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authorTejun Heo <tj@kernel.org>2014-02-03 14:03:00 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-07 15:42:41 -0800
commit81c173cb5e87fbb47ccd80630faefe39bbf68449 (patch)
tree7b5aaa2255ac62f2879e2431062f9b96a38e8574 /fs/kernfs/kernfs-internal.h
parent182fd64b66342219d6fcf2b84d337529d120d95c (diff)
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kernfs: remove KERNFS_REMOVED
KERNFS_REMOVED is used to mark half-initialized and dying nodes so that they don't show up in lookups and deny adding new nodes under or renaming it; however, its role overlaps that of deactivation. It's necessary to deny addition of new children while removal is in progress; however, this role considerably intersects with deactivation - KERNFS_REMOVED prevents new children while deactivation prevents new file operations. There's no reason to have them separate making things more complex than necessary. This patch removes KERNFS_REMOVED. * Instead of KERNFS_REMOVED, each node now starts its life deactivated. This means that we now use both atomic_add() and atomic_sub() on KN_DEACTIVATED_BIAS, which is INT_MIN. The compiler generates an overflow warnings when negating INT_MIN as the negation can't be represented as a positive number. Nothing is actually broken but let's bump BIAS by one to avoid the warnings for archs which negates the subtrahend.. * A new helper kernfs_active() which tests whether kn->active >= 0 is added for convenience and lockdep annotation. All KERNFS_REMOVED tests are replaced with negated kernfs_active() tests. * __kernfs_remove() is updated to deactivate, but not drain, all nodes in the subtree instead of setting KERNFS_REMOVED. This removes deactivation from kernfs_deactivate(), which is now renamed to kernfs_drain(). * Sanity check on KERNFS_REMOVED in kernfs_put() is replaced with checks on the active ref. * Some comment style updates in the affected area. v2: Reordered before removal path restructuring. kernfs_active() dropped and kernfs_get/put_active() used instead. RB_EMPTY_NODE() used in the lookup paths. v3: Reverted most of v2 except for creating a new node with KN_DEACTIVATED_BIAS. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs/kernfs-internal.h')
-rw-r--r--fs/kernfs/kernfs-internal.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 46b58de794d6..a91d7a1113d9 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -26,7 +26,8 @@ struct kernfs_iattrs {
struct simple_xattrs xattrs;
};
-#define KN_DEACTIVATED_BIAS INT_MIN
+/* +1 to avoid triggering overflow warning when negating it */
+#define KN_DEACTIVATED_BIAS (INT_MIN + 1)
/* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */