Cifs has a following race between hole punching and page fault:
CPU1 CPU2
smb3_fallocate()
smb3_punch_hole()
truncate_pagecache_range()
filemap_fault()
- loads old data into the
page cache
SMB2_ioctl(..., FSCTL_SET_ZERO_DATA, ...)
And now we have stale data in the page cache. Fix the problem by locking
out faults (as well as reads) using mapping->invalidate_lock while hole
punch is running.
CC: Steve French <sfrench@samba.org>
CC: linux-cifs@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
return rc;
}
+ filemap_invalidate_lock(inode->i_mapping);
/*
* We implement the punch hole through ioctl, so we need remove the page
* caches first, otherwise the data may be inconsistent with the server.
sizeof(struct file_zero_data_information),
CIFSMaxBufSize, NULL, NULL);
free_xid(xid);
+ filemap_invalidate_unlock(inode->i_mapping);
return rc;
}