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Date: Mon, 24 Feb 2020 10:27:49 -0600
From: ebiederm@...ssion.com (Eric W. Biederman)
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Al Viro <viro@...iv.linux.org.uk>, LKML <linux-kernel@...r.kernel.org>, Kernel Hardening <kernel-hardening@...ts.openwall.com>, Linux API <linux-api@...r.kernel.org>, Linux FS Devel <linux-fsdevel@...r.kernel.org>, Linux Security Module <linux-security-module@...r.kernel.org>, Akinobu Mita <akinobu.mita@...il.com>, Alexey Dobriyan <adobriyan@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Andy Lutomirski <luto@...nel.org>, Daniel Micay <danielmicay@...il.com>, Djalal Harouni <tixxdz@...il.com>, "Dmitry V . Levin" <ldv@...linux.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Ingo Molnar <mingo@...nel.org>, "J . Bruce Fields" <bfields@...ldses.org>, Jeff Layton <jlayton@...chiereds.net>, Jonathan Corbet <corbet@....net>, Kees Cook <keescook@...omium.org>, Oleg Nesterov <oleg@...hat.com>, Solar Designer <solar@...nwall.com>, Alexey Gladkov <gladkov.alexey@...il.com>
Subject: [PATCH v2 3/6] proc: In proc_prune_siblings_dcache cache an aquired super block
Because there are likely to be several sysctls in a row on the
same superblock cache the super_block after the count has
been raised and don't deactivate it until we are processing
another super_block.
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
fs/proc/inode.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 74ce4a8d05eb..fa2dc732cd77 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -108,10 +108,11 @@ void proc_prune_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
struct inode *inode;
struct proc_inode *ei;
struct hlist_node *node;
- struct super_block *sb;
+ struct super_block *old_sb = NULL;
rcu_read_lock();
for (;;) {
+ struct super_block *sb;
node = hlist_first_rcu(inodes);
if (!node)
break;
@@ -122,23 +123,28 @@ void proc_prune_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
inode = &ei->vfs_inode;
sb = inode->i_sb;
- if (!atomic_inc_not_zero(&sb->s_active))
+ if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
continue;
inode = igrab(inode);
rcu_read_unlock();
+ if (sb != old_sb) {
+ if (old_sb)
+ deactivate_super(old_sb);
+ old_sb = sb;
+ }
if (unlikely(!inode)) {
- deactivate_super(sb);
rcu_read_lock();
continue;
}
d_prune_aliases(inode);
iput(inode);
- deactivate_super(sb);
rcu_read_lock();
}
rcu_read_unlock();
+ if (old_sb)
+ deactivate_super(old_sb);
}
static int proc_show_options(struct seq_file *seq, struct dentry *root)
--
2.25.0
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