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.

Reviewed-by: Tony Nguyen <[email protected]>
Reviewed-by: Allan Jude <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Reviewed-by: Ryan Moeller <[email protected]>
Signed-off-by: Richard Yao <[email protected]>
Closes #8507

1 files changed, 8 insertions, 4 deletions

diff --git a/module/os/linux/zfs/zfs_znode.c b/module/os/linux/zfs/zfs_znode.c
index 8cc454468..6859832ab 100644
--- a/module/os/linux/zfs/zfs_znode.c
+++ b/module/os/linux/zfs/zfs_znode.c
@@ -525,9 +525,9 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 	uint64_t tmp_gen;
 	uint64_t links;
 	uint64_t z_uid, z_gid;
-	uint64_t atime[2], mtime[2], ctime[2];
+	uint64_t atime[2], mtime[2], ctime[2], btime[2];
 	uint64_t projid = ZFS_DEFAULT_PROJID;
-	sa_bulk_attr_t bulk[11];
+	sa_bulk_attr_t bulk[12];
 	int count = 0;
 
 	ASSERT(zfsvfs != NULL);
@@ -569,6 +569,7 @@ 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);
+	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CRTIME(zfsvfs), NULL, &btime, 16);
 
 	if (sa_bulk_lookup(zp->z_sa_hdl, bulk, count) != 0 || tmp_gen == 0 ||
 	    (dmu_objset_projectquota_enabled(zfsvfs->z_os) &&
@@ -596,6 +597,7 @@ 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);
+	ZFS_TIME_DECODE(&zp->z_btime, btime);
 
 	ip->i_ino = zp->z_id;
 	zfs_znode_update_vfs(zp);
@@ -1169,12 +1171,12 @@ zfs_rezget(znode_t *zp)
 	uint64_t obj_num = zp->z_id;
 	uint64_t mode;
 	uint64_t links;
-	sa_bulk_attr_t bulk[10];
+	sa_bulk_attr_t bulk[11];
 	int err;
 	int count = 0;
 	uint64_t gen;
 	uint64_t z_uid, z_gid;
-	uint64_t atime[2], mtime[2], ctime[2];
+	uint64_t atime[2], mtime[2], ctime[2], btime[2];
 	uint64_t projid = ZFS_DEFAULT_PROJID;
 	znode_hold_t *zh;
 
@@ -1244,6 +1246,7 @@ zfs_rezget(znode_t *zp)
 	    &mtime, 16);
 	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
 	    &ctime, 16);
+	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CRTIME(zfsvfs), NULL, &btime, 16);
 
 	if (sa_bulk_lookup(zp->z_sa_hdl, bulk, count)) {
 		zfs_znode_dmu_fini(zp);
@@ -1269,6 +1272,7 @@ 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);
+	ZFS_TIME_DECODE(&zp->z_btime, btime);
 
 	if ((uint32_t)gen != ZTOI(zp)->i_generation) {
 		zfs_znode_dmu_fini(zp);