From: Eric W. Biederman Date: Thu, 3 Oct 2013 08:31:18 +0000 (-0700) Subject: vfs: Add a function to lazily unmount all mounts from any dentry. X-Git-Tag: fixes-against-v3.18-rc2~105^2~50 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=80b5dce8c59b0de1ed6e403b8298e02dcb4db64b;p=pandora-kernel.git vfs: Add a function to lazily unmount all mounts from any dentry. The new function detach_mounts comes in two pieces. The first piece is a static inline test of d_mounpoint that returns immediately without taking any locks if d_mounpoint is not set. In the common case when mountpoints are absent this allows the vfs to continue running with it's same cacheline foot print. The second piece of detach_mounts __detach_mounts actually does the work and it assumes that a mountpoint is present so it is slow and takes namespace_sem for write, and then locks the mount hash (aka mount_lock) after a struct mountpoint has been found. With those two locks held each entry on the list of mounts on a mountpoint is selected and lazily unmounted until all of the mount have been lazily unmounted. v7: Wrote a proper change description and removed the changelog documenting deleted wrong turns. Signed-off-by: Eric W. Biederman Signed-off-by: Al Viro --- Reading git-diff-tree failed