Linux 4.11 compat: statx support

Linux 4.11 added a new statx system call that allows us to expose crtime
as btime. We do this by caching crtime in the znode to match how atime,
ctime and mtime are cached in the inode.

statx also introduced a new way of reporting whether the immutable,
append and nodump bits have been set. It adds support for reporting
compression and encryption, but the semantics on other filesystems is
not just to report compression/encryption, but to allow it to be turned
on/off at the file level. We do not support that.

We could implement semantics where we refuse to allow user modification
of the bit, but we would need to do a dnode_hold() in zfs_znode_alloc()
to find out encryption/compression information. That would introduce
locking that will have a minor (although unmeasured) performance cost.
It also would be inferior to zdb, which reports far more detailed
information. We therefore omit reporting of encryption/compression
through statx in favor of recommending that users interested in such
information use zdb.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Closes openzfs#8507

include/os/linux/zfs/sys/zfs_znode_impl.h

@@ -36,20 +36,25 @@
 #include <sys/list.h>
 #include <sys/dmu.h>
 #include <sys/sa.h>
+#include <sys/time.h>
 #include <sys/zfs_vfsops.h>
 #include <sys/rrwlock.h>
 #include <sys/zfs_sa.h>
 #include <sys/zfs_stat.h>
 #include <sys/zfs_rlock.h>
 
-
 #ifdef	__cplusplus
 extern "C" {
 #endif
 
+#ifdef STATX_BTIME
 #define	ZNODE_OS_FIELDS			\
+	inode_timespec_t z_btime; /* creation/birth time (cached) */ \
 	struct inode	z_inode;
-
+#else
+#define	ZNODE_OS_FIELDS			\
+	struct inode	z_inode;
+#endif
 
 /*
  * Convert between znode pointers and inode pointers

module/os/linux/zfs/zfs_znode.c

@@ -527,7 +527,12 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 	uint64_t z_uid, z_gid;
 	uint64_t atime[2], mtime[2], ctime[2];
 	uint64_t projid = ZFS_DEFAULT_PROJID;
+#ifdef STATX_BTIME
+	uint64_t btime[2];
+	sa_bulk_attr_t bulk[12];
+#else
 	sa_bulk_attr_t bulk[11];
+#endif
 	int count = 0;
 
 	ASSERT(zfsvfs != NULL);
@@ -569,6 +574,9 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_ATIME(zfsvfs), NULL, &atime, 16);
 	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL, &mtime, 16);
 	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL, &ctime, 16);
+#ifdef STATX_BTIME
+	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CRTIME(zfsvfs), NULL, &btime, 16);
+#endif
 
 	if (sa_bulk_lookup(zp->z_sa_hdl, bulk, count) != 0 || tmp_gen == 0 ||
 	    (dmu_objset_projectquota_enabled(zfsvfs->z_os) &&
@@ -596,6 +604,9 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 	ZFS_TIME_DECODE(&ip->i_atime, atime);
 	ZFS_TIME_DECODE(&ip->i_mtime, mtime);
 	ZFS_TIME_DECODE(&ip->i_ctime, ctime);
+#ifdef STATX_BTIME
+	ZFS_TIME_DECODE(&zp->z_btime, btime);
+#endif
 
 	ip->i_ino = zp->z_id;
 	zfs_znode_update_vfs(zp);
@@ -1169,13 +1180,18 @@ zfs_rezget(znode_t *zp)
 	uint64_t obj_num = zp->z_id;
 	uint64_t mode;
 	uint64_t links;
-	sa_bulk_attr_t bulk[10];
 	int err;
 	int count = 0;
 	uint64_t gen;
 	uint64_t z_uid, z_gid;
 	uint64_t atime[2], mtime[2], ctime[2];
 	uint64_t projid = ZFS_DEFAULT_PROJID;
+#ifdef STATX_BTIME
+	uint64_t btime[2];
+	sa_bulk_attr_t bulk[11];
+#else
+	sa_bulk_attr_t bulk[10];
+#endif
 	znode_hold_t *zh;
 
 	/*
@@ -1244,6 +1260,9 @@ zfs_rezget(znode_t *zp)
 	    &mtime, 16);
 	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
 	    &ctime, 16);
+#ifdef STATX_BTIME
+	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CRTIME(zfsvfs), NULL, &btime, 16);
+#endif
 
 	if (sa_bulk_lookup(zp->z_sa_hdl, bulk, count)) {
 		zfs_znode_dmu_fini(zp);
@@ -1269,6 +1288,9 @@ zfs_rezget(znode_t *zp)
 	ZFS_TIME_DECODE(&ZTOI(zp)->i_atime, atime);
 	ZFS_TIME_DECODE(&ZTOI(zp)->i_mtime, mtime);
 	ZFS_TIME_DECODE(&ZTOI(zp)->i_ctime, ctime);
+#ifdef STATX_BTIME
+	ZFS_TIME_DECODE(&zp->z_btime, btime);
+#endif
 
 	if ((uint32_t)gen != ZTOI(zp)->i_generation) {
 		zfs_znode_dmu_fini(zp);

module/os/linux/zfs/zpl_inode.c

@@ -378,6 +378,7 @@ zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
 {
 	int error;
 	fstrans_cookie_t cookie;
+	struct inode *ip = path->dentry->d_inode;
 
 	cookie = spl_fstrans_mark();
 
@@ -386,10 +387,34 @@ zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
 	 */
 
 #ifdef HAVE_USERNS_IOPS_GETATTR
-	error = -zfs_getattr_fast(user_ns, path->dentry->d_inode, stat);
+	error = -zfs_getattr_fast(user_ns, ip, stat);
 #else
-	error = -zfs_getattr_fast(kcred->user_ns, path->dentry->d_inode, stat);
+	error = -zfs_getattr_fast(kcred->user_ns, ip, stat);
 #endif
+
+#ifdef STATX_BTIME
+	stat->btime = ITOZ(ip)->z_btime;
+	stat->result_mask |= STATX_BTIME;
+#endif
+
+#ifdef STATX_ATTR_IMMUTABLE
+	if (zfs_flags & ZFS_IMMUTABLE)
+		stat->attributes |= STATX_ATTR_IMMUTABLE;
+	stat->attributes_mask |= STATX_ATTR_IMMUTABLE;
+#endif
+
+#ifdef STATX_ATTR_APPEND
+	if (zfs_flags & ZFS_APPENDONLY)
+		stat->attributes |= STATX_ATTR_APPEND;
+	stat->attributes_mask |= STATX_ATTR_APPEND;
+#endif
+
+#ifdef STATX_ATTR_NODUMP
+	if (zfs_flags & ZFS_NODUMP)
+		stat->attributes |= STATX_ATTR_NODUMP;
+	stat->attributes_mask |= STATX_ATTR_NODUMP;
+#endif
+
 	spl_fstrans_unmark(cookie);
 	ASSERT3S(error, <=, 0);