Under writeback mode, inode->i_blocks is not updated, making utils du read st.blocks as 0. For example, when using virtiofs (cache=always & nondax mode) with writeback_cache enabled, writing a new file and check its disk usage with du, du reports 0 usage. # uname -r 5.6.0-rc6+ # mount -t virtiofs virtiofs /mnt/virtiofs # rm -f /mnt/virtiofs/testfile # create new file and do extend write # xfs_io -fc "pwrite 0 4k" /mnt/virtiofs/testfile wrote 4096/4096 bytes at offset 0 4 KiB, 1 ops; 0.0001 sec (28.103 MiB/sec and 7194.2446 ops/sec) # du -k /mnt/virtiofs/testfile 0 <==== disk usage is 0 # stat -c %s,%b /mnt/virtiofs/testfile 4096,0 <==== i_size is correct, but st_blocks is 0 Fix it by invalidating attr in fuse_flush(), so we get up-to-date attr from server on next getattr. Signed-off-by: Eryu Guan <eguan@xxxxxxxxxxxxxxxxx> --- v2: - do fuse_invalidate_attr() in fuse_flush() as Miklos suggested fs/fuse/file.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 9d67b830fb7a..4bb399caec01 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -445,8 +445,9 @@ static int fuse_flush(struct file *file, fl_owner_t id) if (is_bad_inode(inode)) return -EIO; + err = 0; if (fc->no_flush) - return 0; + goto inval_attr_out; err = write_inode_now(inode, 1); if (err) @@ -475,6 +476,14 @@ static int fuse_flush(struct file *file, fl_owner_t id) fc->no_flush = 1; err = 0; } + +inval_attr_out: + /* + * In memory i_blocks is not maintained by fuse, if writeback cache is + * enabled, i_blocks from cached attr may not be accurate. + */ + if (!err && fc->writeback_cache) + fuse_invalidate_attr(inode); return err; } -- 2.26.1.107.gefe3874
