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kernfs: invoke kernfs_unmap_bin_file() directly from kernfs_deactivate()

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kernfs_unmap_bin_file() is supposed to unmap all memory mappings of
the target file before kernfs_remove() finishes; however, it currently
is being called from kernfs_addrm_finish() and has the same race
problem as the original implementation of deactivation when there are
multiple removers - only the remover which snatches the node to its
addrm_cxt->removed list is guaranteed to wait for its completion
before returning.

It can be easily fixed by moving kernfs_unmap_bin_file() invocation
from kernfs_addrm_finish() to kernfs_deactivated().  The function may
be called multiple times but that shouldn't do any harm.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo 2014-02-03 14:02:57 -05:00 committed by Greg Kroah-Hartman
parent 35beab0635
commit ccf02aaf81
1 changed files with 6 additions and 4 deletions
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10
fs/kernfs/dir.c
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@ -177,9 +177,10 @@ void kernfs_put_active(struct kernfs_node *kn)
* kernfs_deactivate - deactivate kernfs_node
* @kn: kernfs_node to deactivate
*
* Deny new active references and drain existing ones. Mutiple
* removers may invoke this function concurrently on @kn and all will
* return after deactivation and draining are complete.
* Deny new active references, drain existing ones and nuke all
* existing mmaps. Mutiple removers may invoke this function
* concurrently on @kn and all will return after deactivation and
* draining are complete.
*/
static void kernfs_deactivate(struct kernfs_node *kn)
__releases(&kernfs_mutex) __acquires(&kernfs_mutex)
@ -213,6 +214,8 @@ static void kernfs_deactivate(struct kernfs_node *kn)
rwsem_release(&kn->dep_map, 1, _RET_IP_);
}
kernfs_unmap_bin_file(kn);
mutex_lock(&kernfs_mutex);
}
@ -493,7 +496,6 @@ void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt)
acxt->removed = kn->u.removed_list;
kernfs_unmap_bin_file(kn);
kernfs_put(kn);
}
}