[Devel] [PATCH VZ9 1/10] fs/fuse: invalidate file attrs when it is necessary

[Alexey Kuznetsov]

The patch is executed only for vstorage (close wait condition), to be safe
No doubts the same problem exists for mainstream, but we do not care
and leave it alone. Note: we do not mean such attributes as st_size
and st_mtime - they are handled entirely in kernel side for write
cached files, it is rather about st_blocks.

When doing direct writes attributes are invalidated on each write,
but this invalidation is missing for cached writes, so that user
does not see increase in st_blocks after write.

We add it to two places: after fsync - this is definitely
necessary for vstorage raid files even in O_DIRECT mode
because fsync changes space allocation. And after completion
of write_page. Mainstream added such invalidation but skipped
it for write_cache files by some obscure reasons explained
in long commit comment, which is just a bullshit: indeed
if we mean update mtime/size, it is noop for write_cache files,
but st_blocks still needs invalidation. So, just leave
non-vstorage alone.

Signed-off-by: Alexey Kuznetsov <kuznet at virtuozzo.com>
---
 fs/fuse/file.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 6a89f96..2112dcf 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -776,6 +776,9 @@ static int fuse_fsync(struct file *file, loff_t start, loff_t end,
 		fc->no_fsync = 1;
 		err = 0;
 	}
+	/* vstorage changes i_blocks on fsync, so we have to invalidate. */
+	if (fc->close_wait)
+		fuse_invalidate_attr(inode);
 	return err;
 out:
 	inode_unlock(inode);
@@ -2139,7 +2142,7 @@ static void fuse_writepage_end(struct fuse_mount *fm, struct fuse_args *args,
 	 * Do this only if writeback_cache is not enabled.  If writeback_cache
 	 * is enabled, we trust local ctime/mtime.
 	 */
-	if (!fc->writeback_cache)
+	if (!fc->writeback_cache || fc->close_wait)
 		fuse_invalidate_attr(inode);
 	spin_lock(&fi->lock);
 	rb_erase(&wpa->writepages_entry, &fi->writepages);
-- 
1.8.3.1