fuse: truncate pagecache range on hole punch
fuse supports hole punch via the fallocate() FALLOC_FL_PUNCH_HOLE
interface. When a hole punch is passed through, the page cache
is not cleared and thus allows reading stale data from the cache.
This is easily demonstrable (using FOPEN_KEEP_CACHE) by reading a
smallish random data file into cache, punching a hole and creating
a copy of the file. Drop caches or remount and observe that the
original file no longer matches the file copied after the hole
punch. The original file contains a zeroed range and the latter
file contains stale data.
Protect against writepage requests in progress and punch out the
associated page cache range after a successful client fs hole
punch.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index fe19132..a200a2d 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -16,6 +16,7 @@
#include <linux/compat.h>
#include <linux/swap.h>
#include <linux/aio.h>
+#include <linux/falloc.h>
static const struct file_operations fuse_direct_io_file_operations;
@@ -2453,6 +2454,7 @@
loff_t length)
{
struct fuse_file *ff = file->private_data;
+ struct inode *inode = file->f_inode;
struct fuse_conn *fc = ff->fc;
struct fuse_req *req;
struct fuse_fallocate_in inarg = {
@@ -2466,9 +2468,16 @@
if (fc->no_fallocate)
return -EOPNOTSUPP;
+ if (mode & FALLOC_FL_PUNCH_HOLE) {
+ mutex_lock(&inode->i_mutex);
+ fuse_set_nowrite(inode);
+ }
+
req = fuse_get_req_nopages(fc);
- if (IS_ERR(req))
- return PTR_ERR(req);
+ if (IS_ERR(req)) {
+ err = PTR_ERR(req);
+ goto out;
+ }
req->in.h.opcode = FUSE_FALLOCATE;
req->in.h.nodeid = ff->nodeid;
@@ -2483,6 +2492,15 @@
}
fuse_put_request(fc, req);
+out:
+ if (mode & FALLOC_FL_PUNCH_HOLE) {
+ if (!err)
+ truncate_pagecache_range(inode, offset,
+ offset + length - 1);
+ fuse_release_nowrite(inode);
+ mutex_unlock(&inode->i_mutex);
+ }
+
return err;
}