From 8fba54aebbdf1f999738121922e74bf796ad60ee Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 24 Aug 2016 18:17:04 +0200 Subject: [PATCH] fuse: direct-io: don't dirty ITER_BVEC pages When reading from a loop device backed by a fuse file it deadlocks on lock_page(). This is because the page is already locked by the read() operation done on the loop device. In this case we don't want to either lock the page or dirty it. So do what fs/direct-io.c does: only dirty the page for ITER_IOVEC vectors. Reported-by: Sheng Yang Fixes: aa4d86163e4e ("block: loop: switch to VFS ITER_BVEC") Signed-off-by: Miklos Szeredi Cc: # v4.1+ Reviewed-by: Sheng Yang Reviewed-by: Ashish Samant Tested-by: Sheng Yang Tested-by: Ashish Samant --- fs/fuse/file.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index f394aff59c36..3988b43c2f5a 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -530,13 +530,13 @@ void fuse_read_fill(struct fuse_req *req, struct file *file, loff_t pos, req->out.args[0].size = count; } -static void fuse_release_user_pages(struct fuse_req *req, int write) +static void fuse_release_user_pages(struct fuse_req *req, bool should_dirty) { unsigned i; for (i = 0; i < req->num_pages; i++) { struct page *page = req->pages[i]; - if (write) + if (should_dirty) set_page_dirty_lock(page); put_page(page); } @@ -1320,6 +1320,7 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter, loff_t *ppos, int flags) { int write = flags & FUSE_DIO_WRITE; + bool should_dirty = !write && iter_is_iovec(iter); int cuse = flags & FUSE_DIO_CUSE; struct file *file = io->file; struct inode *inode = file->f_mapping->host; @@ -1363,7 +1364,7 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter, nres = fuse_send_read(req, io, pos, nbytes, owner); if (!io->async) - fuse_release_user_pages(req, !write); + fuse_release_user_pages(req, should_dirty); if (req->out.h.error) { err = req->out.h.error; break;