From ea8cd33390fafc1eca06a26e6a9c7bf1d386526f Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Thu, 10 Oct 2013 17:12:05 +0400 Subject: fuse: Fix O_DIRECT operations vs cached writeback misorder The problem is: 1. write cached data to a file 2. read directly from the same file (via another fd) The 2nd operation may read stale data, i.e. the one that was in a file before the 1st op. Problem is in how fuse manages writeback. When direct op occurs the core kernel code calls filemap_write_and_wait to flush all the cached ops in flight. But fuse acks the writeback right after the ->writepages callback exits w/o waiting for the real write to happen. Thus the subsequent direct op proceeds while the real writeback is still in flight. This is a problem for backends that reorder operation. Fix this by making the fuse direct IO callback explicitly wait on the in-flight writeback to finish. Signed-off-by: Maxim Patlasov Signed-off-by: Miklos Szeredi --- fs/fuse/fuse_i.h | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'fs/fuse/fuse_i.h') diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 1e6ad6d43051..a257ed8ebee6 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -868,9 +868,20 @@ int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid, int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file, bool isdir); + +/** + * fuse_direct_io() flags + */ + +/** If set, it is WRITE; otherwise - READ */ +#define FUSE_DIO_WRITE (1 << 0) + +/** CUSE pass fuse_direct_io() a file which f_mapping->host is not from FUSE */ +#define FUSE_DIO_CUSE (1 << 1) + ssize_t fuse_direct_io(struct fuse_io_priv *io, const struct iovec *iov, unsigned long nr_segs, size_t count, loff_t *ppos, - int write); + int flags); long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg, unsigned int flags); long fuse_ioctl_common(struct file *file, unsigned int cmd, -- cgit v1.2.3