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, 18 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 91e31e260b4a..dfc9425db70b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6394,16 +6394,11 @@ static void md_seq_stop(struct seq_file *seq, void *v)
                 mddev_put(mddev);
 }
 
-struct mdstat_info {
-        int event;
-};
-
 static int md_seq_show(struct seq_file *seq, void *v)
 {
         mddev_t *mddev = v;
         sector_t sectors;
         mdk_rdev_t *rdev;
-        struct mdstat_info *mi = seq->private;
         struct bitmap *bitmap;
 
         if (v == (void*)1) {
@@ -6415,7 +6410,7 @@ static int md_seq_show(struct seq_file *seq, void *v)
 
                 spin_unlock(&pers_lock);
                 seq_printf(seq, "\n");
-                mi->event = atomic_read(&md_event_count);
+                seq->poll_event = atomic_read(&md_event_count);
                 return 0;
         }
         if (v == (void*)2) {
@@ -6527,26 +6522,21 @@ static const struct seq_operations md_seq_ops = {
 
 static int md_seq_open(struct inode *inode, struct file *file)
 {
+        struct seq_file *seq;
         int error;
-        struct mdstat_info *mi = kmalloc(sizeof(*mi), GFP_KERNEL);
-        if (mi == NULL)
-                return -ENOMEM;
 
         error = seq_open(file, &md_seq_ops);
         if (error)
-                kfree(mi);
-        else {
-                struct seq_file *p = file->private_data;
-                p->private = mi;
-                mi->event = atomic_read(&md_event_count);
-        }
+                return error;
+
+        seq = file->private_data;
+        seq->poll_event = atomic_read(&md_event_count);
         return error;
 }
 
 static unsigned int mdstat_poll(struct file *filp, poll_table *wait)
 {
-        struct seq_file *m = filp->private_data;
-        struct mdstat_info *mi = m->private;
+        struct seq_file *seq = filp->private_data;
         int mask;
 
         poll_wait(filp, &md_event_waiters, wait);
@@ -6554,7 +6544,7 @@ static unsigned int mdstat_poll(struct file *filp, poll_table *wait)
         /* always allow read */
         mask = POLLIN | POLLRDNORM;
 
-        if (mi->event != atomic_read(&md_event_count))
+        if (seq->poll_event != atomic_read(&md_event_count))
                 mask |= POLLERR | POLLPRI;
         return mask;
 }