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-rw-r--r--fs/dcache.c112
1 files changed, 36 insertions, 76 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 7a5b51440af..cb25a1a5e30 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2372,7 +2372,8 @@ void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
}
EXPORT_SYMBOL(dentry_update_name_case);
-static void switch_names(struct dentry *dentry, struct dentry *target)
+static void switch_names(struct dentry *dentry, struct dentry *target,
+ bool exchange)
{
if (dname_external(target)) {
if (dname_external(dentry)) {
@@ -2406,13 +2407,19 @@ static void switch_names(struct dentry *dentry, struct dentry *target)
*/
unsigned int i;
BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
+ if (!exchange) {
+ memcpy(dentry->d_iname, target->d_name.name,
+ target->d_name.len + 1);
+ dentry->d_name.hash_len = target->d_name.hash_len;
+ return;
+ }
for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
swap(((long *) &dentry->d_iname)[i],
((long *) &target->d_iname)[i]);
}
}
}
- swap(dentry->d_name.len, target->d_name.len);
+ swap(dentry->d_name.hash_len, target->d_name.hash_len);
}
static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
@@ -2442,25 +2449,29 @@ static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
}
}
-static void dentry_unlock_parents_for_move(struct dentry *dentry,
- struct dentry *target)
+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);
}
/*
* 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.
- *
- * Note that we have to be a lot more careful about getting the hash
- * switched - we have to switch the hash value properly even if it
- * then no longer matches the actual (corrupted) string of the target.
- * The hash value has to match the hash queue that the dentry is on..
+ * 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
@@ -2506,36 +2517,30 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
d_hash(dentry->d_parent, dentry->d_name.hash));
}
- list_del(&dentry->d_u.d_child);
- list_del(&target->d_u.d_child);
-
/* Switch the names.. */
- switch_names(dentry, target);
- swap(dentry->d_name.hash, target->d_name.hash);
+ switch_names(dentry, target, exchange);
- /* ... and switch the parents */
+ /* ... and switch them in the tree */
if (IS_ROOT(dentry)) {
+ /* splicing a tree */
dentry->d_parent = target->d_parent;
target->d_parent = target;
- INIT_LIST_HEAD(&target->d_u.d_child);
+ list_del_init(&target->d_u.d_child);
+ list_move(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
} else {
+ /* swapping two dentries */
swap(dentry->d_parent, target->d_parent);
-
- /* And add them back to the (new) parent lists */
- list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
+ list_move(&target->d_u.d_child, &target->d_parent->d_subdirs);
+ list_move(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
+ if (exchange)
+ fsnotify_d_move(target);
+ fsnotify_d_move(dentry);
}
- list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
-
write_seqcount_end(&target->d_seq);
write_seqcount_end(&dentry->d_seq);
- dentry_unlock_parents_for_move(dentry, target);
- if (exchange)
- fsnotify_d_move(target);
- spin_unlock(&target->d_lock);
- fsnotify_d_move(dentry);
- spin_unlock(&dentry->d_lock);
+ dentry_unlock_for_move(dentry, target);
}
/*
@@ -2633,45 +2638,6 @@ out_err:
return ret;
}
-/*
- * Prepare an anonymous dentry for life in the superblock's dentry tree as a
- * named dentry in place of the dentry to be replaced.
- * returns with anon->d_lock held!
- */
-static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
-{
- struct dentry *dparent;
-
- dentry_lock_for_move(anon, dentry);
-
- write_seqcount_begin(&dentry->d_seq);
- write_seqcount_begin_nested(&anon->d_seq, DENTRY_D_LOCK_NESTED);
-
- dparent = dentry->d_parent;
-
- switch_names(dentry, anon);
- swap(dentry->d_name.hash, anon->d_name.hash);
-
- dentry->d_parent = dentry;
- list_del_init(&dentry->d_u.d_child);
- anon->d_parent = dparent;
- if (likely(!d_unhashed(anon))) {
- hlist_bl_lock(&anon->d_sb->s_anon);
- __hlist_bl_del(&anon->d_hash);
- anon->d_hash.pprev = NULL;
- hlist_bl_unlock(&anon->d_sb->s_anon);
- }
- list_move(&anon->d_u.d_child, &dparent->d_subdirs);
-
- write_seqcount_end(&dentry->d_seq);
- write_seqcount_end(&anon->d_seq);
-
- dentry_unlock_parents_for_move(anon, dentry);
- spin_unlock(&dentry->d_lock);
-
- /* anon->d_lock still locked, returns locked */
-}
-
/**
* d_splice_alias - splice a disconnected dentry into the tree if one exists
* @inode: the inode which may have a disconnected dentry
@@ -2717,10 +2683,8 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
return ERR_PTR(-EIO);
}
write_seqlock(&rename_lock);
- __d_materialise_dentry(dentry, new);
+ __d_move(new, dentry, false);
write_sequnlock(&rename_lock);
- _d_rehash(new);
- spin_unlock(&new->d_lock);
spin_unlock(&inode->i_lock);
security_d_instantiate(new, inode);
iput(inode);
@@ -2780,7 +2744,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
} else if (IS_ROOT(alias)) {
/* Is this an anonymous mountpoint that we
* could splice into our tree? */
- __d_materialise_dentry(dentry, alias);
+ __d_move(alias, dentry, false);
write_sequnlock(&rename_lock);
goto found;
} else {
@@ -2807,13 +2771,9 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
actual = __d_instantiate_unique(dentry, inode);
if (!actual)
actual = dentry;
- else
- BUG_ON(!d_unhashed(actual));
- spin_lock(&actual->d_lock);
+ d_rehash(actual);
found:
- _d_rehash(actual);
- spin_unlock(&actual->d_lock);
spin_unlock(&inode->i_lock);
out_nolock:
if (actual == dentry) {
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-19 04:15:04 +0000