[Virtio-fs] [PATCH v2] fuse: invalidate inode attr in writeback cache mode
Eryu Guan
eguan at linux.alibaba.com
Tue May 12 02:29:04 UTC 2020
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 at linux.alibaba.com>
---
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
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