fs: seq_file - add event counter to simplify poll() support

Moving the event counter into the dynamically allocated 'struc seq_file'
allows poll() support without the need to allocate its own tracking
structure.

All current users are switched over to use the new counter.

Requested-by: Andrew Morton akpm@linux-foundation.org
Acked-by: NeilBrown <neilb@suse.de>
Tested-by: Lucas De Marchi lucas.demarchi@profusion.mobi
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 8 insertions, 21 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index ff8dc1a18cb4..1b8c33907242 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1681,19 +1681,14 @@ out:
 }
 
 #ifdef CONFIG_PROC_FS
-struct proc_swaps {
-        struct seq_file seq;
-        int event;
-};
-
 static unsigned swaps_poll(struct file *file, poll_table *wait)
 {
-        struct proc_swaps *s = file->private_data;
+        struct seq_file *seq = file->private_data;
 
         poll_wait(file, &proc_poll_wait, wait);
 
-        if (s->event != atomic_read(&proc_poll_event)) {
-                s->event = atomic_read(&proc_poll_event);
+        if (seq->poll_event != atomic_read(&proc_poll_event)) {
+                seq->poll_event = atomic_read(&proc_poll_event);
                 return POLLIN | POLLRDNORM | POLLERR | POLLPRI;
         }
 
@@ -1783,24 +1778,16 @@ static const struct seq_operations swaps_op = {
 
 static int swaps_open(struct inode *inode, struct file *file)
 {
-        struct proc_swaps *s;
+        struct seq_file *seq;
         int ret;
 
-        s = kmalloc(sizeof(struct proc_swaps), GFP_KERNEL);
-        if (!s)
-                return -ENOMEM;
-
-        file->private_data = s;
-
         ret = seq_open(file, &swaps_op);
-        if (ret) {
-                kfree(s);
+        if (ret)
                 return ret;
-        }
 
-        s->seq.private = s;
-        s->event = atomic_read(&proc_poll_event);
-        return ret;
+        seq = file->private_data;
+        seq->poll_event = atomic_read(&proc_poll_event);
+        return 0;
 }
 
 static const struct file_operations proc_swaps_operations = {