dentry_kill(): don't try to remove from shrink list
If the victim in on the shrink list, don't remove it from there.
If shrink_dentry_list() manages to remove it from the list before
we are done - fine, we'll just free it as usual. If not - mark
it with new flag (DCACHE_MAY_FREE) and leave it there.
Eventually, shrink_dentry_list() will get to it, remove the sucker
from shrink list and call dentry_kill(dentry, 0). Which is where
we'll deal with freeing.
Since now dentry_kill(dentry, 0) may happen after or during
dentry_kill(dentry, 1), we need to recognize that (by seeing
DCACHE_DENTRY_KILLED already set), unlock everything
and either free the sucker (in case DCACHE_MAY_FREE has been
set) or leave it for ongoing dentry_kill(dentry, 1) to deal with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/dcache.c b/fs/dcache.c
index e482775..58e26be 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -468,7 +468,14 @@
__releases(dentry->d_lock)
{
struct inode *inode;
- struct dentry *parent;
+ struct dentry *parent = NULL;
+ bool can_free = true;
+
+ if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
+ can_free = dentry->d_flags & DCACHE_MAY_FREE;
+ spin_unlock(&dentry->d_lock);
+ goto out;
+ }
inode = dentry->d_inode;
if (inode && !spin_trylock(&inode->i_lock)) {
@@ -479,9 +486,7 @@
}
return dentry; /* try again with same dentry */
}
- if (IS_ROOT(dentry))
- parent = NULL;
- else
+ if (!IS_ROOT(dentry))
parent = dentry->d_parent;
if (parent && !spin_trylock(&parent->d_lock)) {
if (inode)
@@ -504,8 +509,6 @@
if (dentry->d_flags & DCACHE_LRU_LIST) {
if (!(dentry->d_flags & DCACHE_SHRINK_LIST))
d_lru_del(dentry);
- else
- d_shrink_del(dentry);
}
/* if it was on the hash then remove it */
__d_drop(dentry);
@@ -527,7 +530,15 @@
if (dentry->d_op && dentry->d_op->d_release)
dentry->d_op->d_release(dentry);
- dentry_free(dentry);
+ spin_lock(&dentry->d_lock);
+ if (dentry->d_flags & DCACHE_SHRINK_LIST) {
+ dentry->d_flags |= DCACHE_MAY_FREE;
+ can_free = false;
+ }
+ spin_unlock(&dentry->d_lock);
+out:
+ if (likely(can_free))
+ dentry_free(dentry);
return parent;
}
@@ -829,7 +840,7 @@
* We found an inuse dentry which was not removed from
* the LRU because of laziness during lookup. Do not free it.
*/
- if (dentry->d_lockref.count) {
+ if ((int)dentry->d_lockref.count > 0) {
spin_unlock(&dentry->d_lock);
continue;
}