Commit 73e3302f authored Apr 11, 2008 by Trond Myklebust

NFS: Fix nfs_wb_page() to always exit with an error or a clean page



It is possible for nfs_wb_page() to sometimes exit with 0 return value, yet
the page is left in a dirty state.
For instance in the case where the server rebooted, and the COMMIT request
failed, then all the previously "clean" pages which were cached by the
server, but were not guaranteed to have been writted out to disk,
have to be redirtied and resent to the server.
The fix is to have nfs_wb_page_priority() check that the page is clean
before it exits...

This fixes a condition that triggers the BUG_ON(PagePrivate(page)) in
nfs_create_request() when we're in the nfs_readpage() path.

Also eliminate a redundant BUG_ON(!PageLocked(page)) while we're at it. It
turns out that clear_page_dirty_for_io() has the exact same test.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

parent 080a1f14

fs/nfs/write.c

+12 −11

Original line number	Diff line number	Diff line
		@@ -1493,18 +1493,19 @@ static int nfs_wb_page_priority(struct inode inode, struct page page,
		};
		int ret;

		BUG_ON(!PageLocked(page));
		do {
		if (clear_page_dirty_for_io(page)) {
		ret = nfs_writepage_locked(page, &wbc);
		if (ret < 0)
		goto out;
		}
		if (!PagePrivate(page))
		return 0;
		goto out_error;
		} else if (!PagePrivate(page))
		break;
		ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
		if (ret >= 0)
		if (ret < 0)
		goto out_error;
		} while (PagePrivate(page));
		return 0;
		out:
		out_error:
		__mark_inode_dirty(inode, I_DIRTY_PAGES);
		return ret;
		}

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