[Devel] [PATCH RHEL COMMIT] ve: Virtualize /proc/swaps to watch from inside CT

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.vz9.1.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after ark-5.14
------>
commit a330bb29df2e6753f7253b3fff51715705646607
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Tue Sep 28 19:31:11 2021 +0300

    ve: Virtualize /proc/swaps to watch from inside CT
    
    Customize /proc/swaps when showing from !ve_is_super.
    Extracted from "Initial patch".
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    (cherry picked from vz7 commit 88c087f1fdb4b0f7934804269df36035ab6b83eb)
    Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
    
    Reviewed-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    
    vz8 rebase changes:
    * virtinfo notifier substituted by direct call to si_meminfo_ve().
    
    (cherry picked from vz8 commit 72d4827a9827146d775181e5ba75c18b2c8ad163)
    Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 mm/swapfile.c | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6c3cdf079fb3..0b3493c28daa 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2792,11 +2792,36 @@ static const struct seq_operations swaps_op = {
 	.show =		swap_show
 };
 
+extern void si_meminfo_ve(struct sysinfo *si, struct ve_struct *ve);
+
+static int swap_show_ve(struct seq_file *swap, void *v)
+{
+	struct ve_struct *ve = get_exec_env();
+	struct sysinfo si;
+
+	si_meminfo_ve(&si, ve);
+
+	seq_printf(swap, "Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
+	if (!si.totalswap)
+		goto out;
+	seq_printf(swap, "%-40s%s\t%lu\t%lu\t%d\n",
+			"/dev/null",
+			"partition",
+			si.totalswap  << (PAGE_SHIFT - 10),
+			(si.totalswap - si.freeswap) << (PAGE_SHIFT - 10),
+			-1);
+out:
+	return 0;
+}
+
 static int swaps_open(struct inode *inode, struct file *file)
 {
 	struct seq_file *seq;
 	int ret;
 
+	if (!ve_is_super(get_exec_env()))
+		return single_open(file, &swap_show_ve, NULL);
+
 	ret = seq_open(file, &swaps_op);
 	if (ret)
 		return ret;
@@ -2806,12 +2831,21 @@ static int swaps_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static int swaps_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *f = file->private_data;
+
+	if (f->op != &swaps_op)
+		return single_release(inode, file);
+	return seq_release(inode, file);
+}
+
 static const struct proc_ops swaps_proc_ops = {
 	.proc_flags	= PROC_ENTRY_PERMANENT,
 	.proc_open	= swaps_open,
 	.proc_read	= seq_read,
 	.proc_lseek	= seq_lseek,
-	.proc_release	= seq_release,
+	.proc_release	= swaps_release,
 	.proc_poll	= swaps_poll,
 };