89 lines
2.5 KiB
Diff
89 lines
2.5 KiB
Diff
From 47a3a34ec251a566d97646774193e1789eb20220 Mon Sep 17 00:00:00 2001
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From: Al Viro <viro@ZenIV.linux.org.uk>
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Date: Thu, 15 Mar 2012 18:39:40 +0000
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Subject: [PATCH 022/304] vfs: fs_struct: Move code out of seqcount write
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sections
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RT cannot disable preemption in the seqcount write sections due to
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functions called which take "sleeping" spinlocks.
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Move the code out of those sections. It does not need to be there.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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fs/fs_struct.c | 27 +++++++++++++++------------
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1 file changed, 15 insertions(+), 12 deletions(-)
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diff --git a/fs/fs_struct.c b/fs/fs_struct.c
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index 78b519c..f5818c4 100644
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--- a/fs/fs_struct.c
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+++ b/fs/fs_struct.c
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@@ -26,11 +26,11 @@ void set_fs_root(struct fs_struct *fs, struct path *path)
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{
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struct path old_root;
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+ path_get_longterm(path);
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spin_lock(&fs->lock);
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write_seqcount_begin(&fs->seq);
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old_root = fs->root;
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fs->root = *path;
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- path_get_longterm(path);
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write_seqcount_end(&fs->seq);
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spin_unlock(&fs->lock);
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if (old_root.dentry)
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@@ -45,11 +45,11 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
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{
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struct path old_pwd;
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+ path_get_longterm(path);
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spin_lock(&fs->lock);
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write_seqcount_begin(&fs->seq);
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old_pwd = fs->pwd;
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fs->pwd = *path;
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- path_get_longterm(path);
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write_seqcount_end(&fs->seq);
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spin_unlock(&fs->lock);
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@@ -57,6 +57,14 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
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path_put_longterm(&old_pwd);
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}
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+static inline int replace_path(struct path *p, const struct path *old, const struct path *new)
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+{
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+ if (likely(p->dentry != old->dentry || p->mnt != old->mnt))
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+ return 0;
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+ *p = *new;
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+ return 1;
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+}
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+
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void chroot_fs_refs(struct path *old_root, struct path *new_root)
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{
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struct task_struct *g, *p;
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@@ -68,21 +76,16 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
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task_lock(p);
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fs = p->fs;
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if (fs) {
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+ int hits = 0;
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spin_lock(&fs->lock);
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write_seqcount_begin(&fs->seq);
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- if (fs->root.dentry == old_root->dentry
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- && fs->root.mnt == old_root->mnt) {
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- path_get_longterm(new_root);
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- fs->root = *new_root;
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+ hits += replace_path(&fs->root, old_root, new_root);
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+ hits += replace_path(&fs->pwd, old_root, new_root);
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+ write_seqcount_end(&fs->seq);
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+ while (hits--) {
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count++;
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- }
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- if (fs->pwd.dentry == old_root->dentry
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- && fs->pwd.mnt == old_root->mnt) {
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path_get_longterm(new_root);
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- fs->pwd = *new_root;
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- count++;
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}
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- write_seqcount_end(&fs->seq);
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spin_unlock(&fs->lock);
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}
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task_unlock(p);
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