fuse: Trust kernel i_size only
Make fuse think that when writeback is on the inode's i_size is always
up-to-date and not update it with the value received from the userspace.
This is done because the page cache code may update i_size without letting
the FS know.
This assumption implies fixing the previously introduced short-read helper --
when a short read occurs the 'hole' is filled with zeroes.
fuse_file_fallocate() is also fixed because now we should keep i_size up to
date, so it must be updated if FUSE_FALLOCATE request succeeded.
Signed-off-by: Maxim V. Patlasov <MPatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 592d7b4..c091a17 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -675,9 +675,26 @@
u64 attr_ver)
{
size_t num_read = req->out.args[0].size;
+ struct fuse_conn *fc = get_fuse_conn(inode);
- loff_t pos = page_offset(req->pages[0]) + num_read;
- fuse_read_update_size(inode, pos, attr_ver);
+ if (fc->writeback_cache) {
+ /*
+ * A hole in a file. Some data after the hole are in page cache,
+ * but have not reached the client fs yet. So, the hole is not
+ * present there.
+ */
+ int i;
+ int start_idx = num_read >> PAGE_CACHE_SHIFT;
+ size_t off = num_read & (PAGE_CACHE_SIZE - 1);
+
+ for (i = start_idx; i < req->num_pages; i++) {
+ zero_user_segment(req->pages[i], off, PAGE_CACHE_SIZE);
+ off = 0;
+ }
+ } else {
+ loff_t pos = page_offset(req->pages[0]) + num_read;
+ fuse_read_update_size(inode, pos, attr_ver);
+ }
}
static int fuse_readpage(struct file *file, struct page *page)