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-rw-r--r--fs/dcache.c93
1 files changed, 30 insertions, 63 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index c870343f904f..0a58038091f2 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -67,9 +67,7 @@
* dentry->d_lock
*
* If no ancestor relationship:
- * if (dentry1 < dentry2)
- * dentry1->d_lock
- * dentry2->d_lock
+ * arbitrary, since it's serialized on rename_lock
*/
int sysctl_vfs_cache_pressure __read_mostly = 100;
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
@@ -2777,9 +2775,6 @@ static void copy_name(struct dentry *dentry, struct dentry *target)
static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
{
- /*
- * XXXX: do we really need to take target->d_lock?
- */
if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
spin_lock(&target->d_parent->d_lock);
else {
@@ -2793,40 +2788,11 @@ static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
DENTRY_D_LOCK_NESTED);
}
}
- if (target < dentry) {
- spin_lock_nested(&target->d_lock, 2);
- spin_lock_nested(&dentry->d_lock, 3);
- } else {
- spin_lock_nested(&dentry->d_lock, 2);
- spin_lock_nested(&target->d_lock, 3);
- }
-}
-
-static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target)
-{
- if (target->d_parent != dentry->d_parent)
- spin_unlock(&dentry->d_parent->d_lock);
- if (target->d_parent != target)
- spin_unlock(&target->d_parent->d_lock);
- spin_unlock(&target->d_lock);
- spin_unlock(&dentry->d_lock);
+ spin_lock_nested(&dentry->d_lock, 2);
+ spin_lock_nested(&target->d_lock, 3);
}
/*
- * When switching names, the actual string doesn't strictly have to
- * be preserved in the target - because we're dropping the target
- * anyway. As such, we can just do a simple memcpy() to copy over
- * the new name before we switch, unless we are going to rehash
- * it. Note that if we *do* unhash the target, we are not allowed
- * to rehash it without giving it a new name/hash key - whether
- * we swap or overwrite the names here, resulting name won't match
- * the reality in filesystem; it's only there for d_path() purposes.
- * Note that all of this is happening under rename_lock, so the
- * any hash lookup seeing it in the middle of manipulations will
- * be discarded anyway. So we do not care what happens to the hash
- * key in that case.
- */
-/*
* __d_move - move a dentry
* @dentry: entry to move
* @target: new dentry
@@ -2840,6 +2806,7 @@ static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target)
static void __d_move(struct dentry *dentry, struct dentry *target,
bool exchange)
{
+ struct dentry *old_parent;
struct inode *dir = NULL;
unsigned n;
if (!dentry->d_inode)
@@ -2858,49 +2825,47 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
write_seqcount_begin(&dentry->d_seq);
write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
+ old_parent = dentry->d_parent;
+
/* unhash both */
if (!d_unhashed(dentry))
___d_drop(dentry);
if (!d_unhashed(target))
___d_drop(target);
- /* Switch the names.. */
- if (exchange)
- swap_names(dentry, target);
- else
+ /* ... and switch them in the tree */
+ dentry->d_parent = target->d_parent;
+ if (!exchange) {
copy_name(dentry, target);
-
- /* rehash in new place(s) */
- __d_rehash(dentry);
- if (exchange)
- __d_rehash(target);
- else
target->d_hash.pprev = NULL;
-
- /* ... and switch them in the tree */
- if (IS_ROOT(dentry)) {
- /* splicing a tree */
- dentry->d_flags |= DCACHE_RCUACCESS;
- dentry->d_parent = target->d_parent;
- target->d_parent = target;
- list_del_init(&target->d_child);
- list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
+ dentry->d_parent->d_lockref.count++;
+ if (dentry == old_parent)
+ dentry->d_flags |= DCACHE_RCUACCESS;
+ else
+ WARN_ON(!--old_parent->d_lockref.count);
} else {
- /* swapping two dentries */
- swap(dentry->d_parent, target->d_parent);
+ target->d_parent = old_parent;
+ swap_names(dentry, target);
list_move(&target->d_child, &target->d_parent->d_subdirs);
- list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
- if (exchange)
- fsnotify_update_flags(target);
- fsnotify_update_flags(dentry);
+ __d_rehash(target);
+ fsnotify_update_flags(target);
}
+ list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
+ __d_rehash(dentry);
+ fsnotify_update_flags(dentry);
write_seqcount_end(&target->d_seq);
write_seqcount_end(&dentry->d_seq);
if (dir)
end_dir_add(dir, n);
- dentry_unlock_for_move(dentry, target);
+
+ if (dentry->d_parent != old_parent)
+ spin_unlock(&dentry->d_parent->d_lock);
+ if (dentry != old_parent)
+ spin_unlock(&old_parent->d_lock);
+ spin_unlock(&target->d_lock);
+ spin_unlock(&dentry->d_lock);
}
/*
@@ -3048,12 +3013,14 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
inode->i_sb->s_type->name,
inode->i_sb->s_id);
} else if (!IS_ROOT(new)) {
+ struct dentry *old_parent = dget(new->d_parent);
int err = __d_unalias(inode, dentry, new);
write_sequnlock(&rename_lock);
if (err) {
dput(new);
new = ERR_PTR(err);
}
+ dput(old_parent);
} else {
__d_move(new, dentry, false);
write_sequnlock(&rename_lock);