_revalidate;
}
- /* Flush out writes to the server in order to update c/mtime. */
- if ((request_mask & (STATX_CTIME | STATX_MTIME)) &&
+ /* Flush out writes to the server in order to update c/mtime/version. */
+ if ((request_mask & (STATX_CTIME | STATX_MTIME | STATX_CHANGE_COOKIE)) &&
S_ISREG(inode->i_mode))
filemap_write_and_wait(inode->i_mapping);
@@ -872,7 +875,8 @@ int nfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
/* Is the user requesting attributes that might need revalidation? */
if (!(request_mask & (STATX_MODE|STATX_NLINK|STATX_ATIME|STATX_CTIME|
STATX_MTIME|STATX_UID|STATX_GID|
- STATX_SIZE|STATX_BLOCKS)))
+ STATX_SIZE|STATX_BLOCKS|
+ STATX_CHANGE_COOKIE)))
goto out_no_revalidate;
/* Check whether the cached attributes are stale */
@@ -910,6 +914,10 @@ out_no_revalidate:
generic_fillattr(&init_user_ns, inode, stat);
stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
+ stat->change_cookie = inode_peek_iversion_raw(inode);
+ stat->attributes_mask |= STATX_ATTR_CHANGE_MONOTONIC;
+ if (server->change_attr_type != NFS4_CHANGE_TYPE_IS_UNDEFINED)
+ stat->attributes |= STATX_ATTR_CHANGE_MONOTONIC;
if (S_ISDIR(inode->i_mode))
stat->blksize = NFS_SERVER(inode)->dtsize;
out:
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 97edb32be77f..e12e5a4ad502 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2965,7 +2965,9 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
goto out;
}
- err = vfs_getattr(&path, &stat, STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
+ err = vfs_getattr(&path, &stat,
+ STATX_BASIC_STATS | STATX_BTIME | STATX_CHANGE_COOKIE,
+ AT_STATX_SYNC_AS_STAT);
if (err)
goto out_nfserr;
if (!(stat.result_mask & STATX_BTIME))
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index 8c52b6c9d31a..76ea268dc420 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -628,6 +628,10 @@ void fh_fill_pre_attrs(struct svc_fh *fhp)
stat.mtime = inode->i_mtime;
stat.ctime = inode->i_ctime;
stat.size = inode->i_size;
+ if (v4 && IS_I_VERSION(inode)) {
+ stat.change_cookie = inode_query_iversion(inode);
+ stat.result_mask |= STATX_CHANGE_COOKIE;
+ }
}
if (v4)
fhp->fh_pre_change = nfsd4_change_attribute(&stat, inode);
@@ -659,6 +663,10 @@ void fh_fill_post_attrs(struct svc_fh *fhp)
if (err) {
fhp->fh_post_saved = false;
fhp->fh_post_attr.ctime = inode->i_ctime;
+ if (v4 && IS_I_VERSION(inode)) {
+ fhp->fh_post_attr.change_cookie = inode_query_iversion(inode);
+ fhp->fh_post_attr.result_mask |= STATX_CHANGE_COOKIE;
+ }
} else
fhp->fh_post_saved = true;
if (v4)
@@ -748,3 +756,37 @@ enum fsid_source fsid_source(const struct svc_fh *fhp)
return FSIDSOURCE_UUID;
return FSIDSOURCE_DEV;
}
+
+/*
+ * We could use i_version alone as the change attribute. However, i_version
+ * can go backwards on a regular file after an unclean shutdown. On its own
+ * that doesn't necessarily cause a problem, but if i_version goes backwards
+ * and then is incremented again it could reuse a value that was previously
+ * used before boot, and a client who queried the two values might incorrectly
+ * assume nothing changed.
+ *
+ * By using both ctime and the i_version counter we guarantee that as long as
+ * time doesn't go backwards we never reuse an old value. If the filesystem
+ * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not
+ * needed.
+ *
+ * We only need to do this for regular files as well. For directories, we
+ * assume that the new change attr is always logged to stable storage in some
+ * fashion before the results can be seen.
+ */
+u64 nfsd4_change_attribute(struct kstat *stat, struct inode *inode)
+{
+ u64 chattr;
+
+ if (stat->result_mask & STATX_CHANGE_COOKIE) {
+ chattr = stat->change_cookie;
+ if (S_ISREG(inode->i_mode) &&
+ !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) {
+ chattr += (u64)stat->ctime.tv_sec << 30;
+ chattr += stat->ctime.tv_nsec;
+ }
+ } else {
+ chattr = time_to_chattr(&stat->ctime);
+ }
+ return chattr;
+}
diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h
index 513e028b0bbe..4e0ecf0ae2cf 100644
--- a/fs/nfsd/nfsfh.h
+++ b/fs/nfsd/nfsfh.h
@@ -293,34 +293,7 @@ static inline void fh_clear_pre_post_attrs(struct svc_fh *fhp)
fhp->fh_pre_saved = false;
}
-/*
- * We could use i_version alone as the change attribute. However,
- * i_version can go backwards after a reboot. On its own that doesn't
- * necessarily cause a problem, but if i_version goes backwards and then
- * is incremented again it could reuse a value that was previously used
- * before boot, and a client who queried the two values might
- * incorrectly assume nothing changed.
- *
- * By using both ctime and the i_version counter we guarantee that as
- * long as time doesn't go backwards we never reuse an old value.
- */
-static inline u64 nfsd4_change_attribute(struct kstat *stat,
- struct inode *inode)
-{
- if (inode->i_sb->s_export_op->fetch_iversion)
- return inode->i_sb->s_export_op->fetch_iversion(inode);
- else if (IS_I_VERSION(inode)) {
- u64 chattr;
-
- chattr = stat->ctime.tv_sec;
- chattr <<= 30;
- chattr += stat->ctime.tv_nsec;
- chattr += inode_query_iversion(inode);
- return chattr;
- } else
- return time_to_chattr(&stat->ctime);
-}
-
+u64 nfsd4_change_attribute(struct kstat *stat, struct inode *inode);
extern void fh_fill_pre_attrs(struct svc_fh *fhp);
extern void fh_fill_post_attrs(struct svc_fh *fhp);
extern void fh_fill_both_attrs(struct svc_fh *fhp);
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index dbdfef7ae85b..43fb57a301d3 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -170,9 +170,14 @@ static inline void fh_drop_write(struct svc_fh *fh)
static inline __be32 fh_getattr(const struct svc_fh *fh, struct kstat *stat)
{
+ u32 request_mask = STATX_BASIC_STATS;
struct path p = {.mnt = fh->fh_export->ex_path.mnt,
.dentry = fh->fh_dentry};
- return nfserrno(vfs_getattr(&p, stat, STATX_BASIC_STATS,
+
+ if (fh->fh_maxsize == NFS4_FHSIZE)
+ request_mask |= (STATX_BTIME | STATX_CHANGE_COOKIE);
+
+ return nfserrno(vfs_getattr(&p, stat, request_mask,
AT_STATX_SYNC_AS_STAT));
}
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;
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index fe848901fcc3..9f4d4bcbf251 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -213,7 +213,6 @@ struct export_operations {
bool write, u32 *device_generation);
int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
int nr_iomaps, struct iattr *iattr);
- u64 (*fetch_iversion)(struct inode *);
#define EXPORT_OP_NOWCC (0x1) /* don't collect v3 wcc data */
#define EXPORT_OP_NOSUBTREECHK (0x2) /* no subtree checking */
#define EXPORT_OP_CLOSE_BEFORE_UNLINK (0x4) /* close files before unlink */
diff --git a/include/linux/iversion.h b/include/linux/iversion.h
index e27bd4f55d84..f174ff1b59ee 100644
--- a/include/linux/iversion.h
+++ b/include/linux/iversion.h
@@ -9,8 +9,26 @@
* ---------------------------
* 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 or other relevant spec mandates that the
+ * ctime must change due to an operation, then the i_version counter must be
+ * incremented as well.
+ *
+ * Making the i_version update completely atomic with the operation itself would
+ * be prohibitively expensive. Traditionally the kernel has updated the times on
+ * directories after an operation that changes its contents. For regular files,
+ * the ctime is usually updated before the data is copied into the cache for a
+ * write. This means that there is a window of time when an observer can
+ * associate a new timestamp with old file contents. Since the purpose of the
+ * i_version is to allow for better cache coherency, the i_version must always
+ * be updated after the results of the operation are visible. Updating it before
+ * and after a change is also permitted. (Note that no filesystems currently do
+ * this. Fixing that is a work-in-progress).
*
* 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
@@ -234,42 +252,6 @@ inode_peek_iversion(const struct inode *inode)
return inode_peek_iversion_raw(inode) >> I_VERSION_QUERIED_SHIFT;
}
-/**
- * inode_query_iversion - read i_version for later use
- * @inode: inode from which i_version should be read
- *
- * Read the inode i_version counter. This should be used by callers that wish
- * to store the returned i_version for later comparison. This will guarantee
- * that a later query of the i_version will result in a different value if
- * anything has changed.
- *
- * In this implementation, we fetch the current value, set the QUERIED flag and
- * then try to swap it into place with a cmpxchg, if it wasn't already set. If
- * that fails, we try again with the newly fetched value from the cmpxchg.
- */
-static inline u64
-inode_query_iversion(struct inode *inode)
-{
- u64 cur, new;
-
- cur = inode_peek_iversion_raw(inode);
- do {
- /* If flag is already set, then no need to swap */
- if (cur & I_VERSION_QUERIED) {
- /*
- * This barrier (and the implicit barrier in the
- * cmpxchg below) pairs with the barrier in
- * inode_maybe_inc_iversion().
- */
- smp_mb();
- break;
- }
-
- new = cur | I_VERSION_QUERIED;
- } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
- return cur >> I_VERSION_QUERIED_SHIFT;
-}
-
/*
* For filesystems without any sort of change attribute, the best we can
* do is fake one up from the ctime:
@@ -283,6 +265,8 @@ static inline u64 time_to_chattr(struct timespec64 *t)
return chattr;
}
+u64 inode_query_iversion(struct inode *inode);
+
/**
* inode_eq_iversion_raw - check whether the raw i_version counter has changed
* @inode: inode to check
diff --git a/include/linux/stat.h b/include/linux/stat.h
index ff277ced50e9..52150570d37a 100644
--- a/include/linux/stat.h
+++ b/include/linux/stat.h
@@ -52,6 +52,15 @@ struct kstat {
u64 mnt_id;
u32 dio_mem_align;
u32 dio_offset_align;
+ 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
generated by cgit (git 2.34.1) at 2024-07-02 20:01:58 +0000