From 3634a6327815d39dd93e5c44a602daae91c66297 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Fri, 17 May 2013 09:30:32 -0400 Subject: [PATCH] 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 Signed-off-by: Miklos Szeredi --- fs/fuse/file.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) 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 #include #include +#include static const struct file_operations fuse_direct_io_file_operations; @@ -2453,6 +2454,7 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, 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 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, 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 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, } 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; } -- 2.7.4