diff options
| -rw-r--r-- | fs/dcache.c | 93 |
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); |