From: Maxim Patlasov Date: Thu, 13 Jun 2013 08:16:39 +0000 (+0400) Subject: fuse: hold i_mutex in fuse_file_fallocate() X-Git-Tag: v3.10~24^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=14c14414d157ea851119c96c61a17306a2b4a035;p=pandora-kernel.git fuse: hold i_mutex in fuse_file_fallocate() Changing size of a file on server and local update (fuse_write_update_size) should be always protected by inode->i_mutex. Otherwise a race like this is possible: 1. Process 'A' calls fallocate(2) to extend file (~FALLOC_FL_KEEP_SIZE). fuse_file_fallocate() sends FUSE_FALLOCATE request to the server. 2. Process 'B' calls ftruncate(2) shrinking the file. fuse_do_setattr() sends shrinking FUSE_SETATTR request to the server and updates local i_size by i_size_write(inode, outarg.attr.size). 3. Process 'A' resumes execution of fuse_file_fallocate() and calls fuse_write_update_size(inode, offset + length). But 'offset + length' was obsoleted by ftruncate from previous step. Changed in v2 (thanks Brian and Anand for suggestions): - made relation between mutex_lock() and fuse_set_nowrite(inode) more explicit and clear. - updated patch description to use ftruncate(2) in example Signed-off-by: Maxim V. Patlasov Reviewed-by: Brian Foster Signed-off-by: Miklos Szeredi --- Reading git-diff-tree failed