nfs: set invalid blocks after NFSv4 writes

Use the following command to test nfsv4(size of file1M is 1MB):
mount -t nfs -o vers=4.0,actimeo=60 127.0.0.1/dir1 /mnt
cp file1M /mnt
du -h /mnt/file1M  -->0 within 60s, then 1M

When write is done(cp file1M /mnt), will call this:
nfs_writeback_done
  nfs4_write_done
    nfs4_write_done_cb
      nfs_writeback_update_inode
        nfs_post_op_update_inode_force_wcc_locked(change, ctime, mtime
nfs_post_op_update_inode_force_wcc_locked
   nfs_set_cache_invalid
   nfs_refresh_inode_locked
     nfs_update_inode

nfsd write response contains change, ctime, mtime, the flag will be
clear after nfs_update_inode. Howerver, write response does not contain
space_used, previous open response contains space_used whose value is 0,
so inode->i_blocks is still 0.

nfs_getattr  -->called by "du -h"
  do_update |= force_sync || nfs_attribute_cache_expired -->false in 60s
  cache_validity = READ_ONCE(NFS_I(inode)->cache_validity)
  do_update |= cache_validity & (NFS_INO_INVALID_ATTR    -->false
  if (do_update) {
        __nfs_revalidate_inode
  }

Within 60s, does not send getattr request to nfsd, thus "du -h /mnt/file1M"
is 0.

Add a NFS_INO_INVALID_BLOCKS flag, set it when nfsv4 write is done.

Fixes: 16e14375 ("NFS: More fine grained attribute tracking")
Signed-off-by: NZheng Bin <zhengbin13@huawei.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/inode.c

@@ -833,6 +833,8 @@ int nfs_getattr(const struct path *path, struct kstat *stat,
 		do_update |= cache_validity & NFS_INO_INVALID_ATIME;
 	if (request_mask & (STATX_CTIME|STATX_MTIME))
 		do_update |= cache_validity & NFS_INO_REVAL_PAGECACHE;
+	if (request_mask & STATX_BLOCKS)
+		do_update |= cache_validity & NFS_INO_INVALID_BLOCKS;
 	if (do_update) {
 		/* Update the attribute cache */
 		if (!(server->flags & NFS_MOUNT_NOAC))
@@ -1764,7 +1766,8 @@ int nfs_post_op_update_inode_force_wcc_locked(struct inode *inode, struct nfs_fa
 	status = nfs_post_op_update_inode_locked(inode, fattr,
 			NFS_INO_INVALID_CHANGE
 			| NFS_INO_INVALID_CTIME
-			| NFS_INO_INVALID_MTIME);
+			| NFS_INO_INVALID_MTIME
+			| NFS_INO_INVALID_BLOCKS);
 	return status;
 }
 
@@ -1871,7 +1874,8 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 	nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR
 			| NFS_INO_INVALID_ATIME
 			| NFS_INO_REVAL_FORCED
-			| NFS_INO_REVAL_PAGECACHE);
+			| NFS_INO_REVAL_PAGECACHE
+			| NFS_INO_INVALID_BLOCKS);
 
 	/* Do atomic weak cache consistency updates */
 	nfs_wcc_update_inode(inode, fattr);
@@ -2033,8 +2037,12 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 		inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);
 	} else if (fattr->valid & NFS_ATTR_FATTR_BLOCKS_USED)
 		inode->i_blocks = fattr->du.nfs2.blocks;
-	else
+	else {
+		nfsi->cache_validity |= save_cache_validity &
+				(NFS_INO_INVALID_BLOCKS
+				| NFS_INO_REVAL_FORCED);
 		cache_revalidated = false;
+	}
 
 	/* Update attrtimeo value if we're out of the unstable period */
 	if (attr_changed) {

include/linux/nfs_fs.h

@@ -230,6 +230,7 @@ struct nfs4_copy_state {
 #define NFS_INO_INVALID_OTHER	BIT(12)		/* other attrs are invalid */
 #define NFS_INO_DATA_INVAL_DEFER	\
 				BIT(13)		/* Deferred cache invalidation */
+#define NFS_INO_INVALID_BLOCKS	BIT(14)         /* cached blocks are invalid */
 
 #define NFS_INO_INVALID_ATTR	(NFS_INO_INVALID_CHANGE \
 		| NFS_INO_INVALID_CTIME \