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Commit 85784f93 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: only dirty ITER_IOVEC pages for direct read 



If a page is already locked, attempting to dirty it leads to a deadlock
in lock_page().  This is what currently happens to ITER_BVEC pages when
a dio-enabled loop device is backed by ceph:

  $ losetup --direct-io /dev/loop0 /mnt/cephfs/img
  $ xfs_io -c 'pread 0 4k' /dev/loop0

Follow other file systems and only dirty ITER_IOVEC pages.

Cc: stable@kernel.org
Signed-off-by: default avatar"Yan, Zheng" <zyan@redhat.com>
Reviewed-by: default avatarIlya Dryomov <idryomov@gmail.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 3eb2ce82

fs/ceph/file.c

+6 −3
Original line number Diff line number Diff line
@@ -640,7 +640,8 @@ static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *to, 
struct ceph_aio_request {

	struct kiocb *iocb;

	size_t total_len;

	int write;

	bool write;

	bool should_dirty;

	int error;

	struct list_head osd_reqs;

	unsigned num_reqs;
@@ -750,7 +751,7 @@ static void ceph_aio_complete_req(struct ceph_osd_request *req) 
		}

	}



	ceph_put_page_vector(osd_data->pages, num_pages, !aio_req->write);

	ceph_put_page_vector(osd_data->pages, num_pages, aio_req->should_dirty);

	ceph_osdc_put_request(req);



	if (rc < 0)
@@ -847,6 +848,7 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter, 
	size_t count = iov_iter_count(iter);

	loff_t pos = iocb->ki_pos;

	bool write = iov_iter_rw(iter) == WRITE;

	bool should_dirty = !write && iter_is_iovec(iter);



	if (write && ceph_snap(file_inode(file)) != CEPH_NOSNAP)

		return -EROFS;
@@ -914,6 +916,7 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter, 
			if (aio_req) {

				aio_req->iocb = iocb;

				aio_req->write = write;

				aio_req->should_dirty = should_dirty;

				INIT_LIST_HEAD(&aio_req->osd_reqs);

				if (write) {

					aio_req->mtime = mtime;
@@ -971,7 +974,7 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter, 
				len = ret;

		}



		ceph_put_page_vector(pages, num_pages, !write);

		ceph_put_page_vector(pages, num_pages, should_dirty);



		ceph_osdc_put_request(req);

		if (ret < 0)