From: Vivek Goyal vgoyal@redhat.com
[ Upstream commit 3466958beb31a8e9d3a1441a34228ed088b84f3e ]
In fuse when a direct/write-through write happens we invalidate attrs because that might have updated mtime/ctime on server and cached mtime/ctime will be stale.
What about page writeback path. Looks like we don't invalidate attrs there. To be consistent, invalidate attrs in writeback path as well. Only exception is when writeback_cache is enabled. In that case we strust local mtime/ctime and there is no need to invalidate attrs.
Recently users started experiencing failure of xfstests generic/080, geneirc/215 and generic/614 on virtiofs. This happened only newer "stat" utility and not older one. This patch fixes the issue.
So what's the root cause of the issue. Here is detailed explanation.
generic/080 test does mmap write to a file, closes the file and then checks if mtime has been updated or not. When file is closed, it leads to flushing of dirty pages (and that should update mtime/ctime on server). But we did not explicitly invalidate attrs after writeback finished. Still generic/080 passed so far and reason being that we invalidated atime in fuse_readpages_end(). This is called in fuse_readahead() path and always seems to trigger before mmaped write.
So after mmaped write when lstat() is called, it sees that atleast one of the fields being asked for is invalid (atime) and that results in generating GETATTR to server and mtime/ctime also get updated and test passes.
But newer /usr/bin/stat seems to have moved to using statx() syscall now (instead of using lstat()). And statx() allows it to query only ctime or mtime (and not rest of the basic stat fields). That means when querying for mtime, fuse_update_get_attr() sees that mtime is not invalid (only atime is invalid). So it does not generate a new GETATTR and fill stat with cached mtime/ctime. And that means updated mtime is not seen by xfstest and tests start failing.
Invalidating attrs after writeback completion should solve this problem in a generic manner.
Signed-off-by: Vivek Goyal vgoyal@redhat.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/fuse/file.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c index eff4abaa87da..6e6d1e599869 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1776,8 +1776,17 @@ static void fuse_writepage_end(struct fuse_mount *fm, struct fuse_args *args, container_of(args, typeof(*wpa), ia.ap.args); struct inode *inode = wpa->inode; struct fuse_inode *fi = get_fuse_inode(inode); + struct fuse_conn *fc = get_fuse_conn(inode);
mapping_set_error(inode->i_mapping, error); + /* + * A writeback finished and this might have updated mtime/ctime on + * server making local mtime/ctime stale. Hence invalidate attrs. + * Do this only if writeback_cache is not enabled. If writeback_cache + * is enabled, we trust local ctime/mtime. + */ + if (!fc->writeback_cache) + fuse_invalidate_attr(inode); spin_lock(&fi->lock); rb_erase(&wpa->writepages_entry, &fi->writepages); while (wpa->next) {