From a5969cabbb4660eab42b6ef0412cbbd1200cf14d Mon Sep 17 00:00:00 2001 From: hc <hc@nodka.com> Date: Sat, 12 Oct 2024 07:10:09 +0000 Subject: [PATCH] 修改led为gpio --- kernel/Documentation/filesystems/directory-locking.rst | 26 ++++++++++++++------------ 1 files changed, 14 insertions(+), 12 deletions(-) diff --git a/kernel/Documentation/filesystems/directory-locking.rst b/kernel/Documentation/filesystems/directory-locking.rst index 504ba94..dccd61c 100644 --- a/kernel/Documentation/filesystems/directory-locking.rst +++ b/kernel/Documentation/filesystems/directory-locking.rst @@ -22,12 +22,11 @@ 3) object removal. Locking rules: caller locks parent, finds victim, locks victim and calls the method. Locks are exclusive. -4) rename() that is _not_ cross-directory. Locking rules: caller locks -the parent and finds source and target. In case of exchange (with -RENAME_EXCHANGE in flags argument) lock both. In any case, -if the target already exists, lock it. If the source is a non-directory, -lock it. If we need to lock both, lock them in inode pointer order. -Then call the method. All locks are exclusive. +4) rename() that is _not_ cross-directory. Locking rules: caller locks the +parent and finds source and target. We lock both (provided they exist). If we +need to lock two inodes of different type (dir vs non-dir), we lock directory +first. If we need to lock two inodes of the same type, lock them in inode +pointer order. Then call the method. All locks are exclusive. NB: we might get away with locking the source (and target in exchange case) shared. @@ -44,15 +43,17 @@ rules: * lock the filesystem - * lock parents in "ancestors first" order. + * lock parents in "ancestors first" order. If one is not ancestor of + the other, lock them in inode pointer order. * find source and target. * if old parent is equal to or is a descendent of target fail with -ENOTEMPTY * if new parent is equal to or is a descendent of source fail with -ELOOP - * If it's an exchange, lock both the source and the target. - * If the target exists, lock it. If the source is a non-directory, - lock it. If we need to lock both, do so in inode pointer order. + * Lock both the source and the target provided they exist. If we + need to lock two inodes of different type (dir vs non-dir), we lock + the directory first. If we need to lock two inodes of the same type, + lock them in inode pointer order. * call the method. All ->i_rwsem are taken exclusive. Again, we might get away with locking @@ -66,8 +67,9 @@ Proof: - First of all, at any moment we have a partial ordering of the - objects - A < B iff A is an ancestor of B. + First of all, at any moment we have a linear ordering of the + objects - A < B iff (A is an ancestor of B) or (B is not an ancestor + of A and ptr(A) < ptr(B)). That ordering can change. However, the following is true: -- Gitblit v1.6.2