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author | Pavel Emelyanov <xemul@openvz.org> | 2013-10-10 17:12:05 +0400 |
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committer | Miklos Szeredi <mszeredi@suse.cz> | 2014-04-02 15:38:50 +0200 |
commit | ea8cd33390fafc1eca06a26e6a9c7bf1d386526f (patch) | |
tree | eb0b3ecdf4760b3b96bc2d0d179e4c59c33d7ade /fs/fuse/cuse.c | |
parent | fe38d7df230b022e72014ef7aa799a4f2acfecf3 (diff) | |
download | linux-stable-ea8cd33390fafc1eca06a26e6a9c7bf1d386526f.tar.gz linux-stable-ea8cd33390fafc1eca06a26e6a9c7bf1d386526f.tar.bz2 linux-stable-ea8cd33390fafc1eca06a26e6a9c7bf1d386526f.zip |
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 <MPatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Diffstat (limited to 'fs/fuse/cuse.c')
-rw-r--r-- | fs/fuse/cuse.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index b96a49b37d66..23e363f38302 100644 --- a/fs/fuse/cuse.c +++ b/fs/fuse/cuse.c @@ -95,7 +95,7 @@ static ssize_t cuse_read(struct file *file, char __user *buf, size_t count, struct iovec iov = { .iov_base = buf, .iov_len = count }; struct fuse_io_priv io = { .async = 0, .file = file }; - return fuse_direct_io(&io, &iov, 1, count, &pos, 0); + return fuse_direct_io(&io, &iov, 1, count, &pos, FUSE_DIO_CUSE); } static ssize_t cuse_write(struct file *file, const char __user *buf, @@ -109,7 +109,8 @@ static ssize_t cuse_write(struct file *file, const char __user *buf, * No locking or generic_write_checks(), the server is * responsible for locking and sanity checks. */ - return fuse_direct_io(&io, &iov, 1, count, &pos, 1); + return fuse_direct_io(&io, &iov, 1, count, &pos, + FUSE_DIO_WRITE | FUSE_DIO_CUSE); } static int cuse_open(struct inode *inode, struct file *file) |